Environmental Science and Engineering Subseries: Environmental Science Series Editors: R. Allan · U. Förstner · W. Salomons
Lambert A. Rivard With contributions by Q. Hugh J. Gwyn
Geohazardassociated Geounits Atlas and Glossary
With 995 Images and CD-ROM
Author Lambert A. Rivard 201-300 St-Georges St-Lambert QC J4P 3P9 CANADA
[email protected] Contributor Q. Hugh J. Gwyn, Ph.D 445, rue Woodward North Hatley QC J0B 2C0 CANADA
[email protected] ISBN 978-3-540-20296-7
e-ISBN 978-3-540-68885-3
Environmental Science and Engineering ISSN: 1863-5520 Library of Congress Control Number: 2008936682 © 2009 Springer-Verlag Berlin Heidelberg This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitations, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer. Violations are liable to prosecution under the German Copyright Law. The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Cover design: deblik, Berlin Typesetting: Stasch · Bayreuth Production: Agata Oelschläger, Heidelberg Printed on acid-free paper 9 8 7 6 5 4 3 2 1 springer.com
30/2132/AO
To Carla Hehner-Rivard on whom great personal stress was imposed in this endeavour. Her selfless devotion, her arduous coordinating effort in dealing with the often re-ordered digital data base of the atlas’ illustrations and text, her protracted correspondence in obtaining permissions for close to 1 000 illustrations, and her endless patience with her husband’s importunities, contributed immeasurably to the book’s realization.
Preface
The media now broadcast loss of life and property damage caused by a variety of geologic hazards and geologic terrains worldwide on a near-daily frequency and in near-real-time.
Themes This Atlas and Glossary is the result of the author’s lifetime vocation, practice and research worldwide on the application of vertical air photography and Earth Observation satellite images to geomorphology. His teaching experience and consulting for civil engineers led him to increasingly emphasize the links between specific geounits and their inherent geologic hazards. The idea of producing an atlas documenting these links was inspired by the activities of the International Decade for Natural Disaster Reduction, and he began work on the book in 1998. The integrity of any structure has to rely on the ground on which it stands. There is a general awareness that such common hazards as rock falls, rock slides, and floods are associated with certain geologic formations, structures, and topographic situations. However, this knowledge is not as widespread as a dozen other destructive hazards that threaten human life and property, and are functionally associated with particular geologic processes and formations. These relationships have been established by distilling a selection of geounits as agents of, or susceptible to, specific geohazards, from a comprehensive photogeologic classification and photographic archive that was developed during the author’s training and consultancy work.
Objectives The Atlas and Glossary is a portfolio approach that aims to provide an accessible source of concise information for earth science professionals and students who need to understand the hazards that are associated with specific geological units and geostructures that are mappable using airphotos and satellite images. All the material is presented as integrated data sets whose texts and figures of world wide coverage characterizing a geounit and its geohazards, are a convenient synthesis of information providing a rapid insight for the user from frequently widely scattered sources.
The Illustrations The Atlas and Glossary includes 995 satellite images, vertical airphotos, air perspective views, ground photos and line-art figures that depict and document the classified geounits in their varied photogeologic appearances in diverse biophysical environments on a planet that is too easily thought of as small. Eighty-nine countries are represented.
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Preface
Characterization of Geounits The descriptions of geounit data sets are concise syntheses of current geoscience knowledge. A geounit, as an agent of a geohazard or its susceptibility to other geohazards is discussed in relation to a set of fifteen hazard types detectable on air photos and images under the heading geohazard relations.
Photogeologic Interpretation The Classification provides a set of descriptor codes for the identification of photogeologic units. Interpretations delineate and annotate geounits on the majority of the satellite images and airphotos.
Stereo Viewing The Presentation section of the Introduction explains the inclusion of a CD-ROM to provide stereo viewing of airphoto figures in the Atlas.
Copyright Every effort was made to obtain permission to reproduce copyright material throughout this book. The illustrations are all drawn from an archive of over 400 files. Because some date back more than four decades, the provenance of some has been lost and their source is listed as unattributed. If any proper acknowledgment has not been made, this oversight will be corrected in subsequent editions of the Atlas and Glossary.
Acknowledgments
Preparation of a book, especially a first edition, needs the help and expertise of many people. First among those to whom we are most greatly indebted is Nicholas W. E. Lee. This civil engineer and life-long friend who long presided a photographic survey company, actively promoted the application airphoto interpretation to site selection in civil engineering projects. Nicholas strongly encouraged and supported the author at critical moments in his career. He saw to it that his early experience was developed within international projects. We are particularly grateful to the staff of the Earth Science Information Centre of Natural Resources Canada in Ottawa, especially Penny Minter and Irène Kumar of the Map Library, for their unstinting and prompt response to endless requests. The National Air Photo Library generously permitted the reproduction of numerous stereo and other airphotos, and its staff constantly responded to urgent requests for information. Dr. Stéphane Péloquin, consultant in remote sensing for mineral exploration and a specialist in the development of computer programs for applied earth science made contributions in the methodical formulations that were used for some of the processing of digital data. The initial scanning and processing of the mass of illustrations was performed by Sophie Gaudreau, Micheline Léger and Carl Garneau under the supervision of Martin Trépanier who organized this phase of the book production at Groupe BGJLR Inc. in Québec City. At Springer-Verlag, Dr. Christian Witschel, Executive-Editor Geosciences recognized the merit of our concept of an airphoto and satelite image based atlas relating specific geounits to specific geohazards and made the commitment to see it published. Agata Oelschläger efficiently and with indulgence coordinated the production process. Armin Stasch of Stasch Verlagsservice reconciled our layout and presentation ideals with publishing realities. Lastly, the true source of this atlas are the students of Civil Engineering Courses 303 and 439 in the Civil Engineering Department, McGill University. Their successive classes over the years constituted a persistent challenge to the author to continually refine the content of the sets of pedagogic data, collected, organized and re-organized, for a more effective characterization and presentation of the environmentally varied appearance of given photogeologic units. These cumulative data sets became the basis of the Atlas.
Author and Contributors
Mr. Rivard takes responsibility for the full content of the book, any mistakes, omissions or errors are his. He performed the photogeological interpretations and wrote the comments of the figures of the Part IV atlas. Dr. Q. Hugh J. Gwyn did the initial copy-editing and vetting of the texts of Part I, Part II, Part III and the 160 geounit characterizations of the Glossary sections of the data sets of Part IV. His continued support and technical expertise contributed greatly to the final publication. Major contributions were made by Carla Hehner-Rivard in the overall production control and coordination, figure/text matching and editing, adaptation of line art, image enhancement and picture quality control.
Contents
Part I Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Definition of a Geohazard . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Geohazard Types . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Definition of a Geounit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Selection of Geounits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 Airphotos and Satellite Images as Sources of Geohazard Information . . . . . . . . . . . . . . . . 2 Presentation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 Part II User’s Guide to the Atlas and Glossary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 II-1 Classification Basis of the Photogeologic Geounits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 II-2 Selection Criteria of the Geounits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 II-3 Characterization of the Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 II-3.1 Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 II-3.2 Mappability of Photogeologic Geounits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 II-3.3 Relationship to Other Image-Based Geo-Science Terrain Classifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 II-3.4 Present Professional Context of the Classification . . . . . . . . . . . . . . . . . . . . . . . . 6 II-4 Organization of the Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 II-4.1 Division 1: Magmatic Rocks and Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 II-4.2 Division 2: Sedimentary Rocks and Duricrusts . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 II-4.3 Division 3: Geostructures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 II-4.4 Division 4: Surficial Deposits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 II-5 Geounit Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 II-5.1 Geostructure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 II-5.2 Geounit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 II-5.3 Variant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 II-5.4 Component . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 II-5.5 Relative Chronology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 II-6 Mode of Designation of Mapped Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 General Bibliography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Select Bibliography of Remote Sensing Technology for Geologic Interpretation . . . . . . . . . 9
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Part III Classification of Geohazard-Related Geounits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Division 1 Division 2 Division 3 Division 4 Division 4 Division 4 Division 4 Division 4 Division 4 Division 4
Magmatic Rocks and Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Sedimentary Rocks and Duricrusts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Geostructures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Surficial Deposits · Group – Aeolian Deposits . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Surficial Deposits · Group – Basinal Sediments . . . . . . . . . . . . . . . . . . . . . . . . . 17 Surficial Deposits · Group – Fluvial System Sediments . . . . . . . . . . . . . . . . 18 Surficial Deposits · Group – Marine Littoral Systems . . . . . . . . . . . . . . . . . . 19 Surficial Deposits · Group – Paraglacial Geosystems . . . . . . . . . . . . . . . . . . 20 Surficial Deposits · Group – Periglacial-Related Forms . . . . . . . . . . . . . . . 20 Surficial Deposits · Group – Mass Movement Materials . . . . . . . . . . . . . . . 21
Part IV Data Sets of the Atlas and Glossary of the Geounits and Variants . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 Division 1 Magmatic Rocks and Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Group X Extrusive Magmas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 X1 Basaltic Flows, Flow Fields, or Plateaus (Trapps) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26 X1.1 Local Slope Flows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33 X1.2 Local Valley Flows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38 X1.3 Disturbed-Dissected Basalts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43 X1.4 Dissected Alkaline Basalts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 X2 Interbedded Lavas and Pyroclastics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55 X2.1 Interbedded Lavas and Pyroclastics, Disturbed Facies . . . . . . . . . . . . . . . . . 58 X2.2 Interbedded Lavas and Pyroclastics, Dissected Facies . . . . . . . . . . . . . . . . . . 60 Group P Tephra Deposits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 Sub-group Pf · Falls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 Pf1 Pyroclastic Falls . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 Pf1.1 Ash-Tuff Hills . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72 Pf1.3 Ash-Tuff Plains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76 Sub-group Ps · Pyroclastic Density Current Deposits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 Ps1 Pyroclastic Flows and Surges, Undifferentiated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80 Ps1.1 Macroscopic Ignimbrite Outflow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86 Group V Cenozoic Volcanic Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 Sub-group Vs · Viscous Lava Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 Vs1 Autonomous Domes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 94 Vs1.1 Domes in Cones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99 Vs1.2 Flow-Dome Complexes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 Vs2 Coulées . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 112 Sub-group Vc · Major Conical Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 Vc1 Stratovolcanoes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 Vc1.1 Dissected Cones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128
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Vc2 Shield Volcanoes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vc3 Calderas and Tectonic Depressions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vc3.1 Calderas on Stratovolcanoes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vc3.2 Calderas with Post-Caldera Cones and Domes . . . . . . . . . . . . . . . . . . . . . . . . . Vc3.3 Large Silicic Calderas with Resurgent Domes . . . . . . . . . . . . . . . . . . . . . . . . . . Vc3.4 Calderas on Shield Volcanoes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Vc4 Volcanic Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
141 146 146 156 166 170 174
Group A Modern Volcanic-Epliclastic Deposits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A1 Lahars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A2 Volcanic Debris Avalanches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . A3 Hydrocinerite Plain Deposits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
183 183 188 196
Division 2 Sedimentary Rocks and Duricrusts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 203 Group K Carbonates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 204 K3 Karst Plains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 205 Sub-group Kp · Holokarst Residual Terrains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Kp1 Karst Plateaus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Kp1.1 Corridored Plateaus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Kp2 Pyramid-Labyrinth Karst Terrains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
211 211 222 228
Sub-group Kn · Holokarst Erosional Terrains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 Kn1 Poljes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 237 Kn2 Fluviokarst Terrains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 242 Sub-group Kc · Amorphous Carbonates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246 Kc2 Chalk and Marl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 246 Kc4 Interbedded Carbonates . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 257 Group H Saline and Phosphatic Rocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262 H1 Cemented Evaporites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262 Group S Detrital Rocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S1.2 Weak Rudites-Arenites, Upland Facies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S1.5 Weak Rudites-Arenites, Lowland Facies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S2 Siltstones and Lutites . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . S2.1 Siltstones and Lutites, Dissected Facies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
266 266 276 284 290
Group W Interbedded Sequences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . W1 Interbedded Sedimentary Rocks, Undivided . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . W1.1 Coal Seams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . W4 Interbedded Weak Rock Sequences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
302 302 310 315
Group D Duricrusts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327 D1 Ferricretes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 327
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Division 3 Geostructures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333 Group Gravity Structures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Stock Salt-Evaporite Diapirs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.1 Pillow Domes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.2 Duplex Stocks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.3 Extrusive Salt Diapirs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11.4 Elongate Diapirs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
334 334 340 346 348 351
Group Fault Line Traces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 Dip-Slip Normal Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12.1 Multidirectional Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13 Strike-slip Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 Thrust Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 Composite Lineaments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 Horst Dip-Slip Fault Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Graben Dip-Slip Faults . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.1 Graben Conjugate Fault Pairs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17.2 Single Fault Asymmetric Grabens . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
357 357 367 370 378 387 390 398 398 407
Group General Lineaments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 Mesoscale Fracture Traces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 Macroscale Discontinuities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.1 Geomorphologic Discontinuities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19.2 Radiometric Discontinuities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 Synergic Lineaments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
410 410 419 419 427 431
Division 4 Surficial Deposits · Group E – Aeolian Deposits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 433 Sub-group Et · Inland Aeolian Deposits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 434 Et1.1 Blanket Loess . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 434 Sub-group Ef · Duneless Deposits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 440 Ef1 Sand Sheets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 440 Ef2 Sand Streaks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 447 Sub-group Ed · Sand Dunes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ed1 Free Inland Dunes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ed1.1 Linear Dunes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ed1.2 Transverse Dunes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ed1.3 Barchanoid Ridges . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ed1.4 Barkhan Dunes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ed1.5 Star Dunes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ed1.6 Dome Dunes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ed1.7 Parabolic Dunes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ed1.8 Dune Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ed2 Dune Complexes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
452 452 453 462 465 471 475 479 481 485 486
Contents
Sub-group Eo · Obstacle Dunes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Eo1 Shadow Dunes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Eo3 Climbing Dunes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Eo4 Falling Dunes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
491 491 496 500
Sub-group Ec · Coastal Beach Backshore Dunes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ec1 Parallel Dunes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ec2 Transgressive Dunes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ec3 Free Dunes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
504 504 509 518
Division 4 Surficial Deposits · Group L – Basinal Sediments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 525 L1 L2 L3
Pleistocene Glaciolacustrine Sediments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 526 Holocene Playa Basins and Pleistocene Pluvial Lacustrine Sediments . . . . . . 540 Quaternary Drained Lakebeds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 549
Division 4 Surficial Deposits · Group F – Fluvial System Sediments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 555 Sub-group Fu · Upland Margin Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 556 Fu1 Alluvial Fans . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 556 Fu1/Mv1.2 Alluvial Fan and Talus Cone Complexes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 572 Sub-group Fv · Valley Fill Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fv1 Braided Alluvial Deposits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fv1.1 High Gradient Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fv1.2 Low Gradient Setting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fv2 Meandering Alluvial Deposits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
580 581 582 587 599
Sub-group Fv · Valley Fill Composite Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 637 Fv1.1/Fv2 Meandering-Braided Complexes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 637 Sub-group Fw · Holocene Deltas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fw1 Arcuate Deltas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fw2 Elongate Deltas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fw3 Estuarine Deltas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fw3.1 Macrotidal Estuaries . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fw4 Cuspate Deltas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
644 645 651 657 661 668
Sub-group Fr · Climatic Deltas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 675 Fr2 Inland Deltas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 675 Division 4 Surficial Deposits · Group B – Marine Littoral Systems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 681 Sub-group Br · Bedrock Littorals . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Br2.1 High Rock Cliffs Unstable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Br3.1 Low Rock Cliffs Weak . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Br4.1 Bedrock Hills Weak . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Br6 Tectonic Eustatic Marine Terraces . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Br7 Bedrock Plains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
682 683 686 689 691 695
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XVIII Contents
Sub-group Bb · Residual Shorelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 698 Bb1 Bluffs in Unconsolidated Sediments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 698 Bb1.1 Bluffs in Frozen Sediments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 704 Sub-group Bw · Wave and Current-formed Littoral Sediments . . . . . . . . . . . . . . . . . . Bw2 Offshore Bars . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bw3 Near-Shore Barrier Beaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bw3.1 Bay Barrier Beaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bw4 Attached Beaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bw5 Spits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bw6 Tombolos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
709 709 712 720 729 732 736
Sub-group Bl · Sea Ice and Sea Ice Related Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 741 Bl1 Sea Ice Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 741 Sub-group Bt · Tidal Regime Deposits and Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 745 Bt1 Lagoons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 745 Sub-group Bc · Coastal Plains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bc1 Plains of Marine Sediments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bc2 Passive Margin Sediments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bc3 Glaciomarine Plains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bc4 Fluviomarine Plains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
778 778 792 795 806
Sub-group Bp · Low Latitude Offshore Carbonate Platforms . . . . . . . . . . . . . . . . . . . . 815 Bp1 Subtidal Banks . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 815 Division 4 Surficial Deposits · Group G – Paraglacial Geosystems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 819 Sub-group Gl · Ice Bodies . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 820 Gl4 Outlet Tidewater Glaciers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 820 Gl5 Valley Glaciers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 830 Sub-group Gf · Glaciofluvial Deposits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 845 Gf4 Eroded Till Plains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 845 Gf5 Boulder Fields . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 851 Division 4 Surficial Deposits · Group Z – Periglacial-Related Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 855 Sub-group Zi · Ground Ice Units . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 857 Zi4 Ice Wedge Polygons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 857 Sub-group Zm · Cryoturbated Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Zm1 Gelifluction Slopes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Zm1.1 Gelifluction Sheets and Lobes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Zm1.2 Gelifluction Stripes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Zm2 Rock Glaciers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Zm5 Detachment Failures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
869 869 869 879 885 893
Sub-group Zk · Thermokarst Terrain . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 895 Zk1 Subsidence Terrains . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 895 Zk2 Retrogressive Thaw-Flow Slides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 904
Contents
Division 4 Surficial Deposits · Group M – Mass Movement Materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 907 Sub-group Mv · Falls and Subsidences . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mv1 Talus-Rockfalls Undifferentiated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mv1.1 Talus Sheets . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mv1.2 Talus Cones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mv2 Rock Avalanches (Sturzströmen) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mv2.1 Rock Avalanches, Inactive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mv3 Toppled Rock Slabs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mv4 Subsidences, Sudden . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mv5 Subsidence Zones, Gradual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
908 908 912 922 926 930 936 938 944
Sub-group Ml · Lateral Spreads . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 953 Ml1 Rock Block Glides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 953 Sub-group Mc · Diagonal Creeps . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 956 Mc1 Colluvial Mantle Movement Zones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 956 Sub-group Ms · Slides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ms1 Planar Rock Slides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ms1.1 Planar Rock Slides, Inactive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ms2 Debris Slides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ms2.1 Debris Avalanches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ms3 Rotational Rock Slumps, Undifferentiated . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ms3.1 Rotational Rock Slumps, Inactive . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ms4 Snow Avalanches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ms5 Ice Avalanches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
959 959 964 969 972 977 984 986 992
Sub-group Mf · Flows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 998 Mf1 Retrogressive Flows in Unconsolidated Sediments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 998 Mf1.1 Retrogressive Slides in Unconsolidated Sediments and Detrital Rocks Substrate . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1007 Mf2 Earth Flows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1010 Mf2.1 Slow Earth Flows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1017 Mf3 Debris-Mud Flows . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1021 Mf4 Mountain Valley Natural Dams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1036 Mf4.1 Landslide Dams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1036 Mf4.2 Moraine Dams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1043 Mf4.3 Glacier Dams . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1048 Appendix Abbreviations and Acronyms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1053
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I Part I Introduction
This book is an Atlas and Glossary of data sets of geounits associated with geohazards that are detectable in optical and radar airphotos and satellite images. These sets are intended to provide a reference and instructional aid for geoscience professionals and students in physical, engineering, environmental geology as well as hydrogeology, geomorphology and physical geography. Its geographical reach is global. Hazard mitigation measures are illustrated incidentally where they happen to be evident in the airphotos and space images or within characterizing photos of geounits.
Background The approach to environmental studies used in the Atlas and Glossary is a result of the author’s more than three decades of consultancy practice worldwide, and teaching of photogeology and remote sensing in engineering geology and physical geography. During that time a scheme was evolved to order and classify geological units as they are resolved spatially and spectrally on airphotos and images. This has resulted in a comprehensive updated glossary of photogeological units comprising 177 basic units and 178 variants. The present Atlas Glossary was derived from the more general glossary by applying the method described below to identify geohazard-associated geounits. It comprises autonomous data sets of 94 basic units and 70 facies.
Definition of a Geohazard The following definition of a geohazard is extracted from that as given by Gares et al. (1994, p 5): “Geomorphic hazards must be regarded as the suite of threats to human resources arising from instability of the surface features of the earth. The threat arises from landform response to surficial processes, although the initiating processes may originate at great distances from the surface.”
Geohazard Types The geounits have been evaluated as associated with 15 principal hazard types. They are either agents of a particular hazard or are susceptible to particular hazards including three hydrologic hazards. The hazard types are listed in Table I.1. This dual evaluation of a geounit incorporates both hazard process and landform response as proposed by Gare et al. (1994).
L.A. Rivard, Geohazard-associated Geounits, Environmental Science and Engineering, DOI 10.1007/b93844_1, © Springer-Verlag Berlin Heidelberg 2009
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Airphotos and Satellite Images as Sources of Geohazard Information
A well-illustrated general overview of geological processes and related geohazards is presented in United States Geological Survey Bull. 2149, Geologic Processes at the Land Surface (1996).
Definition of a Geounit A Geounit is a portion of a tract of land having recognizable lithologic contact boundaries at scales related to airphotos and space imagery, and whose overall homogeneity is a function of its genesis, composition, geologic structure and relief type.
Selection of Geounits The methodology to produce the list of geounits associated with geohazards consisted of a sequence of empirical selective questions and decisions. Considering the intrinsic geologic characteristics of a given unit and its typical topographic situation relative to surrounding geounits is the unit judged to be stable or unstable with respect to the listed geohazard types For which of the geohazard types is the unstable unit intrinsically a potential agent? (e.g. flow/liquefaction hazard is intrinsic to a glaciomarine plain; solution hazard is intrinsic to the karst plateau) To which of the hazard types extrinsic to the geounit is it potentially susceptible? (e.g. a glaciomarine plain is potentially susceptible to the flooding hazard; the karst plateau is susceptible to the fall and subsidence hazards) A useful two-page spread overview of ground geohazard associations is presented in T. Waltham, Foundations of Engineering Geology, Spon Press, 2002; Topic 37 – Understanding Ground Conditions.
Detection and identification of geounits and their associated geohazards is a geomorphological science method based on spatial and spectral attributes of landforms visible on stereoscopic airphotos or high resolution stereoscopic Earth Observation satellite images. The attributes (relief, shape, size, reflectance, locational context) are based on concepts and principles which were developed by photogeologists eighty years ago. Monoscopic satellite images are generally less suitable for detailed mapping of geohazard types presented in this atlas. Brown et al. 2007 reported predictive mapping of surficial materials in the arctic using Landsat TM and digital elevation data. The maps produced in advance of field work were found to be approximately 50% accurate. The literature on hazard types per se is voluminous while that on the use of aerospace data as sources of geohazard information is uneven. A concise overview of the former, where use of airphotos is mentioned frequently, is the monograph by Legget and Karrow (1983) on geology and civil engineering. Referring to such problems, and leaving costs aside, Waltham states “Civil engineering design can accommodate almost any ground conditions which are correctly assessed and understood.” (Spon Press 2002). A guide to special problems limited to slope instabilities of hazard types 3 to 8, is given by Soeters and van Westen (1996). The detection and interpretability of hazard types 3 to 8 in that report is summarized as follows: “Experience at the International Institute for Aerospace Survey and Earth Sciences with the use of photointerpretation techniques in support of landslide hazard investigations in various climatic zones and for a considerable variety of terrain conditions suggests that a scale of 1 : 15 000 appears to be the optimum scale for aerial photographs, whereas a scale of 1 : 25 000 should be considered the smallest useful scale for analysing slope instability phenomena with aerial photographs. A slope failure may be recognized on smaller scale photography provided that the failure is large enough and the photographic contrast is sufficient.” (Soeters and van Westen 1996, p 159). Discussions of aerospace data applications to hazard types 9 to 12 are scattered in the geological and civil engineering literature pertaining to the description of geounits related to those hazards. Hydrologic hazards 13, 14, and 15 are particularly amenable to monitoring and mapping by satellite optical and cloud penetrating microwave sensors. Published information on the subject is abundant and readily available (search keywords “floodplains”, “barrier beaches”, “lagoons”, “coastal plains”).
Presentation
Much of current R&D on geologic remote sensing systems focuses on spectral attributes of lithologies. Recent systems of note are ASTER (Advanced Spaceborne Thermal Emission and Reflection Radiometer) which captures data in 14 spectral bands in 15, 30 and 90 m pixels and in 60 × 60 km scenes. The Shuttle Radar Topography Mission (STRM) used radar interferometry to derive elevation models for 80% of the Earth’s landmass (±60 degrees latitude) with 30 and 90 m pixels depending on locations and 20 m vertical accuracy. Table I.2 illustrates the usefulness and the principal characteristics of satellite images for the purpose of geohazard study. The currently Internet accessible Global Earth EO satellite imaging system is a highly useful coverage complementary to the scenes and airphotos that make up this Atlas. The coordinates of some Figures differ from those of that system.
Presentation The 160 Geounits and Variants are ordered as data sets of each unit which include a Glossary of descriptive text and figures, an Atlas of interpreted satellite images and vertical airphotos and a select bibliography.
The Glossary portion includes a concise monograph that characterizes the unit, states its geohazard relations and provides a select bibliography of key texts and primary papers. The text is supported by various graphics – cross sections, block diagrams, maps – ground and air perspective photos. A total of 477 of such characterizing figures are presented. Some reproductions, though of less than top quality, are included because they were considered vital for proper documentation of a particular geounit. The Atlas portion consists of a set of geographically and geologically located vertical airphotos and/or satellite images each of which is accompanied by interpretative comments and the majority of which are overlaid with unit delineations and/or annotations. A total of 518 figures make up the Atlas including 142 EO satellite images, 20 satellite radar images, 54 monoscopic vertical airphotos, 90 mounted stereograms and 212 CD-ROM based free and mounted stereo airphoto pairs and triplets. The scales given are those of the figures as published by the source and, in individual cases, may not be exactly as reproduced in the Atlas.
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The CD-ROM contains the air photos that complete those in the body of the book for stereo viewing as indicated by Soeters and van Westen, p 158. “Landforms are among the most conspicuous phenomena appearing in the imagery obtained from aerospace. This is particularly the case if a three-dimensional image suitable for stereoscopic study is involved and provides a basis for deductive interpretation on the basis of morphogenetical reasoning”. (Verstappen 1977). Such stereo viewing of terrain is so valuable for the detection and interpretation of geounits that stereo capability has been incorporated into the more recent EO satellites. Both stereopairs and stereotriplets are included in the CD-ROM, from which paper copies of the airphotos can be printed to match those in the book. Stereo viewing is accomplished by laying a print beside its mate photo in the book and viewing them with the use of a simple pocket stereoscope. A useful comparison may be made of the CD-ROM sets with their monoscopic Google Earth image on the Internet. Bibliographies. The following text paraphrases that of Ernst Breisach in On the Future of History (Chicago 2003). In the age of extensive electronic databases and access to online catalogues of numerous libraries, the
ideal of comprehensiveness can yield its place to other objectives in the compilation of bibliographies. The select bibliographies of each geounit and variant support the purpose of this glossary; to be a guide to the characterization of geounits. Besides documenting the resources used by the author, the selected works will facilitate the reader’s own interests and explorations.
References Brown O, Harris JR, Utting D, Little EC (2007) Remote predictive mapping on surficial materials on nothern Baffin Island: Developing and testing techniques using Landsat TM and digital elevation data. GSC, Current Research 2007-B1, p 12 Gares PA, Sherman J, Nordstrom KF (1994) Geomorphology and natural hazards. Geomorphology 10 Hutchinson JN (2001) Reading the ground: Morphology and geology in site appraisal. Quarterly Journal of Engineering Geology and Hydrogeology 34:7–50 Legget RF, Karrow PF (1983) Handbook of geology in civil engineering. McGraw-Hill, New York Soeters R, van Westen CJ (1996) Slope instability recognition, analysis, and zonation. In: Turner AK, Schuster RL (eds) Landslides: Investigation and mitigation. Special Report 247. Transportation Research Board, National Research Council, Washington, D.C., p 158–159 Verstappen HTh (1977) Remote sensing in geomorphology. Elsevier Scientific Publishing Co., NY Waltham T (2002) Foundations of engineering geology, 2nd edn. Spon Press, London, pp 74–75
II Part II User’s Guide to the Atlas and Glossary
II-1 Classification Basis of the Photogeologic Geounits The logic underlying the classification of the geounits is essentially the same as that which supports other forms of geologic mapping. Varnes (1974) has stated “Four fundamental categories of attributes apply to (geologic) maps; these pertain to time, space, the inherent qualities or properties of real matter, and the relations of objects. Geologic units commonly are defined by combinations of these four kinds of attributes.” The typological individuals of the classification conform to these attributes and their nomenclature conforms to accepted geoscience usage.
II-2 Selection Criteria of the Geounits The following criteria were used in selecting the specific geohazard related geounits from the general classification. That the typological individuals be detectable and recognizable in current operational civil satellite images and airphotos with a spatial resolution range of submetric to 1 km, subject to other factors conditioning observability (Sect. II-3.2). That the classification includes all the major terrestrial environments. That the units possess a compositional homogeneity with respect to a number of observable and inferred attributes. That the units be significant in broader engineering and environmental terms. The approach chosen to document the type units has been to examine airphoto coverage and satellite images of known lithologies and structures located in the various terrestrial environments. Reproductions of representative photos and images studied were thus progressively incorporated in the data sets of the geounit files as the group of illustrations in support of their textual characterizations.
II-3 Characterization of the Classification II-3.1 Purpose Geological and geomorphological interpretation and mapping requires the use of a set of descriptor codes to designate geounits. The codes best consist of combinations L.A. Rivard, Geohazard-associated Geounits, Environmental Science and Engineering, DOI 10.1007/b93844_2, © Springer-Verlag Berlin Heidelberg 2009
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of alpha-numeric symbols (Fulton 1993). The complete set of descriptors constitutes a terrain classification system. When the units are compiled as a photogeologic map these codes can also become the map legend.
II-3.4 Present Professional Context of the Classification In his advanced text on the use of remote sensing in the geological sciences Scanvic (1993) stated:
II-3.2 Mappability of Photogeologic Geounits
(the geoscience community) “… can anticipate methodological developments whose aims are to optimize the application of remote sensing techniques to the traditional activities of the (field) geologist. This applies particularly to the photo-image analyst who is attempting to gain an understanding of the geological environment of a given area. It proceeds from the normal synthesizing of multi bits of photo-image and extra-image evidence (integrated as distinct terrain units), currently the most operational photo-image interpretation method directed to the goal of an objective characterization of the terrain.” (author’s translation).
The expression of a geounit within a photo or image, and hence its mappability, is conditioned by a number of factors: sufficient distinction in lithologic composition or structure occurring in a terrain nature of the denudational processes that act or have acted on it environment in which it presently occurs spectral characteristics of geologic materials in outcrop spectral characteristics of associated vegetation or land-use spatial, spectral and temporal resolutions of the sensor system that acquired the imagery or airphoto data processing techniques employed to generate the image available background information aptitude of the person performing the interpretation Subject to the above factors, a given photogeologic interpretation or map will result in geologic information of differing specificity and accuracy.
II-3.3 Relationship to Other Image-Based Geo-Science Terrain Classifications Beginning in the 1950s a number of systematic treatments of genetic terrain units were formulated for the interpretation of stereoscopic vertical air photographs in what has become recognized as the field of Photogeology. A notable example of this is the manual by Howes and Kenk (1988). Since the advent of multispectral scanners aboard EarthObservation satellites in the 1970s, a number of texts dealing with remote sensing in geology and geomorphology have appeared. A comprehensive lexicon of lithologic geology was not central to the purposes of these works. Only Meijerink (1988) and Short and Blair (1986) contain classifications approximating the systematization introduced here. The listings of Terrain Mapping Units in Meijerink (1988) is incidental to the presentation of a GIS-compatible methodology, while Short and Blair (1986) focus on structural (rather than lithologic) patterns associated with tectonic terranes and selected denudational landform categories as they appear on the early Landsat images. Mesoscale units best resolved on airphotos are not considered in that book.
II-4 Organization of the Classification The classification is ordered in 4 lithologic and structural Divisions and 19 Genetic Groups.
II-4.1 Division 1: Magmatic Rocks and Structures The Units of this Division are primary igneous rock bodies lithified or welded. Genetic Groups of this Division include:
extrusive microlithic magmas pyro- and volcaniclastic deposits modern volcanic structures modern epiclastic deposits
II-4.2 Division 2: Sedimentary Rocks and Duricrusts This Division consists of 5 Genetic Groups:
carbonates saline and phosphatic rocks detrital rocks interbedded sequences duricrusts
Note: No metamorphic rocks appear in the present classification. As stated by Ehlen (1983) none of the three common classifications for predicting metamorphic rocks, textural, facies and formational, were found adequate for use on airphotos. Subsequent remote sensing
II 5 · Geounit Terminology
research indicates a potential possibility for identification of these rock types spectrally. Pre-Phanerozoic cratonic metamorphic rocks, like intrusive magmatic rocks, do not have geohazard relations as defined in this glossary. Non-cratonic metamorphic rocks that have geohazard relations are low-grade slate and schist. Due to their cleavages and foliations these rocks are susceptible to mechanical weathering and erosion in the same manner as siltstones and lutites among detrital and interbedded rocks.
II-4.3 Division 3: Geostructures The Structural Units are areas of deformation and displacement of rocks of Divisions 2, 3 and 4. Three structural Groups include: gravity structures fault line traces general lineaments
II-4.4 Division 4: Surficial Deposits With the exception of the basinal sediments and paraglacial groups, Geounits of this Division result from the transport and deposition in an unconsolidated state of materials eroded from the rocks and structures of the other Divisions by subaerial and marine denudation processes. Genetic Groups of Surficial Deposits include:
aeolian deposits basinal sediments fluvial system sediments marine littoral systems paraglacial geosystems periglacial-related forms mass movement materials
II-5 Geounit Terminology The Classification contains four types of typological individuals: Geostructures, Geounits, Variants and Components. They are defined and symbolically designated as follows.
II-5.1 Geostructure Definition. A Geostructure is a geounit of macro or meso scale which occurs in one of two modes:
as a portion of or all of the mass of a rock Unit which has been subjected to particular diastrophic processes as a macroscopic scale Unit in its own right Designation. A Geostructure is designated by conventional geological map symbols and by numeric codes as indicated for individual units in the Division.
II-5.2 Geounit Definition. Photogeologically a geounit is a portion of a tract of land having recognizable boundaries at appropriate photo or imagery scales and whose overall homogeneity is a function of its genesis, composition, geologic structure and relief type. A geounit approximates in conception the pedologist’s “polypedon” (Gerrard 1981, pp 6–7) and the engineering geologist’s “lithologic type” (IAEG 1981, pp 252–253). Designation. A geounit is identified by a pairing of a single upper case letter code and number, when it is part of a Group (e.g. X1 for a (undisturbed) basalt flow); or by an upper and lower case letter combination and number when it is part of a Sub-group (e.g. Ed1 for linear dunes). The alpha character codes for Genetic Groups are given in Table II.1.
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Part II · User’s Guide to the Atlas and Glossary
II-5.3 Variant
II-5.4 Component
Definition. The Variant is a photo-image distinguishable ‘facies’ resulting from the action of one of a number of geologic or environmental factors. It is genetically assignable to a parent geounit. A variety of geologic factors are illustrated in the following examples. (Refer to the classification tables for the geological designations.)
Definition. A Component is a mesoscale deposit or landform produced by genetic, structural or erosional processes. It has the following attributes:
genesis, e.g. Fv1.2, Zm1.2 diagenesis, e.g. Ps1.1, S1.2 tectonism, e.g. X1.3 relative age, e.g. Ms1.1 morphology, e.g. Mv1.1, Ed1.1 topographic site, e.g. X1.2 climatic occurrence, e.g. Bb1.1
Designation. A Variant is identified by a number following the Unit designation, (e.g. Variant S2.1 – lutite dissected facies of Unit S2 – lutites undifferentiated).
functionally integrated with the parent Unit dimensions are smaller than the parent Unit Designation. Components are indicated by a qualifying lower case letter descriptor following the Unit or Variant designation (e.g. Fv2b – a levee within a low energy alluvial deposit Unit polygon; L3c clay-salt temporal wet zone).
II-5.5 Relative Chronology Existing geological maps may enable interpreters to specify the age relations of adjacent geounits or superposed sequences of units. Suggested symbols of a general temporal nomenclature that may be used in such cases are listed in Table II.2.
Select Bibliography of Remote Sensing Technology for Geologic Interpretation
II-6 Mode of Designation of Mapped Units The degree of certainty of identification and designation of geounits that is achievable in any photo-image interpretation is conditioned by the factors listed in Sect. II-3.2: Subject to those factors, an interpreter may combine descriptor codes of the classification to geounits that have been delineated and about which he/she can be more specific. For example, composition codes may be added to structural rock units or other deposits. Some specific examples are: 2-S1.1 designates not only a cuesta in layered rocks, but more specifically one in stabilised cemented sandstones Br2.1-X1 designates an unstable high rock cliff of basalt Mv2-S2/S1.2 designates a rock avalanche in shale beds overlying a mass of weakly-cemented sandstones relative thickness and superposition of certain surficial deposits (fluvial, lacustrine, glacial) when interpretable may be designated by use of a fractional code: – Zi4/L2 designates ice wedge polygons developed on glaciolacustrine sediments – Ef1/X1 designates sand sheets flowing over a basalt flow field
References Fulton RJ (1993) Surficial geology mapping at the Geological Survey of Canada: Its evolution to meet Canada’s changing needs. Canadian Journal of Earth Sciences, vol 30, p 237 Gerrard AJ (1981) Soils and landforms. George Allen and Unwin, London Matula M (1981) Rock and soil description and classification for engineering geological mapping. Report by the IAEG Commission on Engineering Geological Mapping. Bull. IAEG no 24, pp 235–274 Meijerink AMJ (1988) Data acquisition and data capture through terrain mapping units. ITC Jour., 1988-1. Scanvic J-Y (1983) Utilisation de la télédétection dans les sciences de la terre, BRGM, France, Manuel et méthodes, no 7 Short NM, Blair RW Jr (eds) (1986) Geomorphology from Space. NASA SP 486 Varnes DJ (1974) The logic of geological maps, with reference to their interpretation and use for engineering purposes. USGS Professional Paper 837
Soeters R, van Westen C (1996) Landslides: investigation and mitigation. Special Report 247. Transportation Research Board, National Research Council, Washington, D.C. Thomas MF (1974) Tropical geomorphology. Macmillan, London, pp 158–159 Waltham T (2002) Foundations of engineering geology, 2nd edn. Spon Press, London, pp 74–75
Select Bibliography of Remote Sensing Technology for Geologic Interpretation Optical Airphotogeology Allum JAE (1966) Photogeology and regional mapping. Pergamon Press, Oxford Ehlen J (1981) The identification of rock types in an arid region by air photo patterns. US Army Corps of Engineers Topographic Labs, ETL-0261 Ehlen J (1983) The classification of metamorphic rocks and their applications to air photo interpretation procedures. US Army Corps of Engineers, Topographic Labs, ETL-0341 Ehlers M, Hermann J, Kaufmann UM (2004) Remote sensing for environmental monitoring, GIS applications and geology. Society of Photographic Instrumentation Engineering Keser N (1976) Interpretation of landforms from aerial photographs. Province of British Columbia, Ministry of Forests Lueder DR (1959) Aerial photographic interpretation. McGraw-Hill, New York Mekel JFM (1970) The use of aerial photos in geology and engineering. ITC Textbook of Photo Interpretation, vol VIII. International Institute for Aerial Survey and Earth Sciences Miller VC (1961) Photogeology. McGraw-Hill, New York Mollard JD, Janes JR (1983) Airphoto interpretation and the Canadian landscape. Surveys and Mapping Branch, Department of Energy Mines and Resources, Canada Ray RG (1960) Aerial photographs in geologic interpretation and mapping. USGS Professional Paper 373 Summerson CH (1954) A philosophy for photo interpreters. Photogrammeric Engineering 20(3):396 Townshend JRG (ed) (1981) Terrain analysis and remote sensing. George Allen & Unwin, London Tricart JS, Rimbert S, Lutz G (1970) Introduction a l’utilisation des Photographies Aériennes en Géographie, Géologie Écologie. SEDES, France Verstappen HTh (1977) Remote sensing in geomorphology. Elsevier Scientific Publishing Co., NY van Zuidam RA (1985/86) Aerial photo interpretation in terrain analysis and geomorphological mapping. Smits Publishers/ITC, The Hague von Bandat HF (1962) Aerogeology. Gulf Publishing Company, Houston, Texas
General Bibliography Electro-Optical Satellite Imageries Bell FG (1999) Geological hazards: Their assessment, avoidance and mitigation. Taylor & Francis Hayden RS (1985) Geomorphological similarity and uniqueness. NASA Conference Publ. 2312, Global Mega-Geomorphology, pp 21–22 Howard JA, Mitchell CW (1985) Phytogeomorphology. John Wiley & Sons, New York Hunt RE (2007) Geologic hazards: A field guide for geotechnical engineers. Taylor & Francis IAEG Bull (1981) No 23, pp 235–274 Kusky TM (2003) Geological hazards: A sourcebook. Greenwood Publishing Group
Amaral G (1984) Remote sensing systems comparisons for geological mapping in Brazil. Proceedings, IUGS/UNESCO Seminar, Remote Sensing for Geological Mapping, pp 91–106 Berger Z (1994) Satellite hydrocarbon exploration. Springer-Verlag, Berlin Blodget HW, Brown GF (1982) Geological mapping by use of computer enhanced imagery in Western Saudi Arabia. USGS Professional Paper 1153 de Silva S, Francis PW (1991) Volcanoes of the Central Andes. Springer-Verlag, Berlin
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Part II · User’s Guide to the Atlas and Glossary Drury SA (1987) Image interpretation in geology. Allen & Unwin, London Gupta RP (1991) Remote sensing geology. Springer-Verlag, Heidelberg Prost GL (2002) Remote sensing for geologists: A guide to image interpretation. Gordon & Breach Williams RS, Marsh SE (1983) Geological applications. Manual of remote sensing 2nd edn, Chap. 31. American Society of Photogrammetry
Radar Geology Dallemand JF, Lichtenegge J, Raney RK, Schumann R (1993) Radar imagery: Theory and interpretation. Remote Sensing Centre, Food and Agriculture Organization, United Nations, RSC Series No 67 RADARSAT International (1996) RADARSAT geology handbook, Client Services
Sabins FF (1999) Geologic mapping and remote sensing. Proceedings, Thirteenth International Conference on Applied Geologic Remote Sensing, Vancouver. pp I-41, I-42 Scanvic JY (1993) Télédétection aérospatiale et informations géologiques. BRGM, France, Manuel et méthodes, no. 24 Siegal BS, Gillespie AR (1980) Remote sensing in geology. John Wiley & Sons, New York Singhroy VH (ed) (1994) Special issue on radar geology. Canadian Journal of Remote Sensing 20(3): 197–349 Singhroy VH, Kenny FM, Barnett PJ (1989) Radar imagery for Quaternary geological mapping in glaciated terrains. Proceedings, 7th Thematic Conference on Remote Sensing for Exploration Geology, pp 591–600 Trautwein CM, Taranik JV (1978) Analytic and interpretive procedures for remote sensing data. USGS, Sioux Falls, S.D. van Sleen LA (1984) Analysis of MSS Landsat data for small-scale soil surveys in the humid tropics. Proceedings, 18th ERIM Remote Sensing Symposium, pp 1973–1982
III Part III Classification of Geohazard-Related Geounits
This classification establishes the position of geounits as typological individuals in an ordered genetic grouping of 4 lithologic and structural Divisions, 19 Groups and 32 Sub-groups. Its characterization is explained in Sect. 4, of the User’s Guide to the Atlas and Glossary and its organization is outlined in Sect. 5. The term facies has been used in the sense of the distinctive appearance of a unit or variant rather than its composition or stratigraphy. Hiatuses in the numbering of Geounit descriptor codes are due to their derivation from the comprehensive classification developed by the author. For ease of reference see Table III.1 (a reproduction of Table I.1), which contains the principal hazard types.
L.A. Rivard, Geohazard-associated Geounits, Environmental Science and Engineering, DOI 10.1007/b93844_3, © Springer-Verlag Berlin Heidelberg 2009
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Part III · Classification of Geohazard Related Geounits
Division 1 Magmatic Rocks and Structures
Division 1 · Magmatic Rocks and Structures
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Part III · Classification of Geohazard Related Geounits
Division 2 Sedimentary Rocks and Duricrusts
Division 3 · Geostructures
Division 3 Geostructures
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Division 4 Surficial Deposits · Group – Aeolian Deposits
Division 4 · Group Basinal Sediments
Division 4 Surficial Deposits · Group – Basinal Sediments
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Division 4 Surficial Deposits · Group – Fluvial System Sediments
Division 4 · Group Marine Littoral Systems
Division 4 Surficial Deposits · Group – Marine Littoral Systems
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Division 4 Surficial Deposits · Group – Paraglacial Geosystems
Division 4 Surficial Deposits · Group – Periglacial-Related Forms
Division 4 · Group Mass Movement Materials
Division 4 Surficial Deposits · Group – Mass Movement Materials
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IV Part IV Data Sets of the Atlas and Glossary of the Geounits and Variants
Division 1 Magmatic Rocks and Structures
Group X Extrusive Magmas Group P Tephra Deposits Sub-group Pf Falls Sub-group Ps Pyroclastic Density Current Deposits Group V Cenozoic Volcanic Structures Sub-group Vs Viscous Lava Structures Sub-group Vc Major Conical Structures Group A Modern VolcanicEpliclastic Deposits
General Notes of Geohazard Relations The variety of Quaternary volcanic geounits is greater than that of any other Earth subaerial rock type.The units that have geohazard relations are ordered in four Groups: Extrusive lavas. These have two Units and six Variants that are agents of eruption and deposition and are susceptible to rockfalls, sliding and slumping. Tephra deposits include two Units and three Variants; they are also agents of eruption and deposition but are highly susceptible to flowing and erosion. Volcanic structures have seven Units and seven Variants divided into viscous lava domes and conical structures proper. The viscous lavas are agents of eruption and flowing, and are susceptible to erosion,while volcanic cones and calderas are agents of eruption and are susceptible to seismicity and erosion. Epiclastic deposits consist of three Units that are the result of secondary surface processes of erosion and transportation operating on the units of the other volcanic groups. They are agents of flowing, and deposition, and are susceptible to erosion. Although these rocks occur on approximately 3% of the Earth’s land surface, their destructiveness is out of all proportion to their extent. “Fully 80% of the world’s population lives in, and presumably pays taxes to, nations with responsibility for at least one Holocene volcano” (Simkin T, Siebert L (2000) Encyclopedia of volcanoes. Academic Press, p 252).
Occurrence The patterns of occurrence of extrusive magmatic rocks on the Earth’s surface are associated with five principal tectonic settings: The linear orogenic belts of convergent tectonic plates. Divergent continental rifts, (most eruptions along divergent plate boundaries are submarine mid-ocean and are undetected). Passive intra-plate fault zones. Stationary “hot spots” of upwelling magma over which continental or oceanic portions of lithospheric plates move. Intraplate magmatism (18 illustrations) is poorly understood.
Usefulness of Volcanoes Volcanoes may however be benevolent in a number of ways by
creating new land which can be used for agricultural or urban development providing building materials (e.g. welded tuffs) contributing to the formation of certain ore deposits (sulphur,alum,boric acid,perlite) providing a source of energy (geothermal power plants)
L.A. Rivard, Geohazard-associated Geounits, Environmental Science and Engineering, DOI 10.1007/b93844_4, © Springer-Verlag Berlin Heidelberg 2009
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Division 1 · Magmatic Rocks and Structures
Group X Extrusive Magmas X1
X1 Basaltic Flows, Flow Fields, or Plateaus (Trapps) Characterization Basalt lava flows are discreet bodies of hot silicate liquids emplaced non-explosively as dynamically continuous units. Flow fields are a collection of lava flows produced by the same effusion (Kilburn 2000). They are the meso- and macroscale equivalent of regionally extensive plateau basalts. Basalt flows are erupted from central vents to produce narrow streams (Variant X1.1) or low coalescing shields, or from fissures to produce sheets in units up to 10 m thick. Edlgjá (AD 934, 30 km east of Hetkla in southern Iceland) at 30 km is the longest fissure on Earth. It is paralleled 5 km to the east by the catastrophic Lakagigar Fissure 1783 25 km in length which erupted 20 million tonnes of toxic tephra along with 565 km2 of lavas. The rate of effusion of basaltic lava, and the slope of the surface onto which it is erupted determine the morphology of the extrusions. Because of their fluidity basalt flows are capable of extending to great distances from the vent or fissure and often form thick piles as one flow builds on another to develop flow fields which can widen until halted by topography or by the end of effusion. Flows are characteristically highly jointed, the result of shrinkage during cooling in the form of both columnar and contraction joints. These flows are porous and have few surface streams. Basalt rock is itself impermeable, and where it is not highly jointed runoff develops relatively dense drainage patterns as seen in Variant X1.3. The terms Aa, Pahoehoe, and Blocky that are frequently encountered in discussions of fresh lava flows refer to a field classification of the lava crust appearance and distinct styles of flow growth. These features are poorly resolved at usual airphoto scales, i.e. 1:30 000 and smaller, however, they can be detected in radar images because of differences in surface roughness. Fresh lava flows are among the volcanic geounits that have distinctive thermal characteristics.
Geohazard Relations Property damage rather than loss of life is the principal hazard associated with basalt flows during an eruption. Secondary hazards include the expulsion of toxic gases accompanying eruption. Forest fires may be started. Thick lava blankets sterilize agricultural land for years, though the rate of land recovery is relatively fast in wet tropical zones. Weathering of columnar joints, seepage and erosion of underlying weaker rocks contribute to a susceptibility to massive slumping along plateau scarps. Early detection and monitoring of active lava flows using satellite sensors is being rapidly developed by remote sensing specialists, volcanologists and operating agencies.
Select Bibliography Cas RAF, Wright JV (1987) Volcanic successions. Allen and Unwin, London, p 73 Flynn LP, Harris AJL, Rothery DA, Oppenheimer C (2000) High spatial-resolution thermal remote sensing of active volcanic features using landsat and hyperspectral data. Remote Sensing of Active Volcanism, Geophysical Monograph 116. American Geophysical Union, pp 161–176 Hickson CJ, Edwards BR (2001) Volcanoes and volcanic hazards in Canada. In: Brooks GR (ed) A synthesis of geological hazards. GSC Bull 548:145–181 Kilburn CRJ (2000) Lava flows and flow fields. In: Sigurdsson H (ed) Encyclopedia of volcanoes. Academic Press, pp 291–305 Krafft M, de Larouzière FD (1999) Guide des Volcans d’Europe et des Canaries. Delachaux et Niestlé Macdonald GA, Abbott AI, Peterson FL (1983) Volcanoes in the sea: The geology of Hawaii. Univ. of Hawaii Press, Honolulu, pp 162–163 Peterson DW, Tilling RI (2000) Lava flow hazards. In: Sigurdsson H (ed) Encyclopedia of volcanoes. Academic Press, pp 957–971 Rothery DA, Pieri DC (1993) Remote sensing of active lava. In: Kilburn CRJ, Luongo G (eds) Active lava. University College London Press, pp 203–323 Scarpa R, Tilling RI (eds) (1996) Monitoring and mitigation of volcano hazards. Springer-Verlag, Heidelberg Smith K (1996) Environmental hazards, 2nd edn. Routledge, London, pp 161–165 Walker GPL (1973) Lengths of lava flows. Phil Trans R Soc London, A274:107–118
X1 · Basaltic Flows, Flow Fields, or Plateaus (Trapps)
Fig. X1-1. Source. USGS Comments. The block diagram depicts the characteristic mode of effusion and extended flow of successive sheets of basaltic lava from a fissure to form thick piles as one flow builds on another. See a ground photo of such a pile in Fig. X1-3.
Fig. X1-2. Source. USGS Comments. The photo shows a basaltic lava flow encroaching on a road in the Hawaii Volcanoes National Park.
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Fig. X1-3. Source. Courtesy of Natural Resources Canada, GSC 74079 Comments. Photo shows a succession of Tertiary basalt flows with characteristic columnar jointing at Mission Creek, British Columbia.
28 Division 1 · Magmatic Rocks and Structures
X1 · Basaltic Flows, Flow Fields, or Plateaus (Trapps)
Fig. X1-4. Location. Geographic. 03°40' E, 45°04' N, south central France Source. LAR, October 1976 Comments. View of a road cut 22 km northwest of Le Puy in the Massif Central that exposes Upper Pleistocene brecciated basalt 15 000 BP overlying Lower Pleistocene, 1 500 000 BP lacustrine fine sands, reddened at the lava contact. This site is 95 km southeast of the columnar basalt of Fig. X1-6. The regional geologic context of this figure is described in Fig. Pf1-6. See also Figs. Vs1-2 and Vs1-3.
Fig. X1-5. Source. Hamblin WK (1974) Late Cenozoic volcanism in the Western Grand Canyon. In: Breed WJ, Road EC (eds) Geology of the Grand Canyon. Northern Arizona Society of Science and Art Inc., p 166, fig 17 Comments. An air perspective view shows typical basalt flows in one of the areas of Cenozoic volcanism that occur around the margins of the Colorado Plateau. The location is near the western edge of the Plateau, north of the Colorado River. The flows were extruded from numerous craters that lie from 100 to 200 m above the underlying Lower Triassic shales. The dark mound on the left is a scoria/ash cone.
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Division 1 · Magmatic Rocks and Structures
Fig. X1-6. Source. Deffontaines P, Delamarre MJ-B (1958) Atlas Aérien, France, Tome III. Gallimard, p 152, fig 253 Comments. An air view at Bort in the western part of the Massif Central of France shows the characteristic columnar structure of a 90 m high basalt flow. The flow is Tertiary phonolite, an outlier of the extensive Cantal volcanic centers to the east. This site is 95 km northwest of the brecciated basalt of Fig. X1-4 and 60 km southwest of the trachyte dome of Fig. Vs1-3. A description of the regional geologic context of this figure is given in Fig. Pf1-6.
Fig. X1-7.
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Location. Geographic. 130°04' W, 57°28' N, north central British Columbia Klastline Plateau Geologic. Stikinia Terrane of intermontane belt of Cor-dillera Vertical Airphoto/Image. Type. b/w, pan airphoto Scale. 1:30 000 approx Acquisition date. Not given Source. Base Mapping and Geomatic Services Branch, Ministry of Sustainable Resources, Government of British Columbia, Canada. BC 1251-105, 104 Comments. This stereomodel in the northern Skeena Mountains shows the dissected margin of Late Cenozoic lava flows from adjacent Edziza volcanic complex in Edziza Provincial Park (Fig. Vc2-4) or from local fissures. The massive dissected rock unit underlying the lavas is Mid to Upper Jurassic sedimentary rock. An Ms3 rock slump occurs along the west-facing scarp. The Zm2 rock glaciers in north-facing cirque scarps are in the present zone of Alpine permafrost. Their situation near the upper limit (2 000 m) of semi-independent glacier systems of the late Wisconsinan (Würm) Cordilleran glaciation suggests that they may also be relics of that time.
X1 · Basaltic Flows, Flow Fields, or Plateaus (Trapps)
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X1.1 · Local Slope Flows ▼
Fig. X1-8. Location. Geographic. 03°22' E, 43°40' N, Languedoc, France Geologic. Southern Jurassic Causse basins Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 30 000 Acquisition date. 1970 Source. IGN–Photothèque Nationale, France Comments. The stereomodel shows the Po/Pl basalt flows surrounding the Salagou hydro-electric power reservoir. They are part of the regional Escandorgue fissure eruptions related to Neogene volcanic activity of the Massif Central 100 km to the north. The area consists of Permian/ Triassic detrital sediments on the southern periphery of the limestone Causses. Four Ms1.1 rock slides are associated with the basalt scarps. Cultivated terraced fluvial deposits fill the Lorgue River valley.
X1.1 Local Slope Flows Characterization A local slope flow extends for long distances as a relatively narrow stream that outpours from fissures or extends from a vent well beyond the steep depositional slopes of stratovolcanoes. In response to slope relief the flow will channel into existing erosional ravines and may spread out at valley margins. The morphology of young slope flows reflects the process of flow. In addition to Component ‘b’ marginal flow levees of this Variant flow lines, superimposed flows and gas pocket depressions combine to produce characteristic rugged flow surfaces. These relief details are detected in both airphoto and satellite imagery.
Geohazard Relations In addition to the hazards related to the parent unit, slope flows that come into contact with ice and snow can generate Mf3 debris-mud flows. Kilburn (2000) has developed flow equations related to slope angle which provide reliable estimates of potential flow length and can be used for preparation of hazard maps.
Reference Kilburn CRJ (2000) Lava flows and flow fields. In: Sigurdsson H (ed) Encyclopedia of volcanoes. Academic Press, pp 291–305
Select Bibliography Eisbacher GH, Clague JJ (1984) Destructive Mass Movements in High Mountains: Hazard and Management. GSC Paper 84–16, pp 29–36 Hulme G (1974) The interpretation of lava flow morphology. Geophys J R Astr Soc 39:361–383 Scott WE (1989) Volcanic and related hazards. In: Tilling RI (ed) Volcanic hazards. Short course in geology: Volume 1. Presented at the 28th International Geological Congress, Washington D.C., American Geophysical Union, pp 9–22
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X1.1
Division 1 · Magmatic Rocks and Structures
Fig. X1.1-1. Location. Geographic. 130°32' W, 57°51' N, north central British Columbia Geologic. Stikinia Terrane of Intermontane Belt of Cordillera Vertical Airphoto/Image. Type. b/w pan, stereogram Scale. 1: 40 000 Acquisition date. August 1949 Source. Courtesy of Natural Resources Canada, NAPL, A12184, 131, 132 Comments. The stereomodel shows the lower 5 km of a 13 km long by 1 to 2 km wide ropy basalt slope flow. This flow is on the north slope of Edziza Volcano, 2 590 m, pictured in the stereo photo pair of Fig. Vc2-5. Figure Vc2-4 is a perspective view of the volcano. The flow, which postdates the last episode of regional glaciation, descended 1 160 m in elevation from its point of origin. The relatively low resolution of the photo print fails to reveal that there are sparse stunted trees rooted in pockets of soil among the blocks of lava which are as old or older than the trees in the adjacent mature forest. The trees on the soilless flow surface have a slow rate of reforestation.
Fig. X1.1-2.
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Location. Geographic. 137°22' W, 62°55' N, central Yukon Geologic. Nisutlin Terrane of Omineca Cordilleran Belt Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 40 000 Acquisition date. Not given Source. Courtesy of Natural Resources Canada, NAPL, A12106-129, 130 Comments. Two slope flows in opposite directions and a valley flow that issued from a local breached stratovolcano are pictured in this stereomodel 40 km west of Pelly Crossing. The barren volcano has evidently erupted recently from a vent that existed earlier and was the source of the mainly vegetated older flows. (The white stripe across the photo is a blemish in the original photo negative.)
X1.1 · Local Slope Flows
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Division 1 · Magmatic Rocks and Structures
Fig. X1.1-3. Location. Geographic. 103°30' E, 11°30' N, Southwest Cambodia Geologic. Lower Jurassic craton cover sandstones Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 35 000 Acquisition date. 5 November 1958 Source. Journal Photo Interprétation, Editions ESKA, Paris, 67-6.3 Comments. A stereomodel shows that the characteristic and diagnostic morphology of certain Cenozoic photogeologic
units permits them to be detected and identified under dense forest cover. Location is in the Elephant Chain, of the Cardomon Mountains. The crater area of the Vc1 volcano and the X1.1 basalt slope flows are distinguishable. It is noted that such geologic unit recognition under forest cover also applies to the surrounding S1 interbedded sandstones. The lavas are one of three local outpourings – Ambel, Tatey, or Veal Veng, 150 km west of Phnom Penh. They are probably associated with tectonic movements at the western end of the Indochina Uplift.
X1.1 · Local Slope Flows
Fig. X1.1-4. Location. Geographic: 67°53' W, 22°50' S, southwest Bolivia. Vertical Airphoto/Image. Type. TM Acquisition date. 2007
Source. MDA EarthSat. Comments. This satellite image shows well-developed youthful lava flows that extend up to 6 km on the flanks of Vc1 Licancabur Volcano (5 916 m) in the Cordillera Occidental on the Chilean border.
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X1.2
Division 1 · Magmatic Rocks and Structures
X1.2 Local Valley Flows Local valley flows are further characterized by two Components: X1.2a – residual lava ridge X1.2b – Interstratified flows and fluvial-lacustrine sediments
Characterization A valley flow travels down the valley axis, filling it partially or wholly, burying fluvial deposits and causing some streams displaced by the lava to etch out new channels along the margins of the encroaching flow.
Geohazard Relations Local valley flows can dam the valley and tributaries and cause upstream flooding. Many lava flow dams are so permeable that the impounded lakes do not overflow; the dams remain stable prolonging the flooding.
Select Bibliography Scott WE (1989) Volcanic and related hazards. In: Tilling RI (ed) Volcanic hazards. Short course in geology: Volume 1. Presented at the 28th International Geological Congress, Washington D.C., American Geophysical Union, p 9
See also Unit X1.1.
Fig. X1.2-1. Source. Roche Brésole J (undated) Parc Naturel Régional des Volcans d’Auvergne. Copyright éditions G. de Bussac. Dessin Roche et Brésole, p 51 Comments. The schematic block diagram shows the topographic relationships of Variants of basaltic lava flows.
X1.2 · Local Valley Flows
Fig. X1.2-2. Source. Green J, Short NM (eds) (1971) Volcanic Landforms and Surface Features. Springer-Verlag, plate 139A Comments. An air perspective photo shows a blocky Quaternary lava valley flow in the volcanic Modoc Plateau of northern California. The flow surface is about 30 m above the surrounding terrain which lies in one of a number of regional block-faulted basins. The smooth white deposits in foreground are Pf1 ash.
Location. Geographic. 119°50' W, 52°08' N, southern British Columbia Geologic. Barkerville Terrane of Omineca Cordilleran Belt Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 62 000 Acquisition date. Not given Source. Courtesy of Natural Resources Canada, NAPL, A133318-92, 93 Comments. The lava valley flows of Quaternary Clearwater basalts in this stereomodel of Upper Paleozoic metasediments in Wells Gray Provincial Park erupted from a vent in the upper left corner of the interpreted photo and flowed 60 km down valley.A scoria/ash cone has erupted from the vent more recently. The lake portion visible behind the vent site resulted from the damming of the stream (File Creek) by the lavas. Two prominent fault-suggestive geolineaments have been drawn.
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Fig. X1.2-4.
Location. Geographic. 130°37' W, 56°45' N, northern British Columbia Geologic. Stikinia Superterrane of Cordilleran Intermontaine Belt Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 50 000 Acquisition date. Not given Source. Courtesy of Natural Resources Canada, NAPL, A12198 – 170, 171 Comments. This stereomodel in the lower Iskut River valley shows forested Quaternary lava flows that issued from a 1 km diameter cone located near the base of a steep mountain slope marked by both old and recent-appearing mass movements and a strong geolineament 1 km south of the failures. The flows fill the valley floor and continue 15 km beyond the western edge of the model. This figure is located 40 km south of Fig. Fv1.1-5.
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Fig. X1.2-3.
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Division 1 · Magmatic Rocks and Structures
Fig. X1.2-3. (Caption on p. 39)
X1.2 · Local Valley Flows
Fig. X1.2-4. (Caption on p. 39)
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Division 1 · Magmatic Rocks and Structures
X1.3 · Disturbed Dissected Basalts ▼
Fig. X1.2-5. Location. Geographic. 05°11' E, 22°58' N, southeast Algeria Geologic. Weathered Upper Proterozoic granites of Hoggar cratonic massif Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 87 000 Acquisition date. 1969 Source. IGN–Photothèque Nationale, France Comments. The stereomodel at Tit, 40 km northwest of Tamanrasset shows narrow Tertiary (possibly Eocene) residual lava ridges extending 14 km along the margin of a wadi valley. They are erosional remnants of flows from sources eastward in the Atakor volcanic massif.
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jointed flows and segments display relatively dense surface drainage systems and dissection. Resistant units of older flows may be disproportionately preserved, but in general “Only those relatively undeformed flows, mainly of Tertiary age and younger, are readily identifiable from aerial photographs without some knowledge from ground surveys.” (Ray 1960). Pre-Cenozoic and ancient weathered, dissected, variably deformed and metamorphosed successions can be significantly modified in their morphologic appearance.
Geohazard Relations The geohazards associated with solidified, stabilized flows relate principally to sliding, slumping and rockfalls.
Reference
X1.3 Disturbed-Dissected Basalts
Ray RG (1960) Aerial photographs in geologic interpretation and mapping, USGS Professional Paper 373, p 17
Characterization
Select Bibliography
The more permeable highly jointed flows tend to be more resistant to weathering and erosion in contrast to other crystalline rocks. As a consequence the more impermeable, less
Drury SA (1987) Image interpretation in geology. Allen & Unwin, London, pp 81–83 von Bandat HF (1962) Aerogeology. Gulf Publishing Co., Houston, Texas, pp 142–144
Fig. X1.3-1. Location. Geographic. 70°21' W, 23°37' S, north Chile Source. Rich JL (1942) The Face of South America. In: Weaver JC (ed) Special Publication No. 26. American Geographic Society, New York, photo 233 Comments. This air perspective view southward 10 km northeast of the port of Antofogasta shows a monoclinal
fault block of thick Lower Jurassic lava sequences of the Sierra Ancla on the arid north coast. The disturbed beds are part of the 1 000 km long Lower Cretaceous Atacama Fault System which parallels the subducting Mazca Plate from Iquique at 21° S to La Serena at 30° S. Renewed tectonic deformation in the fault system in this latitude occurred during the last subduction earthquake 30 June 1995.
X1.3
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Division 1 · Magmatic Rocks and Structures
X1.4 · Dissected Alkaline Basalts ▼
Fig. X1.3-2. Location. Geographic. 65°43' W, 21°26' S, southern Bolivia Geologic. Polygenetic Cordillera oriental Vertical Airphoto/Image. Type. b/w pan, stereogram Scale. 1: 50 000 Acquisition date. 30 August 1967 Source. Cordova EV (1992) La Fotografia Aerea y su Aplicacion a Estudios Geologicos y Geomorfologicos – Tomo II. Universidad Mayor de San Andres, La Paz, Bolivia, modelo estereoscopico 94 Comments. This stereomodel shows the rugged upland topography of dissected Tertiary basalts and dacites of a local extrusion associated with the rift-like Tupiza Valley containing shaly and sandy S2.1 Ordovician sediments.
X1.4 Dissected Alkaline Basalts Characterization Denudation and weathering produces the distinctive aspects of this facies from the dissected facies X1.3. The distinctiveness is due to enhanced dissection resulting from in-situ deep chemical weathering in humid tropical environments (see Mc1). Typical morphology is steepsided ridges and spurs and generally straight steep slopes. In engineering work the weathered rock and residual soil can be ripped with power equipment.
Geohazard Relations Fluvial erosion of impermeable soils and a number of mass movements are associated with the relative instability of this facies: Creep, Mc1; Surficial material debris slides, Ms2; and Debris-mud flows, Mf3. The possible irregularity of the weathering front can be an important factor in engineering excavations.
References Drury SA (1987) Image interpretation in geology. Alen & Unwin, London Ray RG (1960) Aerial photographs in geologic interpretation and mapping. USGS Professional Paper 373
Select Bibliography Bellamy JA (1986) Papua New Guinea inventory of natural resources,population distribution and land use. Natural Resources Series No. 6, Division of Water and Land Resources. CSIRO, Australia, pp 59–61, 70–81 Blake DH, Paijmans K (1973) Landform types and vegetation of Eastern Papua. Land Research Ser. No. 32, CSIRO, Australia, pp 36–40 Dizier JL, Olivier L (1982) Photo-Interpretation et Cartographie en Haiti. Faculté d’Agronomie et Médecine Vétérinaire,Université d’État d’Haiti, pp 185, 191, 265
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Drury SA (1987) Image interpretation in Geology. Alen & Unwin, London, pp 81–82 Erb DK (1982) Geologic remote sensing in “difficult terrain”, photogeomorphology and photogeology in the humid tropics. Proceedings, Second Thematic Conference, Remote Sensing for Exploration Geology, ERIM, pp 365–374 Hardjoprawiro S, Sidarto (1987) The geology of the area surrounding Lake Kerinci Indonesia as interpreted through SIR-B imageries. Geological Research and Development Centre, Bandung Macdonald GA, Abbott AI, Peterson FL (1983) Volcanoes in the sea: The geology of Hawaii. University of Hawaii Press, Honolulu Thomas MF (1974) Tropical geomorphology. Macmillan, London
Photogeological Note Photogeologically Cretaceous volcanic X1.4 and Tertiary sedimentary Kp1 rocks occurring in disturbed settings have proven difficult to distinguish and delineate on both airphotos and satellite images. The problem has been defined as follows: “Only those relatively undeformed flows, mainly of Tertiary age and younger, are readily identified from aerial photographs without some knowledge from ground surveys … where flows have been strongly tilted, folded, or otherwise disturbed, recognition and interpretation from aerial photographs may be extremely difficult or impossible.” (Ray 1960, p 17). “Lavas, unless they are undissected and show distinctive surface features, are difficult to distinguish from sediments with which they may be interbedded.” (Drury 1987, p 81). To illustrate the difficulty, the following are the main photo and image morphologic criteria observed to distinguish lithologies in Figs. X1.4–6 and 9. The intense dissection of the volcanic rocks. The higher, less dissected plateau-like condition of the carbonates. The conformable stratigraphic position of the carbonates overlying the volcanics. The presence of apparent solution features on plateau surfaces. Slope failure at plateau margins suggesting contact with weaker underlying volcanics. Similar failures are also characteristic of basalt plateau scarps. Divides in dissected carbonate areas are less frequent and less sharply defined than in the volcanics. Some dissection zones in the volcanics, which have not been isolated in this interpretation, display a form that is very suggestive of pyroclastic materials: knife-edge ridges and steep uniform sideslopes.
X1.4
Division 1 · Magmatic Rocks and Structures
Fig. X1.4-1. Source. This picture has been reproduced with the kind permission of the Commonwealth Scientific and Industrial Research Organisation (CSIRO). The original picture appears at Bellamy JA (ed). Inventory of Natural Resources, Population Distribution and Land Use, Papua New Guinea. CSIRO Natural Resources Series No. 6, p 59, fig 5.31 © CSIRO 1986 Comments. An air perspective photo shows the dissection and weathering of alkaline volcanic rocks in a tropical humid climate. These are massive Oligo and Miocene plate tectonic island arc basalts and andesites at 146°06' E, 05°50' S 140 km northwest of Lae in the Finisterre Range of the eastern PPNG coast ranges. Many landslides are present.
Fig. X1.4-2. Source. Macdonald GA and others (1983) Volcanoes in the Sea, 2nd edition. University of Hawaii Press, Honolulu, p 210, fig 10.10 Comments. The air view shows strongly dissected Tertiary basalts at the east end of Molokai Island. In the lower right an airstrip has been emplaced on an undissected interfluve. Molokai is 15 km north of Lanai Island of Fig. Vc3.4-3.
Fig. X1.4-3.
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Location. Geographic. 156°38' W, 20°49' N, Hawaii Vertical Airphoto/Image. Type. Colour infrared airphotos Scale. 1: 165 000 Acquisition date. Not given Source. Upper photo – NASA Lower photo – Lillesand TM, Kiefer RW (1979) Remote Sensing and Image Interpretation. ©John Wiley & Sons, plate IV. Reproduced with permission.
X1.4 · Dissected Alkaline Basalts
Comments. These two photos of the same locality on the southwest coast of west Maui show the deep dissection of Tertiary alkaline surficial basalt flows, (Wailuku Series). The dissection reflects the relatively high surface runoff on more weathered, less permeable lavas. West Maui is a Vc2 shield volcano with a Vc3.4 caldera in its center. The inset frame on the vertical photo shows the coverage of the air perspective stereo pair. Slightly brighter small Vs1 trachyte domes with a lo-
cally anomalous morphology are visible just west of the fan on both photos. The cloud cover 10 km inland in the caldera vicinity is over the red coloured 1 500 m elevation West Maui Forest Reserve with average annual rainfall of 1 000 cm. The barren-looking hills near the coast receive 40 to 80 cm annual rain. This bioclimatic pattern is typical of Hawaiian Islands with their northeast trade winds. Red zones along the coast are irrigated plantations (pineapple/sugar). West Maui is 15 km east of Lanai Island of Fig. 17.2-2.
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Division 1 · Magmatic Rocks and Structures
Fig. X1.4-4. Location. Geographic. 55°37' W, 27°46' S, northeast Argentina Geologic. Volcanic craton cover of southern diabase Brazilian Shield Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1 : 33 000 Acquisition date. 14 March 1962 Source. Journal Photo Interprétation. Editions ESKA, Paris, 64-4.3 Comments. Mesozoic basalt flows and Variants are delineated in this stereomodel oriented northeast/southwest in
a partly forested area in the vicinity of Posadas Missiones Province. Areas of X1 plateau basalts are surrounded by forested slopes labelled X1.1. These areas may just be slopes of the plateau sequences rather than distinct slope flows. The valley areas consist of X1.4 weathered and possibly alkaline basalt. The bright unforested area in the upper plateau area is a zone of shallow unweathered basalt that may be abandoned agricultural land. The cleared land in the weathered basalts in lower left of the model is interpreted as agricultural use.
X1.4 · Dissected Alkaline Basalts
Fig. X1.4-5. Location. Geographic. 09°15' E, 05°45' N, southwest Cameroon Geologic. Cretaceous tectonic trough Vertical Airphoto/Image. Type. b/w infrared, stereo pair Scale. 1: 50 000 Acquisition date. Not given Source. IGN–Photothèque Nationale, France Comments. This stereomodel near Mamfé shows a Cretaceous lava flow overlying Cretaceous detrital sediments. The lavas are associated with volcanic massifs of the regional Mount Cameroon rift valley type trough.
The distinction between the respective morphologies is subdued by the dense forest cover. The S1K area has low, rounded, uniform topography. The weathered mantle relief of the X1-4 Cn higher overlying basalts has slightly coarser textured and dissected terrain. Lake Nyos (10°33' E, 05°48' N) occupies the crater of one of a number of Vc3 calderas that occur in this range. In August 1986, a rapid, massive release of carbon dioxide from this lake killed over 1 700 people. Most victims were asphyxiated in the cold CO2 cloud that travelled a gaseous density current from the lake down the valleys.
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Division 1 · Magmatic Rocks and Structures
Fig. X1.4-6. (Caption on p. 52)
X1.4 · Dissected Alkaline Basalts
Fig. X1.4-7. (Caption on p. 52)
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Division 1 · Magmatic Rocks and Structures ▼
Fig. X1.4-6. Location. Geographic. Southwest Haïti Geologic. Greater Antilles Disturbed Belt of Caribbean Plate Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 44 000 Acquisition date. Not given Source. IGN–Photothèque Nationale, France Comments. A stereomodel in the Massif de la Selle 30 km southwest of Port au Prince covers high relief Lower Cretaceous basaltic rocks whose strong dissection is characteristic of alkaline facies with weathered mantle in tropical climate. The Landsat subscene of Fig. X1.4-9. shows the regional setting of these lavas. Old rock slides (Ms1.1) and the karst terrain in which they occur are delineated.
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Fig. X1.4-7. Location. Geographic. 106°05' E, 15°07' N, south Laos Geologic. Craton cover sediments Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 35 000 Acquisition date. 1981 Source. Personal archive Comments. The stereomodel on the southwest part of the Bolovens Plateau shows X1.4-PL flows of weathered alkaline Pleistocene basalts in the northern half of the model associated with north-northeast trending fractures. Surface streams have eroded gullies parallel to local flow lines. The flows have developed good iron-rich soils and are relatively densely cultivated. In marked contrast, the poorer soils of W4-J Mid Jurassic quartzitic sandstones of the plateau to the south are forested and uncultivated. The location of the photos is shown on the satellite image of Fig. X1.4-8.
X1.4 · Dissected Alkaline Basalts
Fig. X1.4-8. Location. Geographic. 106°E, 15°10' N, south Laos Vertical Airphoto/Image. Type. Landsat Acquisition date. 2005 Source. MDA EarthSat Comments. This image of the southwest portion of the Bolovens Plateau in southern Laos shows bright green basaltic lava flowing off the plateau through a depression between plateau scarps. Lower Pleistocene basalts issued from north-east trending fissures cover 75 km of the plateau at an elevation of 1 000 to 1 200 m with flows occupying the valleys that radiate from the plateau center.
The underlying plateau, which is exposed in the scarps and eastward in Fig. W1-5 consists of Mid-Jurassic sedimentary rocks epeirogenetically uplifted at the time of the lava outflows. The vegetation cover is monsoonal humid tropical forest. The Mekong River near Paksé is in the lower left. The inset frame locates the stereo photopair of Fig. X1.4-7. Some land use changes are observable within this frame area in the quarter century following the air photography. The agricultural occupance visible on the lavas in the airphotos is not evident in the satellite image, but land clearing can be seen on the plateau basalts in the lower right of the photo cover frame.
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Division 1 · Magmatic Rocks and Structures
Fig. X1.4-9. Location. Geographic. 72°30' W, 18°24' N image center, south Haiti Vertical Airphoto/Image. Type. MSS 80 m resolution Scale. 1: 250 000 Acquisition date. January 1979 Source. USGS
Comments. The typically strongly dissected Lower Cretaceous alkaline lavas in a tropical humid climate are detectable and delineated on this Landsat image. The massif is bordered to north and south by Kp1 limestones. This figure shows the regional setting of the stereo photopair of Fig. X1.4-6. Altitudes in the X1.4 unit range from 600 m a.s.l. to 1 500 m a.s.l. at the east. Bordering limestone ridges are about 600 m elevation.
X2 · Interbedded Lavas and Pyroclastics
X2 Interbedded Lavas and Pyroclastics
ments produces a distinct topography displayed in Variant X2.2.
Characterization
Geohazard Relations
The basic characteristic of interbedded lavas and pyroclastics is a plateau-like sequence of horizontally bedded and low dipping strata in a terraced or stair-stepped pattern of compound slopes. Scarps and gentle slopes develop on resistant and weak beds respectively. Lavas have scarps and steep slopes. Non-cohesive unwelded tuffs have gentler slopes and a wider outcrop belt. In lavas the ground slope is governed by its composition, while in the tuffs it is governed by grain size. Interbedded sedimentary rocks (W1) and interbedded sedimentary and volcanic rocks (W2) have photogeologic characteristics similar to this geounit. Distinction of X2 is supported by close association with other volcanism. As with Variant X1.4, climatic denudation in more humid tropical environ-
Interbedded flows are highly unstable due to the presence of the weak tuff beds. Undermining of the tuffs can lead to collapse or landsliding of the overlying lavas (e.g. see Fig. Bc4–6). Vertical jointing in the lavas presents a potential for large slides along the scarps. Tunnelling through these rocks is hazardous because of the risk of collapse.
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Fig. X2-1.
Source. Way DS (1978) Terrain Analysis 2nd edn. Dowden, Hutchinson & Ross, p 166, fig 6.9 Comments. A schematic section shows the characteristic differential erosion of interbedded resistant lavas and weaker pyroclastic beds.
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Fig. X2-2.
Location. Geographic. 05°32' E, 23°15' N, southeast Algeria Source. LAR, April 1974 Comments. The photo shows a repetition of beds of Miocene basalts and tephra at 2 500 m elevation on the eastern side of the Ilamane viscous dome in the 2 150 km2 Atakor volcanic Highland of the Hoggar Cratonic Massif. The lavas and tephra cover a granitic and gneissic basement. The angular rubble in the foreground is probably frost riven. Location is just off the western edge of the map of Fig. Vc4-1.
Select Bibliography Drury SA (1987) Image interpretation in geology. Allen & Unwin, London, p 81 Rognon p (1967) Le Massif de l’Atakor et ses Bordures. Centre National de la Recherche Scientifique, Paris, pp 166–169 Way DS (1978) Terrain analysis: A guide to site selection using aerial photographic interpretation, 2nd edn. Dowden, Hutchinson & Ross, Stroudsburg, pp 166–175
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X2
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Division 1 · Magmatic Rocks and Structures
Fig. X2-3. Location. Geographic. 66°52' W, 19°25' S, southwest Bolivia Vertical Airphoto/Image. Type. TM Acquisition date. 2007
Source. MDA EarthSat. Comments. This satellite image shows a deposit of Tertiary interbedded lavas and tephra of the Los Frailes Formation on the Altiplano at the Laguna Sevaruyo near Rio Mulata.
X2 · Interbedded Lavas and Pyroclastics
Fig. X2-4. Location. Geographic. Western USA Vertical Airphoto/Image. Type. b/w pan, stereogram Scale. 1: 31 680 Acquisition date. 1946 Source. Personal archive Comments. The code “B” in this stereomodel points to faint bedding traces in interbedded rhyolite and tuff at an unspecified location.
Fig. X2-5. Location. Geographic. Southern Arizona Vertical Airphoto/Image. Type. b/w pan, stereogram Scale. 1: 31 680 Acquisition date. Not given Source. Personal archive Comments. This stereomodel shows the typical erosion response pattern of resistant lavas, X2a, and weaker pyroclastics X2b.
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X2.1
Division 1 · Magmatic Rocks and Structures
X2.1 Interbedded Lavas and Pyroclastics, Disturbed Facies
have the continuity of interbedded sedimentary and volcanic rocks.
Characterization
Geohazard Relations
This variant show a dissected relief in stereo-photos, and dips of lava beds are discernable. The sequences do not
See Geounit X2.
Fig. X2.1-1. Vertical Airphoto/Image. Type. b/w pan, stereogram Scale. 1: 25 000 Acquisition date. Not given Source. Personal archive Comments. These stereomodels of localities in western State of Utah, USA show occurences of deformed interbedded Tertiary andesites and tuffs on the northwest margin of the Colorado Plateau. Diagnostic evidence of interbedding in such areas becomes obscured, but other associated indicators are generally present. In the upper model, the micro relief and topo site of exposed tuffs, labelled “b”, allows their delineation. In the higher, more rugged “a” area some bedding traces are visible and local mass movements at contacts are indicative. In the lower model diagnostic indicators are lacking, the single rock slump is inconclusive. Field evidence is required in such areas.
X2.1 · Interbedded Lavas and Pyroclastics, Disturbed Facies
Fig. X2.1-2. Location. Geographic. Southeast Arizona Vertical Airphoto/Image. Type. b/w pan, stereogram Scale. 1: 31 680 Acquisition date. Not given Source. Personal archive Comments. These stereomodels are in areas of disturbed and dissected interbedded Tertiary lavas and pyroclastic rocks on the southern margin of the Colorado plateau. Diagnostic features are limited by the structural and erosive morphology, but some bedding traces are evident at “B” in the upper model and at “1” in the lower. The contact drawn at “2” in the lower model is between interbedded lavas and pyroclastics that overlie basalt, possibly in a thrust fault relation. The gully area in the upper model is in pyroclastics.
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X2.2
Division 1 · Magmatic Rocks and Structures
X2.2 Interbedded Lavas and Pyroclastics, Dissected Facies
aerial photographs without some knowledge from ground surveys”.
Characterization
Geohazard Relations
Lava beds tend to be indistinguishable in strongly dissected sequences of this geounit. The greater the proportion of pyroclastics present, the greater the dissection. Stereo-photo interpretation reveals a morphology similar to that of dissected alpine and pre-alpine orogenic batholiths (masses of intrusive igneous rocks), and dissected facies of non-cratonic massive metamorphic rocks. Ray (1960) stated “Only those relatively undeformed flows, mainly of Tertiary age and younger, are identifiable from
See Geounit X2.
References Ray RG (1960) Aerial photographs in geologic interpretation and mapping. USGS Professional Paper 373, p 17
Select Bibliography See Geounit X2.
Fig. X2.2-1. Vertical Airphoto/Image. Type. b/w pan, stereogram Scale. 1: 31 680 Acquisition date. Not given Source. Personal archive Comments. The stereomodel is of a locality in the Central Rocky Mountains of Wyoming, USA, probably in the Tertiary Absaroka Mountains in the northwest corner of the state. The interpretation, based on relative differences of erosional relief, makes a tentative distinction between areas composed mainly of breccias – b, and those of basalt flows – a. White codes “D” indicate intrusive dykes, not tilted basalts. These mountains were extensively glaciated, obscuring lithological contacts in addition to the erosion normally resulting from steep slopes in high relief.
Fig. X2.2-2.
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Vertical Airphoto/Image. Type. b/w pan, stereogram Scale. 1: 40 000 Acquisition date. Not given Source. van Zuidam RA, van Zuidam-Cancelado FL (1978–1979). ITC Textbook of Photo-Interpretation Vol.VII. Use of aerial detection in geomorphology and geographical landscape analysis. Chapter 6 Terrain Analysis and Classification Using Aerial Photographs. A geomorphological approach. International Institute for Aerial Surveys and Earth Sciences (ITC), The Netherlands, p 79, photo 45 Comments. A stereomodel shows dissected tephra and interbedded minor lavas at an unidentified location in a Far East humid tropical climate.
X2.2 · Interbedded Lavas and Pyroclastics, Dissected Facies
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X2.2 · Interbedded Lavas and Pyroclastics, Dissected Facies ▼
Fig. X2.2-3.
Location. Geographic. 81°17' W, 08°29' N, western Panama Geologic. Isthmus Ranges volcanic arc Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 60 000 Acquisition date. March 1979 Source. Personal archive Comments. The stereomodel covers the upper reaches of the Rio Cañazas at a general elevation of 600 m a.s.l. The continental divide is in the forested mountains at the north end of the photo cover. The model displays the intense dissection in a dry climate (100–200 cm av. annual rainfall) typical of weak, interbedded, in this case Miocene, lavas and pyroclastic sediments, with the latter probably dominant. The red X2a areas are mapped as inliers of the more resistant lavas on the overlay. Two Ms1 rock slides are also delineated. See also Figs. Ms3-4 and Ms3-5.
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Division 1 · Magmatic Rocks and Structures
Group P Tephra Deposits Sub-group Pf Falls Pf1
Pf1 Pyroclastic Falls Characterization Pyroclastic falls are a rain-out of clasts during an explosive eruption of high viscosity magmas. The geometry and size of deposits reflect the eruption column height and the velocity and direction of winds. Clasts fall back to Earth at varying distances downwind from the source depending on their size and density. All fall deposits show some diminution in grain size between vent proximal and distal areas. Agglomerate and breccia pyroclasts are >64 mm; lapilli and scoria are between 2 and 30 mm, while ash is 8 500 km2, Frailes ignimbrite plateau at an average elevation of 4 500 m, west of Potosi. Radiometric ages for the flows range from 20 Ma to 7 Ma. Characteristic radial fluting patterns are conspicuous. White codes indicate local place names:. HP is Cerro Huanapa Pampa; NM is a Holocene Nuevo Mundo complex; CN is Cerro Condor Nasa. Because of sheer size the existence of this structure and other large silicic calderas as Pastos Grandes of Fig. Vc3.3-3 and Cerro Galan of Fig. Vc3.3-4 were only discovered by the synoptic view provided by Earth Observation satellites in the mid to late 1970s when they became immediately obvious.
Ps1.1 · Macroscopic Ignimbrite Outflow
Fig. Ps1.1-7. Location. Geographic. 118°30' W, 37°27' N at inset frame, central California Vertical Airphoto/Image. Type. MSS 80 m resolution Scale. 1: 1 000 000 Acquisition date. 04 October 1979 Source. USGS Comments. This Landsat image is annotated to show the regional setting of the Bishop Tuff of Fig. Ps1.1-3 airphoto. The inset frame locates the coverage of the airphoto. The tuff originally extended 40 km northward to Mono Lake, but has been partly eroded or covered by more recent volcanic deposits.
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Division 1 · Magmatic Rocks and Structures
Group V Cenozoic Volcanic Structures Sub-group Vs Viscous Lava Structures Vs1
Vs1 Autonomous Domes
Geohazard Relations The cooled outer carapace of a dome can contribute to a buildup of pressure in the dome’s interior releasing a violent explosion when the dome front collapses, giving rise to Ps1 pyroclastic flows and surges. Repeated injections of magma beneath the dome can also cause further eruptions.
Reference Characterization Autonomous domes occur in isolation as relatively smallvolume, circular, generally convex accumulations of rhyolitic lavas erupted at low rates, resting in-situ above their source vent. Lateral flow is inhibited by the lava viscosity and quick cooling following extrusion. The dome diameters vary from a few meters to several kilometers. Heights vary from a few meters to greater than 1 km. Domes grow by repeated injections of lavas which create internal foliate structures. Their surfaces range from nearly level (Fig. Vs1-2 and 3). to irregular ridges and troughs (Fig. Vs1-4), to strongly dissected (Fig. Vs1-5). These variations may relate to eruption and cooling rates and subaerial erosion. Photogeologically some domes could be confused with non-geohazardous granitic stocks (intrusions of local extent). The stocks are generally more conical than the convex domes, and display jointing not characteristic of domes.
Cas RAF, Wright JV (1987) Volcanic successions: Modern and ancient. Allen and Unwin, London, pp 81–87, 294, 391
Select Bibliography Fink J (ed) (1987) The emplacement of silicic domes and lava flows. GSA Special Paper 212 Fink JH, Anderson SW (2000) Lava domes and coulees. In: Sigurdsson H (ed) Encyclopedia of volcanoes. Academic Press, pp 307–319 Miller CD, Mullineaux DR, Crandell DR, Bailey RC (1982) Potential hazards from future volcanic eruptions in the Long Valley-Mono Lake area, East-Central California and Southwest Nevada – A preliminary assessment. USGS Circular 877 Nakada S, Miyake Y, Sato H, Oshima O, Fujinawa A (1995) Endogenous growth of dacite dome at Unzen Volcano (Japan), 1993–1994. Geology 23(2):157–160 Rose WI (1989) Volcanic activity at Santiaguito Volcano, 1976–1984. GSA Special Paper 212, pp 17–27 Scott WE (1989) Volcanic and related hazards. In: Tilling RI (ed) Volcanic hazards. Short course in geology: Volume 1. Presented at the 28th International Geological Congress, Washington D.C., American Geophysical Union, pp 9–10
Fig. Vs1-1. Location. Geographic. 05°41' E, 23°15' N, SE Algeria Source. Girod M (1971) Le Massif Volcanique de l’Atakor (Hoggar, Sahara Algérien) Etude pétrographique, structurale et volcanique. IGN France, plate 9 (groundview), p 97, fig 40 (cross section) Comments. The figure shows a ground view and a cross section of the Upper Miocene Essa trachyte lava dome in the Atakor Highland. Interbanded flows are visible in the photo. The cross section illustrates the viscous extrusion from a central vent, and the development of the concentric structure of flow foliations moving outward both radially and tangentially as lava is repeatedly injected into the growing dome. This dome is 300 m high and has a diameter of 750 m. A deposit of precursor pyroclastics is visible at the base of the structure.
Vs1 · Autonomous Domes
Fig. Vs1-2. Location. Geographic. 02°59' E, 45°49' N, south central France Source. LAR, October 1976 Comments. This is a view of the east face of the 200 m high and 1 km diameter Grand Sarcoui trachyte dome which erupted 8 300 BP. The cave entrance near the center of the dome is an abandoned adit type quarry dating from the late 18th century. (The stone’s ease of excavation and porosity, favouring dessication, led to its use for coffins and as a local building stone.). There is evidence of a small Ms1.1 rock slide to the left of the adit entrance. Location is 7 km west of Clermont-Ferrand in the Auvergne of the Massif Central. A vertical airphoto stereogram of the dome is in Fig. Vs1-3. Figure Pf1-6 gives a description of the regional geologic context of this figure.
Fig. Vs1-3. Location. Geographic. 02°59' E, 45°49' N, south central France Vertical Airphoto/Image. Type. b/w pan, stereogram Scale. 1: 25 000 Acquisition date. Not given
Source. Personal archive Comments. The Upper Pleistocene dome marked “T2” and “4” in the center of this stereomodel is pictured and described in the ground view of Fig. Vs1-2. The bordering cones north and south are typically small parasitic scoria/ ash cones from mildly explosive conduits. This site is 3 km east of the quarry in tephra of Fig. Pf1-6.
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Fig. Vs1-4. (Caption on p. 98)
Vs1 · Autonomous Domes
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Division 1 · Magmatic Rocks and Structures ▼
Fig. Vs1-4. Location. Geographic. 67°43' W, 20°54' S, southwest Bolivia Geologic. Altiplano Vertical Airphoto/Image. Type. b/w pan airphoto Scale. 1: 40 000 Acquisition date. 3 June 1964 Source. Cordova EV (1992) La Fotografia Aerea y su Aplicacion a Estudios Geologicos y Geomorfologicos – Tomo II. Universidad Mayor de San Andres, La Paz, Bolivia, modelo estereoscopico 69 Comments. A stereomodel shows a 1 km diameter Tertiary/Quaternary autonomous viscous dome 12 km west of Julaca.
Fig. Vs1-5.
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Location. Geographic. 16°59' E, 20°59' N, northern Chad Vertical Airphoto/Image. Type. MSS7. 80 m resolution Scale. 1: 650 000 Acquisition date. 26 January 1976 Source. USGS Comments. The 20 km broad Tarso Abouki siliceous (rhyolite/trachyte) dome, 2 135 m elevation is delineated on this Landsat subscene. The dome stands in marked contrast to the Ps1.1 ignimbrite fields of the adjacent calderas. See Fig. Vc3.1-11. Location is south of Bardai, in the Cenozoic volcanic cap of the Tibesti Precambrian crustal block. Boundary faults are associated with the dome, and radial dykes also occur in the structure. Neither are image-resolved. Photogeologically volcanic domes could be confused with intrusive granitic stocks, but the latter usually display a less dense jointing system, and relief that frequently reflects associated arid climate exfoliation. Physical weathering has played its part in the dissection visible on the dome, but fluvial erosion may have been effective in earlier pluvial periods.
Vs1.1 · Domes in Cones
Vs1.1 Domes in Cones
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Vs1.1
Characterization The Dome in cones Variant, commonly called a tholoid, occurs within the craters of stratovolcanoes (Vc1), shield volcanoes (Vc2), and within caldera Variant Vc3.3. General characterization is the same as autonomous domes, Vs1. Fresh domes are among the volcanic geounits that have distinctive thermal characteristics.
Geohazard Relations Lava dome emplacement has been among the most deadly types of volcanic eruptions. “Most hazards associated with domes originate when a part of a dome front collapses giving rise to pyroclastic flows. The flows may travel tens of kilometres at very high speeds.” (Fink and Anderson 2000).
Reference Fink JH, Anderson SW (2000) Lava domes and coulees. In: Sigurdsson H (ed) Encyclopedia of volcanoes. Academic Press, pp 307–319
Select Bibliography See Geounit Vs1.
Fig. Vs1.1-1. Location. Geographic. 91°35' W, 14°30' N, western Guatemala Source. Fink J (ed). (1987) The Emplacement of Silicic Domes and Lava Flows. Geological Society of America Special Paper 212, p 24, fig 8 Comments. The map shows the areas devastated by large pyroclastic flows at Santiaguito Dome below 3 771 m Santa Maria Volcano, in 1929 and in 1973. The 1929 flow is now forested and eroded by a parallel drainage system. A ground photo of the dome is in Fig. Vs1.1-2.
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Fig. Vs1.1-2. Source. Bardintzeff J-M (1997) Les Volcans. Liber, Suisse, p 43 Comments. A ground view of a small explosion at Santiaguito Dome in western Guatemala which caused approximately 1 000 deaths in 1929. A map of the devastated areas of the 1929 and 1973 explosions is in Fig. Vs1.1-1.
Vs1.1 · Domes in Cones
Fig. Vs1.1-3. Source. Rittman A-L (1976) Les Volcans. Editions Atlas s.a.r.l. Paris, p 54 Comments. Air perspective photo shows a classic tholoid dome in the Vc1 crater of fumarolic Tarumai Volcano, 1 320 m, photo date is not given. The visible slopes are covered with Pf1 tephra. The volcano is at 141°22' E, 42°41' N on the south rim of Shikotsku Caldera near the southwest coast of Hokkaido, Japan. It has been dormant since a last minor eruption on 28 February 1981.
Fig. Vs1.1-4.
Fig. Vs1.1-5.
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Source. Bardintzeff JM (1997) Les Volcans. Liber, Suisse, p 95 Comments. A closeup view of the tholoid which rose in the crater of 1 234 m Soufrière Volcano, in May 1979 following the pyroclastic flow and surge in April, at the north end of St. Vincent Island, St. Vincent and Grenadines, Antilles.
Location. Geographic. 153°16' E, 28°24' S, eastern Highlands, Australia Vertical Airphoto/Image. Type. b/w pan airphoto Scale. reduced from 1:38 000 Acquisition date. Not given Source. Twidale CR, Foale MR (1969) Landforms Illustrated. Thomas Nelson (Australia) Ltd., p 71, ill 22
Comments. Stereomodel quadruplet in the northern Tablelands shows a 1 156 m tholoid in the inactive early Tertiary Vc2 in Mt. Warning National Park shield volcano 85 km south of Brisbane. This volcano forms the central complex of the 100 km wide Tweed Volcano.
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Fig. Vs1.1-5. (Caption on p. 101)
Vs1.1 · Domes in Cones
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Division 1 · Magmatic Rocks and Structures
Fig. Vs1.1-6. Source. USGS/Cascades Volcano Observatory, photo by Dan Dzurisin Comments. This photo taken on April 28, 2006, shows the growing dome 100 m high emerged from the crater of Mt. St. Helens (Fig. Vs1.1-7) with a collapse of part of the dome front. The dome is related to a renewed activity of the volcano in the autumn of 2004.
Fig. Vs1.1-7.
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Vertical Airphoto/Image. Type. colour infrared airphoto Scale. 1: 14 000 ± Acquisition date. Not given Source. USGS Comments. The stereomodel shows a viscous dome growing in the crater of the decapitated stratocone of Mount St. Helens, now 2 250 m elevation, in the northern Cascade Range of the western cordillera, Washington State, USA. The photo was taken about one year following the catastrophic 18 May 1980 eruption. See the dome’s height and form on 28 April 2006 in Fig. Vs1.1-6. Mt. Rainier of Fig. A2-3 is 80 km to the north. The Cascade range, within the United States, is an 1 100 km long narrow linear chain, which in plate tectonic terms, is a sliver of continental margin volcanic arc.
Vs1.1 · Domes in Cones
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Fig. Vs1.1-8. Location. Geographic. 61°10' W, 14°49' N, Martinique Island, France Geologic. Neogene volcanic belt on the east margin of the Caribbean Plate Vertical Airphoto/Image. Type. b/w pan airphoto Scale. 1: 33 000 Acquisition date. 1950
Source. IGN-Photothèque Nationale, France Comments. A photo shows the tholoid-type lava dome in the crater of Mt. Pelée at the north end of the island. On 8 May 1902 the dome exploded and collapsed and a Ps1 pyroclastic flow filled the Rivière Blanche Valley killing 29000 people in a minute.Another eruption followed on 20 May. The Pf1 area east of the crater consists of undifferentiated vent proximal deposits, probably tephra. The volcano has been K-Ar dated at Mid-Pleistocene 400 000 BP.
Vs1.2 · Flow Dome Complexes
Vs1.2 Flow-Dome Complexes
described by Miller et al. (1982) who evaluated the hazard potential of the Mono Craters complex and inferred both ashfall hazard and flowage hazard.
Characterization Reference The characterization of flow-domes complexes is essentially the same as that for the parent unit. The distinction lies in the outflow of viscous coulées which flow from the dome as relatively short lobes or accumulate as corrugated aprons around the base of the dome. Flow lobes lying on a sloping surface are the most extensive. Their morphology is related to flow viscosity and flow rate.
Geohazard Relations The geohazards of flow-dome complexes are also essentially similar to those of the parent unit Vs1. They are
Miller CD, Mullineaux DR, Crandell DR, Bailey RC (1982) Potential hazards from future volcanic eruptions in the Long Valley – Mono Lake Area, East-Central California and Southwest Nevada – A preliminary assessment. USGS Circular 877
Select Bibliography Cas RAF, Wright JV (1987) Volcanic successions: Modern and ancient. Allen and Unwin, London, pp 81–87 Fink JH, Anderson SW (2000) Lava domes and coulées. In: Sigurdsson H (ed) Encyclopedia of volcanoes. Academic Press, pp 317–319 Weaver BL (2000) The geology of Ascension Island. Proceedings of the American Academy of Arts and Sciences 60:1–80
Fig. Vs1.2-1. Source. Green J, Short NM (eds) (1971) Volcanic Landforms and Surface Features. Springer-Verlag, pl 90B Comments. An air view shows a rhyolite flow that emanated from a central dome. Big Obsidian Flow which erupted 1 300 years ago is located on a fracture bounding the south side of Newberry Caldera on the Columbia Volcanic Plateau in central Oregon. The corrugated apron pattern of the flow is particularly well expressed. Compare with the vertical airphoto of Fig. Vs1.2-3 in Kenya, and Fig. Vs1.2-5 in California’s Modoc Plateau.
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Division 1 · Magmatic Rocks and Structures
Fig. Vs1.2-2. Source. Putnam WC (1938) Geographical Review. American Geographical Society, vol 28, pp 68–82 Comments. The schematic diagram adapted from Putnam shows the outflow of a short lobe of lava from a dome onto a level surface. Vs1.1 is the dome in the crater; Vs1.2 is the flow-dome out from the crater.
Fig. Vs1.2-3.
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Vertical Airphoto/Image. Type. b/w pan Scale. Not given Acquisition date. Not given Source. Green J, Short NM eds. (1971) Volcanic Landfords and Surface Features. Springer-Verlag, pl 91A Comments. The photo shows the flow-dome complex of Pakka 20 km north of Lake Baringo in the eastern Rift Valley, Kenya. The trachyte flow emanates from a breached cone. The lobes, with concentric pressure ridges, lying on a flat surface, are short and are typically arrayed as an apron around the base of the cone. Compare with the air perspective view of Fig. Vs1.2-1 in Oregon.
Vs1.2 · Flow Dome Complexes
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Fig. Vs1.2-4. Vertical Airphoto/Image. Type. b/w pan airphoto Scale. 1: 40 000 Acquisition date. Not given Source. Ray RG (1960) Aerial Photographs in Geologic Interpretation & Mapping. USGS PP 373. p 142, fig 76
Comments. Stereomodel shows a flow-dome complex at “E” and “D” that extruded from the breached Vc1 volcano, now inactive, amid faulted NW-trending belts of Lower Triassic metamorphic rocks. Location is 131°W, 55°25' N, in densely forested land on the southeast side of Revillagigedo Island on the Behm Canal in coastal foothills at the extreme south end of the Alaska Panhandle, 60 km west of the Canadian border.
Vs1.2 · Flow Dome Complexes
Fig. Vs1.2-5. Location. Geographic. 121°30' W, 41°36' N, Northern California Geologic. Quaternary/Tertiary lavas of Modoc volcanic plateau Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 20 000 Acquisition date. 31 July 1955 Source. USGS Comments. The stereomodel shows the flow-dome complex of Glass Mountain which consists of two obsidian
flows, the younger of which runs northeast (towards upper right) from a 3 395 m summit dome. Flow structure and steep margins of flows stand out. The older flow, named Hoffman, lies to the west and supports a moderate growth of pines. Its vent, Mount Hoffman, is outside the area of the photograph. The white patches on the Hoffman flow are pumice up to 18 m thick that has filled depressions on the flow surface. A line of small domes trends 30° NW from Glass Mountain. The flows are probably less than 1 000 years old.
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Division 1 · Magmatic Rocks and Structures
Vs2 Coulées
their slow rate of movement. Also the extrusions typically produce short thick flows that seldom move as far as 5 km.
Characterization
Reference
“Coulées are extrusions of lava that have aspects of both lava domes and lava flows. They are elongated extrusions of viscous lava concentrated to one side of a vent. Ridge patterns, similar to those visible on flows of flow-dome complexes, are frequently prominent on coulée surfaces. They are said to have formed in response to compression parallel to flow during advance.” (Fink and Anderson 2000).
Geohazard Relations Coulées geohazard relations are indirect. They are in common association with other geohazard-related viscous lava structures, domes (Vs1) and flow-dome complexes (Vs1.2). The flows seldom threaten human life directly because of
Fink JH, Anderson SW (2000) Lava domes and coulees. In: Sigurdsson H (ed) Encyclopedia of volcanoes. Academic Press, pp 307–319
Select Bibliography Cas RAF, Wright JV (1987) Volcanic successions: Modern and ancient. Allen and Unwin, London, pp 81, 87 Cordova EV (1992) La Fotografia Aerea y su Aplicacion a Estudios Geologicos y Geomorfologicos. Tomo II. Universidad Mayor de San Andres, pp 493–494 de Silva SL, Francis PW (1991) Volcanoes of the Central Andes. Springer-Verlag, Berlin, p 143 Krafft M, de Larouzière FD (1999) Guide des Volcans d’Europe et des Canaries. Delachaux et Niestlé, Paris, pp 290–296 Souther JG (1992) Ornostay and Koosick centres, 182. The Late Cenozoic Mount Edziza volcanic complex, British Columbia. GSC Memoir 420, p 155
Vs2 · Coulées ▼
Fig. Vs2-2.
Location. Geographic. Eolian Island Group, south Italy Geologic. Part of Mid-Paleozoic metamorphic Calabrian Massif of the Italian toe and northeast Sicily Source. Cas RAF, Wright JV (1987) Volcanic Successions. Allen & Unwin, p 86, figs 4.27 and 4.28 Comments. The photograph shows the frontal mass of the Rocche Obsidian (volcanic glass) Holocene coulée on North Lipari Island. The graphic is a cross section through the length of the coulée, with generalised internal flow foliation.
Fig. Vs2-3.
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Fig. Vs2-1.
Location. Geographic. 119°01' W, 37°53' N, eastern California Vertical Airphoto/Image. Type. Landsat Acquisition date. 2005 Source. MDA EarthSat Comments. The image covers the 12 km long line of Late Pleistocene silicic Vs1 (obsidian) Vs2 coulees and Vs1 domes misnamed Mono Craters. The larger coulees, with cliff-like marginal slopes, are arrayed normal to the trend of the range. The ruggedness of their surfaces is due to the fact that they hardened at the surface while the still molten interior continued to flow. These structures lie within a 55 km wide large complex volcanic-filled graben, Long Valley, bounded on the west by the Sierra Nevada and on the east by the White Mountains, the westernmost ranges of the Basin and Range Province. The extrusion of these structures within the last 35 000 years, chiefly about 10 000 years ago, followed a repetitous sequence in different parts of the complex. Shallow explosion pits developed, followed by a rise of viscous lavas which formed domes inside the pits. As the lavas continued to ascend they spilled over the pit rims forming coulees. The youngest feature is only 600 years old. The Vs1 dome complex in the center stands 820 m above the surrounding plain. The main encircled area encloses Johnson, Russell, and a cluster of five other domes. Volcanic unrest continues in Long Valley, a sequence of earthquakes which began in 1978 culminated in 1980. The white areas are loose fine pumice particles blown out of the craters by a series of explosions.
Location. Geographic. 39°55' E, 09°00' N, western Ethiopia Vertical Airphoto/Image. Type. b/w pan airphoto Scale. 1: 20 000 Acquisition date. Not given Source. Green J, Short ND eds (1971) Volcanic Landforms and Surface Features. Springer-Verlag, plate 91B Comments. Photo shows a 2 km long coulee flowed from a vent down the northeast flank of Fantale Volcano of Fig. Vc3.1-7 near the eastern Rift Valley. The curved ridges reflect the main directions of movement.
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Fig. Vs2-2. (Caption on p. 113)
Vs2 · Coulées
Fig. Vs2-3. (Caption on p. 113)
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Fig. Vs2-4. (Caption on p. 118)
Vs2 · Coulées
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Fig. Vs2-4. Location. Geographic. 66°29' W, 19°51' S, southwest Bolivia Geologic. Central Andes Volcanic Zone Vertical Airphoto/Image. Type. b/w pan airphoto Scale. 1: 40 000 Acquisition date. 1 January 1961 Source. Cordova EV (1992) La Fotografia Aerea y su Aplicacion a Estudios Geologicos y Geomorfologicos – Tomo II. Universidad Mayor de San Andres, La Paz, Bolivia, modelo estereoscopico 11 Comments. A stereomodel on the Cordillera Oriental at Laguna Khasilla south of Rio Mulatos covers a 5 km long by 2 km wide viscous, relatively thick, coulée of Tertiary rhyolite with the characteristic ridge pattern.
Fig. Vs2-5. Location. Geographic. 68°09' W, 22°07' S, northern Chile Vertical Airphoto/Image. Type. TM 30 m resolution Scale. 1: 100 000 Acquisition date. Not given Source. deSilva SL, Francis PW (1991) Volcanoes of the Central Andes. SpringerVerlag, p 142, fig M4 Comments. The Landsat subscene covers the discrete Chao coulee. The flow is 15 km long by 7 km wide, occupying a saddle between two volcanoes. It is the largest of its type in the world. It has been dated in the Upper Pleistocene at less than 100 000 years old. The structure is made up of three lobes of lava, shown as I, II, and III respectively. The flow fronts are 350 to 400 m high. Characteristic features of this coulee are the prominent 30 m high flow ridges on its surface. A and PF are tephra fall precursors to lobe III. Points P and L are unidentified in the source.
Vc1 · Stratovolcanoes
Sub-group Vc Major Conical Structures Vc1 Stratovolcanoes Characterization Origin and Composition The stratovolcano is the most abundant type of volcano on the Earth’s surface. More than 1 300 have been active in the last 10 000 years. The mechanism of emplacement begins when magma, normally less dense than surrounding rock, rises buoyantly toward the surface following a line or network of lines of weakness, resulting in a pipelike vertical conduit building a symmetrical cone. “The most influential factor in shaping volcano landform is the manner in which gas exits the magma. As magma nears the surface, the attendant decrease in pressure permits exsolution of dissolved gases, which then drive the eruption vertically (the only direction in which it is free to expand).” (Simkin and Siebert 2000). Repeated eruption of primary volcanic products, tephra (Pf1) and lavas (principally andesitic X1) “complement each other in building a stable structure. Outpourings of lava mix with fragmental ejecta to construct a reinforced conical landform” (Short and Blair 1986). The layering may be seen exposed by erosion on the cone flanks. Stratovolcanoes are thus also referred to as composite volcanoes.
Morphometry Stratovolcanoes can be topographically impressive, rising steeply from about 400 m to as high as 5 km above their bases. Basal diameters can range from 1 to 60 km. Average slopes range from 15° to 30°. Ollier 1981 has written that as with other crustal loadings (glacial, sedimentary) volcanoes are subject to isostatic forces and settle under their own weight. The settlement of volcanic cones causes various deformations at the base of the structure. Suzuki (1968) found that fault type settlement tends to occur when underlying sediments are thin (6 m) is clear at the upper limit of wavewashed bare bedrock.
Fig. Br7-4.
Fig. Br7-3. Source. Bardintzeff J-M (1997) Les Volcans. Liber, Suisse, p 122 Comments. A common warning panel on Pacific Ocean coasts of bedrock plains and other Littoral System SubGroups of low-lying geounits.
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Location. Geographic. 02°00' W, 48°33' N, northeast Brittany Geologic. Peneplaned Hercynian Massif Source. Personal archive Comments. Air perspective photo is over the low rock coast of northern Brittany at the Port of St Malo and the Rance ria type estuary. The area has a general elevation of 50 m with shorelines of low scarps and beaches. The scarps mark a slight late Tertiary uplift of this part of the peneplaned Hercynian Massif of Precambrian gneisses and granites. The Gulf of St. Malo is macrotidal (to 13 m). The Port of St. Malo is prominently characterized by its four locked tidal basins, and a tidal power station located in the Rance Estuary just off the bottom edge of the photo. The 3 km long Bw4 Rochebonne Beach is on the other side of the port.
Br7 · Bedrock Plains
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Division 4 · Surficial Deposits
Sub-group Bb Residual Shorelines Bb1
Group B · Marine Littoral Systems
Geohazard Relations
Bb1 Bluffs in Unconsolidated Sediments
Bluffs are susceptible to debris mud-flows and slumps Mf3; to coastal erosion processes; to storm surge floods; to tsunami runups and to eventual sea-level rise.
Characterization
Select Bibliography
Bluffs are relatively steep, unvegetated banks up to 100 m high, generally in glacial or marine sediments. They resulted from active erosion at the base. Debris blocks are frequently at the base of the bluff. Gullies and narrow beaches Bw4 at low tide are common.
Morton RA (2003) An overview of coastal land loss: with emphasis on the Southeastern United States. USGS Open File 03-337
See note and Select bibliography concerning long term sea-level rise.
Fig. Bb1-1. Location. Geographic. Central California, USA Source. Robinson GC, Spieker AM (eds) (1978) Nature to be commanded. USGS, p 12 Comments. A photo 25 km south of San Francisco shows bluffs in alluvial and beach sediments at El Granada on Half Moon Bay. Boulders are temporarily protecting the foundation of a structure in 1973. Local bluff retreat at historic rates has probably required additional protective measures or led to the demolition of this building.
Fig. Bb1-2. Location. Geographic. 58°40' W, 48°33' N, southwest Newfoundland Source. Courtesy of Natural Resources Canada, GSC. Photo by J. Shaw Comments. The photo shows 20 m high bluffs of ice-contact glaciofluvial deposits (Paraglacial Geosystem) being eroded by wave action west of Stephenville on St. George’s Bay. A Bw4 gravel beach is in the foreground. A bright recent slump is on the left. This bayhead site is 5 km east of the low rock cliffs of the tombolos of Fig. Bw6-3.
Bb1 · Bluffs in Unconsolidated Sediments
Fig. Bb1-3. Location. Geographic. Ashkelon, Israel Source. Unattributed Comments. A photo of bluffs at the north end of the Gaza Strip in the Sharon Coastal Plain. The plain is formed by extended Fu1 alluvial fans from the hills of Samaria and Judea. The fan deposits probably overlie eustatic marine sediments. A Bw4 beach is at the foot of the bluffs. The stereo model of Fig. Ec3-7 and the satellite image of Fig. Ec2/Ec3-8 show coastal dunes which commonly occur on these bluffs along this coast.
Fig. Bb1-4. Location. Geographic. 70°45' W, 41°20' N, southern Massachusetts, USA Source. LAR, October 1980 Comments. The view shows a 5 m high bluff in the Gf4 glacial till of a lobe of continental glacial terminal moraine (Gl5) of the Illinoian (Riss) Glacial Stage, 200 000 BP, on the western shore of Martha’s Vineyard Island (see Geounit Gl5 for description of glacial moraines). Wave and tide erosion of the till remove the fine matrix fractions and leave a mass of residual boulders on the inner edge of the beach. Nearby shore dunes appear in Fig. Ec1-1.
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Division 4 · Surficial Deposits
Fig. Bb1-5. Location. Geographic. 133°02' W, 69°27' N, Northwest Territories Source. Courtesy Natural Resources Canada, GSC 1995288A Comments. An air perspective view southward in 1995 shows protection works temporarily halting coastal erosion at Tuktoyaktuk, the major port of the western Canadian Arctic, at the mouth of a drowned valley on Kugmallit Bay of the Beaufort Sea Coast, current population 900. The port has a potential enhanced utility in the event of the developmement of offshore Arctic hydrocarbon resources. Coastal recession here has already caused significant property losses.
Group B · Marine Littoral Systems
Arrows point to plastic bags containing gravel dumped on the beach in attempts to arrest shoreline retreat, 75 m in a 20 year period. Additionally, Shaw et al. (1998) p 71 state “The most exposed part of the community will eventually have to be abandoned if sea level rise continues.” The unconsolidated materials here consist of 0.6 to 2.4 m of glaciofluvial outwash gravel (Paraglacial Geosystem) forming a low scarp, overlying ice-rich sands. Elevations range from 30 to 60 m, Tuktoyaktuk Airport elevation is 4.5 m. Shoreline retreat is mainly caused by intense storms with waves from the northwest that expose the ice-bonded sands at the base of the scarp. Depth to permafrost in this region is in excess of 350 m, the active layer ranges from 60 to 100 cm.
Bb1 · Bluffs in Unconsolidated Sediments
Fig. Bb1-6. Source. Wattenmeer (1976) Karl Wachholtz Verlag, Neumünster, p 94 Comments. This low air view shows unstable bluffs in postglacial outwash materials (Paraglacial Geosystem) or Pleistocene diamicton (unsorted terrigenous deposit containing a wide range of partical sizes regardless of origin), at 08°00' E, 55°33' N,southern Denmark in Ho lagoon 10 km north of Esbjerg.
Fig. Bb1-7. Source. Muus U, Petersen M (1974) Die Küsten SchleswigHolsteins. Karl Wachholtz Verlag, Neumünster, p 81, photo 49 Comments. This air perspective view east shows bluffs with local Ms3-like slumping evident in Pleistocene unconsolidated diamicton (see Bb1-6), 10°56' E, 54°23' N near Heiligenhafen at the east end of Kiel Bay, Germany.
Ms2 debris sliding here is evidently recurring, indicated by red arrows. Old, vegetated, slid material covers part of the Bw4 beach. The plantations of trees immediately behind the slideaffected bluffs appear to be attemps to stabilize the slopes. The brown turbidity offshore appears to be related to these slope movements.
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Division 4 · Surficial Deposits
Group B · Marine Littoral Systems
Fig. Bb1-8. Location. Geographic. 118°32' W, 34°02' N, southwest California, USA Source. Shepard FP (1971) Our changing coastlines. McGrawHill, p 280, fig 10.32. Reproduced with permission of The McGraw-Hill Companies Comments. A photo taken in 1932 shows 30 m bluffs at the turnoff of West Sunset Boulevard from the Pacific Coast Highway west of Santa Monica, southern California. These bluffs were last uplifted in late Miocene, they are composed of Pleistocene Fu1 fan deposits overlying Miocene shales. The fans are alluvium swept down from the south flank of the Santa Monica Mountains approximately 5 km inland. Westward toward Malibu, the shales occur as Br6 marine terraces; morphologically the bluffs and terraces are quite similar.
The surfaces of the bluffs are now completely developed residential areas. The bluffs are fronted by Bw4 beaches from which old groins have been removed. This site is 3 km west of the earth flow of Fig. Bb1-9.
Fig. Bb1-9. Source. Shepard FP,Wanless HR (1971) Our changing coastlines. McGraw-Hill Book Co., p 281, photo 10.33. Reproduced with permission of The McGraw-Hill Companies Comments. A photo at the west end of Santa Monica just east of Temescal Canyon in southern California shows a large Mf2 earth flow that occurred in April 1958 in 30 m high bluffs of Fu1 fan deposits from the Santa Monica Mountains following a period of heavy rains. The flow, with 600 000 cubic yards of debris, buried the coastal highway and extended slightly out into the sea. In recent EO satellite imagery, the displaced mass has been removed and the beach and the highway have been restored. The only trace of this slope failure is the vegetated material in the bowl of the rupture. Extensive measures have been taken to prevent sliding in these bluffs.
“Near-horizontal drainage tunnels were driven 100 to 200 feet (30 to 60 m) into the base of the cliff and outfitted with furnaces to dry the ground, where conditions were particularly hazardous and property values high.” Sharp RP (1978) Field guide coastal Southern California, p 37, Kendall/Hunt Publishing Company. This site is 3 km east of Fig. Bb1-8 in the same materials.
Bb1 · Bluffs in Unconsolidated Sediments
Fig. Bb1-10. Location. Geographic. 01°13' W, 45°44' N, Atlantic Coast Geologic. Saintonge Arch of Charente Cretaceous carbonate plateau Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 33 000 Acquisition date. 1979 Source. IGN – Photothèque Nationale, France Comments. Shoreline bluffs in this stereomodel at La Coubre Point are the margin of a 20 km long by 5 km
broad belt of coastal dunes into which local tide and longshore drift are presently eroding as a result of sea level change. Longshore drift in this area is transporting sand southward and has resulted in a recession of 1 km of the coast in one century. The bluffs rise locally to 20 m; inland dunes are as high as 60 m. The latter date from the Flandrian Stage and rest on marine sediments of that transgression. The entire area covered by the photos, with the rectangular grid of access (and fire control) paths is part of the coniferous Foret domaniale de la Coubre.
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Bb1.1 Bluffs in Frozen Sediments Characterization This Variant of bluffs in unconsolidated materials is limited in occurrence to the circum-Arctic coastal margin dominated by cryological processes. It consists of finegrained ice-rich deposits of glacial, marine and lacustrine origin. The intersticial and massive ice in the bluffs provides transient strength to otherwise unlithified sediments allowing the development of over-steepened bluffs.
Geohazard Relations Arctic coastlines are the site of most of the human activity that occurs at high latitudes. Many settlements, airstrips, port and defence facilities are located on ice-rich terrain near sea level. Ice-rich coastal bluffs are undergoing rapid retreat by hydromechanical and thermodenudational erosional processes. Hydromechanical erosion is accomplished by waves that can attack shorelines only after they have been cleared of fast ice in the spring. Retreat of 2 to 18 m per year is accomplished entirely within an average three month openwater period. Such erosion rates are attributed primarily to the presence of ground ice in the coastal materials. The thermodenudational erosion processes acting on the ice-rich bluffs include debris slides, ground-ice slumps and thermoerosional falls:
Group B · Marine Littoral Systems
Debris sliding Ms2 occurs when the thawed surface layer fails as a result of oversteepening at the bluff base. Ground ice thaw-flow slides Zk2 result from exposure of the ice-rich soil during coastal retreat. A steep headwall retreats due to melting of the ice, and a mix of thawed sediment and water slides down the face of the headwall and flows seaward. Thermoerosional falls are block slumping mass movements Ms3. The slumped material, often bounded by ice-wedge Zi4, is removed mechanically by waves and long shore currents. Note: the thaw of frozen sediment may result in delayed but predictable subsidence, the thaw of massive ground ice in sediments may cause rapid subsidence.
Select Bibliography Algus M (1986) The development of coastal bluffs in a permafrost environment: Kivitoo Peninsula, Baffin Island. PhD thesis (unpublished), McGill University Carter LD, Heginbottom JA, Ming-ko Woo (1987) Arctic lowlands. In: Graf WL (ed) Geomorphic systems of North America. GSA, Cennial Special vol 2, pp 612–615 Dallimore SR, Wolfe S, Solomon SM (1996) Influence of ground ice and permafrost on coastal evolution, Richards Island, Beaufort Sea Coast, NWT. Canadian Journal of Earth Sciences 33:664–675 Harper JR (1978) The physical processes affecting the stability of tundra cliff coasts. PhD thesis. Louisiana State University Mackay JR (1986) Fifty years (1935 to 1985) of coastal retreat west of Tuktoyaktuk, District of Mackenzie. Current research Part A: GSC Paper 86–1A, pp 727–735
Fig. Bb1.1-1. Source. Taylor RB (1990) Geology of the continental margin of eastern Canada. In: Kean MJ, Williams GL (eds) GSC Geology of Canada, no 2, p 756, fig 14.11 Comments. These block diagrams show the various types of thermodenudational (thaw mass wasting) processes that affect bluffs in icebonded sediments.
Bb1.1 · Bluffs in Frozen Sediments Pollard W, Couture N, Strommer M, Solomon S (1999) Ground ice conditions along the Beaufort Sea coast. An International Workshop on Arctic Coastal Dynamics. GSC Open File 3929, p 21 Reimnitz E, Graves SM, Barnes PW (1985) Beaufort Sea coastal erosion, shoreline evolution, and sediment flux. USGS Open-File Rep. 85–380 Taylor RB, Mc Cann SB (1983) Coastal depositional landforms in northern Canada. In: Smith DE, Dawson AG (eds) Shorelines and isostasy. Academic Press, pp 53–75 Vasilief AA, Leibman MO (1999) Ground ice of the Baydarata Bay coast (Kara Sea) and its influence on the mechanisms of coastal destruction. An International Workshop on Arctic Coastal Dynamics, GSC Open File 3929, p 30 Wolfe S, Dallimore SR, Solomon SM (1998) Coastal permafrost investigations along a rapidly eroding shoreline, Tuktoyaktuk, NWT. Proc. 7th International Permafrost Conference, Presses de l’Université Laval, Québec, pp 1125–1131
Fig. Bb1.1-2. Location. Geographic. 137°57' W, 69°05' N, northern Yukon Territory, Canada Source. Courtesy of S. Dallimore, G.S.C Comments. A photo, taken in July 1987, shows thermoerosional block falls in bluffs of ice-bonded L1 glaciolacustrine and glacial till (Gf4) sediments. The location is on the Arctic Coastal Plain at King Point of Mackenzie Bay, 8 km west of the bluffs of Fig. Bb1.1-4.
Fig. Bb1.1-3. Source. Courtesy of Natural Resources Canada, GSC 202262E Comments. A ground level view of the Zk2 flow slide on the Yukon Coastal Plain shown in the airphotos of Fig. Bb1.1-4.
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Group B · Marine Littoral Systems
Bb1.1 · Bluffs in Frozen Sediments ▼
Fig. Bb1.1-4.
Location. Geographic. 137°54' W, 69°05' N, Yukon Territory Geologic. Paraglacial Geosystem coastal plain Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 40 000 Acquisition date. Not given Source. Courtesy of Natural Resources Canada, NAPL A 26779-10, 11 Comments. A stereomodel shows a 7 km segment of the bluff shoreline of the King Plains on Mackenzie Bay. The bluffs are 60 m high and are composed of massive ground ice and ice-bonded Mid Pleistocene lacustrine and glacial sediments. The Zk 2 300 m × 200 m retrogressive thaw flow slide of Fig. Bb1.1-3 in the center is typical of active thermokarst in these arctic coastal sediments. This particular slide is reported to be stabilized: “Icy sediments and massive ice are exposed on a steep slope in the headwall… As they melt, the sediment and meltwater flow or slide down the headwall to its base where they form a soupy mixture and flow farther downslope on gentle slopes in the form of a mudflow. Where sediment is not removed from the base of the (slide), it will stabilize at a slope between 2° and 10°.” Rampton VN (1982) Quaternary geology of the Yukon Coastal Plain. GSC Bulletin 317, pp 29–30. ▼
Fig. Bb1.1-5. This location is the same as Fig. Zk1-9 and is 8 km east of the bluffs of Fig. Bb1.1-2.
Location. Geographic. 135°26' W, 69°37' N, North West Territories Geologic. Stony clayey Early Wisconsinan (Würm) (70 ka) glacial till Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 40 000 Acquisition date. Not given Source. Courtesy of Natural Resources Canada, NAPL A 12857-408, 409 Comments. The stereomodel shows the northern end of 10 × 5 km Pelly Island off the north end of the Mackenzie Delta. The island’s shoreline is composed of ice-rich finegrained matrix of glacial till(Gf4). The indicated Bb1.1 location is a 200 m wide Mf1.2 retrogressive thaw flowslide affecting 1 900 m of shoreline in a 40 m bluff, the highest part of the island. The slide is one of 10 similar movements that occur around the shores of the island. A detached Bw5 spit beach extends 5 km eastward from the island’s north tip. Large Zk1 thermokarst lakes occupy the greater part of this island. Pelly Island is 125 km northeast of the bluffs of the Yukon Plain in Fig. Bb1.1-4. Dark patches in the sea are cloud shadows.
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Fig. Bb1.1-5. (Caption on p. 707)
Group B · Marine Littoral Systems
Bw2 · Offshore Bars
Sub-group Bw Wave and Current-formed Littoral Sediments
are potentially hazardous to surface navigation and marine engineering activities if uncharted or mispositioned.
Bw2 Offshore Bars
Select Bibliography
Characterization Offshore bars are subtidal ridges of sand that parallel the shoreline and are continuously submerged even at low tide. They can occur singly or as multiple ridges. In eastern Canada the bars are typically located from 150 to 300 m offshore as a function of the bottom gradients, and their crests are from 1 to 4 m below mean water level. They can be continuous for distances of several kilometers, or be discontinuous and irregular in shape. The bars are produced by strong storm waves that rework the seabed sands. The location of the ridges can be detected directly on airphotos and some satellite images or by breaking wave patterns parallel to the shore. Such patterns are more prominent if the photos or images were acquired under relatively high energy conditions.
Alexander PS, Holman RA (2004) Quantification of nearshore morphology based on video imaging. Marine Geology 208(1):101–111 Bascom W (1980) Waves and beaches. Anchor Press/Doubleday, Garden City, New York, pp 262–265 Davidson-Arnott R (1990) Sandy beaches and nearshore bars. In: Keen MJ, Williams GL (eds) Geology of the continental margin of eastern Canada. GSC, Geology of Canada 2:642–645 Davis RA, Fox WT (1972) Coastal processes and nearshore sand bars. Journal of Sedimentary Petrology 42:401–412 Greenwood B, Davidson-Arnott RGD (1979) A tentative classification of bars. Canadian Journal of Earth Science, pp 312–332
Geohazard Relations Fig. Bw2-1. Offshore bars are subject to erosion by storm wave activity and storm surges which remobilize and redistribute the bar sediment. As submerged bottom features in areas normally dominated by dynamic marine conditions, they
Source. Bird ECF (1976) Coasts. Australian National University Press, p 1, fig 2 Comments. A schematic section shows the location of an offshore bar in relation to other units of a depositional coast.
Fig. Bw2-2. Source. Wattenmeer (1976) Karl Wachholtz Verlag, Neumünster, p 76, ill 95 Comments. This is a view northeastward at Trischen Island in Wadden See National Park, 20 km north of Cuxhaven, Schleswig Holstein, Germany, 08°41' E, 54°03' N. A sequence of four marine littoral geounits is displayed from west to east in this air perspective view: the Bw2 offshore bar, located by the breaking line of surf the smooth Bw4 beach the bright Ec2 transgressive dunes, 3 m in height the drained and undrained protected Bt1 lagoon deposits The island has migrated significantly. It is now 10 km east of its position 400 yr ago. It has also lost a quarter of its former size in 80 yr, its current area is 180 ha. See also Fig. Ec3-5.
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Group B · Marine Littoral Systems
Fig. Bw2-3. Location. Geographic. Unspecified Geologic. Marine littoral systems Source. Davis RA (1985) In: Davis RA (ed) Coastal Sedimentary Environments, 2nd edn. Springer Verlag, p 390, fig 6-9 B
Comments. The air perspective view shows two offshore bars of a probable Bw3 barrier island located by the associated breaking wave patterns parallel to the shore on the USA southeast coast.
Fig. Bw2-4. Location. Geographic. 61°35' W, 47°36' N, Magdalen Islands, Québec Source. Owens EH, McCann SB (1980) The coastal geomorphology of the Magdalen Islands, Quebec. In: McCann SB (ed) The coastline of Canada. GSC Paper 80-10, p 63, fig 5.17
Comments. The air perspective photo shows the breaking wave pattern marking the position of offshore bars as in Fig. Bw2-3 parallel to the spilling breakers (see Bw4) of the Bw6 Dune du Nord Tombolo Beach.
Bw2 · Offshore Bars
Fig. Bw2-5. Location. Geographic. 75°31' W, 35°14' N, North Carolina Vertical Airphoto/Image. Type. b/w pan airphoto Scale. 1: 25 000 Acquisition date. 1958 Source. Shepard FP, Wanless HR (1971) Our changing Coastlines. McGraw-Hill, p 24, fig 2.23a. Reproduced with permission of The McGraw-Hill Companies Comments. Photo shows the linear pattern of breaking waves that locate the position of a submerged offshore bar paralleling the Cape Hatteras National Seashore of the Atlantic Coastal Plain.
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Bw3 Near-Shore Barrier Beaches Characterization A barrier beach is a sand bar parallel to the shore, not attached at either end, which has been built by upward shoaling wave action so that its crest rises above the normal highwater level. The barrier’s depositional environment includes the lagoon Bt1 which it encloses and protects. Another depositional environment of barrier beaches are the tidal delta channels which cut through the barrier and connect the lagoon to the open seas, see the block diagram of Fig. Bt1-1. Barrier beaches are ubiquitous along the gently sloping coastal plains Bc1 around the world. Carter et al. (1987) state that such barriers be divided into sand and gravel barriers. Sand barriers are widespread around the world’s coastlines; gravel barriers are restricted to high latitudes on glacial and paraglacial coasts (see Paraglacial Geosystems).
Geohazard Relations Barrier beaches can be mapped “in terms of risk zones defined on the basis of property damage vulnerability as derived from the known impact of coastal processes, protective vegetative cover, and the role of protective landforms.” (Bush et al. 1996). An example of this are coastal dunes Ec. The low height and narrow width of barrier beaches makes them particularly susceptible to sea-level rise. They would be subject to overwashing and the formation of new inlets during storms. Human impacts are also geohazard agents of coastal barrier beaches. There is no greater threat to them than extensive urbanization. As people develop the shore, the normal processes of island migration become problems of erosion. Many engineering solutions have been sought, seawalls, groins, jetties; but in the long run, coastal barriers respond only to the passage of time. They are dynamic features, always moving (Wells and Peterson 1986). Longshore currents play an important part in the dispersal of sewage effluent discharge into the sea. Beaches down-drift of the sewage discharge points may suffer pollution for this reason (King 1974). See notes concerning coastal erosion, tsunami runups, and long-term sea-level rise following Geounit Bp1, Carbonate platforms.
Group B · Marine Littoral Systems
Reference Bush DM, Neal WJ, Pilkey OH (1996) A rapid barrier island hazard mapping technique as a basis for property damage risk assessment and mitigation. Proceedings of Conference on Natural Disaster Reduction, ASCE, pp 185–186 Carter RWG, Forbes JD, Taylor RB (1987) Gravel barriers, headlands and lagoons: An evolutionary model. ASCE, Coastal Sediments ’87, vol 2 King CAM (1974) Geomorphology in environmental management. Oxford Press, London, p 197 Wells JT, Peterson CH (1986) Restless ribbons of sand, Atlantic & Gulf Coastal Barriers. Institute of Marine Sciences, University of North Carolina at Chapel Hill, Morehead City, NC
Select Bibliography Andrew J, Cooper G, Pilkey OH (2002) The Barrier Islands of Southern Mozambique. Journal of Coastal Research, Spec. Iss. 36:164–172 Glaeser JD (1978) Global distribution of barrier islands in terms of tectonic setting. Journal of Geology 86:283–297 Hayes MO (1979) Barrier island morphology as a function of tidal and wave regime. In: Leatherman SP (ed) Barrier islands. Academic Press, pp 1–29 Hoyt JH (1967) Barrier island formation. GSA Bull 78:1123–1136 McBride RA, Byrnes MR (1993) Geomorphic response types along barrier coastlines: A regional perspective. Large Scale Coastal Behaviour ’93. USGS Open File Report 93–381, pp 119–122 Reinson GE (1980) Variations in tidal-inlet morphology and stability, northeast New Brunswick. The Coastline of Canada. GSC Paper 80–10, pp 23–39 Riggs SR, Cleary WJ (1993) Influence of inherited geologic framework upon barrier island morphology and shoreface dynamics. Large Scale Coastal Behaviour ’93. USGS Open File Report 93–381, pp 173–176 Schwartz ML (ed) (1973) Barrier islands. Dowden, Hutchinson and Ross, Stroudsburg Shepard FP, Wanless HR (1971) Our changing coastlines. McGrawHill, New York, pp 71–161
See also Select Bibliography for Marine Littoral Geounit Sub-groups following Geounit Bp1, Carbonate platforms.
Fig. Bw3-1.
▼
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Source. Reinson GE (1980) The coastline of Canada. GSC Paper 80-10, fig 3.14, p 33 Comments. This map shows the characteristic depositional environment of barrier beaches – the beach itself in 1945; the enclosed Bt1 lagoon; and the tidal inlet breach area Bt1a existing in 1977. In the example, at Tabusintac on the northeast New Brunswick Coast, the barrier is migrating southward by strong longshore drift in response to short-period windgenerated storm waves from the northeast. This site is 22 km south of Fig. Bt1-2 at Tracadie.
Bw3 · Near Shore Barrier Beaches
▼
Fig. Bw3-2.
Vertical Airphoto/Image. Type. b/w pan airphoto Scale. 1: 40 000 Acquisition date. Not given Source. IGN – Photothéque Nationale, France Comments. The photo is at the beach town of Palavas, 03°56' E, 43°32' N, in the photo center, 10 km south of Montpellier, covers 9 km of an extensive system of barrier beaches that line the Mediterranean coast of France from the Rhone Delta to the Pyrenees. The shallow brackish lagoons in the photo, Méjean and Arnel, are near-stagnant; streams that could disharge fresh water into them are seen to be channeled through them direct to the sea. Another water system that traverses the lagoons but is isolated from them by dykes, is the channel of a barge canal that links the navigation of the lower Rhone River 60 km to the northeast with the industrial port of Sète 16 km to the southwest. ▼
Fig. Bw3-3.
Location. Geographic. 82°40' W, 27°50' N, west central Florida Vertical Airphoto/Image. Type. TM 30 m resolution Scale. 1: 160 000 Acquisition date. Not given Source. USGS Comments. Large scale Landsat subscene covers the low, (1:5 000 to be resolved and mapped.
Forbes DL, Taylor RB (1994) Ice in the shore zone and the geomorphology of cold coasts. Progress in Physical Geography 18(1):59–89
Select Bibliography Harper JR (1985) Ice interaction with coastal processes. Short course lecture notes, coastal processes and engineering. Associate Committee for Research on Shoreline Erosion and Sedimentation, NRC, pp 91–114 Lauriol B, Gray JT (1980) Processes responsible for the concentration of boulders in the intertidal zone in Leaf Basin, Ungava. The coastline of Canada. GSC Paper 80–10, pp 281–292 McLaren P (1980) The coastal morphology and sedimentology of Labrador: A study of shoreline sensitivity to a potential oil spill. GSC Paper 79–28 Ogorodov SA (2003) The role of sea ice in the coastal zone dynamics of the arctic seas. Water Res. MAIK Nauka/Springer 30(5):509–518
Geohazard Relations Boulder barricades and ice-thrust ridges are impediments for landing operations in the nearshore zone, and ice rideups onshore are destructive of transport facilities and installations for resource development in high latitudes. Boulder barricades. Shores with boulder barricades are difficult to approach from the sea, they offer restrictions to boat travel, some can only be crossed at high tide. In oil spill events boulder barricade zones would be difficult to clean. Ice ride-ups and pile-ups. Sea ice is a major seasonal hazard to structures in the Arctic and also in more southern latitudes. During spring breakup ice floes composed of blocks 1 to 2 m thick are driven onshore by wind and waves and can pile up into ridges by buckling up to 30 m high. They override beaches and hit fixed objects with considerable force. Artificial islands used for oil and gas
Fig. Bl1-1. Location. Geographic. Northwestern Canadian Arctic Archipelago, Queen Elizabeth Islands Geologic. Cretaceous sediments of Sverdrup Basin of Queen Elizabeth Islands Sub-plate Source. Amos CL (1990) Geology of the continental margin of Eastern Canada. GSC Geology of Canada, no 2, fig 11.19B, p 640 Comments. Map shows coastal types in a region where shores are ice-locked for at least 11 months each year and dominated by the actions of sea ice and absence of wave action. The delineated ice push/override shore segments consist of ice ride-ups and pile-ups. The scarred shorelines are marked by boulder barricades and ice-rafted boulders.
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Division 4 · Surficial Deposits
Group B · Marine Littoral Systems
Fig. Bl1-2. Location. Geographic. 88°11' W, 80°26' N, Axel Heiberg Island, Nunavut Geologic. Triassic sediments of Sverdrup Basin of Innuitian Orogen Source. Bird JB (1967) The physiography of Arctic Canada, with special reference to the area south of Perry Channel.
Pl 40, © Johns Hopkins Press. Reprinted with permission of The Johns Hopkins University Press Comments. Ground view shows typical ice thrust ridges on the shores of the Schei Peninsula at the junction of Nansen and Eureka Sounds. In the northeast part of the island. Rucksack gives scale.
Fig. Bl1-3.
Comments. The arrows in this photo point to a boulder barricade concentrated at the low tide line on a narrow tidal flat on the eastern Shield coast of central Labrador at 58°55' W,54°55' N.
Source. Courtesy of Natural Resources Canada, GSC 203475W
Bl1 · Sea Ice Forms
Fig. Bl1-4. side of Pangnirtung Fjord, derived from Gf4 glacial till further up the fjord. The barricade is deposited on an intertidal flat at the south end of Auyuittuq National Park on Cumberland Peninsula. See the stereomodel of this site on Fig. Bl1–5.
Fig. Bl1-5.
▼
Location. Geographic. 65°50' W, 66°07' N, eastern Baffin Island, Nunavut Source. Courtesy of Natural Resources Canada, GSC. Photo by A. S. Dyke Comments. The arrows in this photo point to a 1 to 2 m high sea ice formed boulder barricade on the western
Location. Geographic. 65°50' W, 66°07' N, eastern Baffin Island, Nunavut Geologic. Eocene horst of the northeast shield Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 3 180 Acquisition date. 1 August 1980 Source. Courtesy of Natural Resources Canada, NAPL A 25553-93, 94 Comments. These very large scale photos at the site of Fig. Bl1-4 show a boulder barricade marked by arrows. The segment pictured in the photo is 950 m long and 50 m wide. The intertidal flat between the barricade and the shoreline marked Bt2.2 varies from 175 m to 275 m wide; its surface is strewn with lag boulders rolled in by ice flows.
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Fig. Bl1-5. (Caption on p. 743)
Group B · Marine Littoral Systems
Bt1 · Lagoons
Sub-group Bt Tidal Regime Deposits and Forms Bt1 Lagoons Characterization Lagoons are sedimentary complexes that include barrier beaches Bw3. Typically, they occur where a low-gradient continental shelf is adjacent to a low-relief coastal plain Bc1. “Lagoons form where coastal embayments or depressions are separated from the adjacent sea by a barrier. Barriers comprise either clastic material (e.g., Bw3) or are created by vegetation, coral growth or tectonics.” (Cooper 1994). The evolutionary processes of lagoons overlap between estuaries Fw3 and tidal flats. Enclosure of a lagoon is accomplished by elongation of a spit Bw5, or by shoreward migration of a barrier ridge that originated offshore. Lagoon water occurs in three zones: a fresh-water zone from streams on the landward side; a salt water zone close to the inlets; and a transition brackish water zone. Within the lagoon water body a number of Component depositional geounits may occur: Component a. Tidal deltas – are sand bodies deposited from bi-directional flow located at inlet breaches in barrier beaches Bw3. “The ebb-tidal delta is a sand accumulation seaward of the inlet throat, formed primarily by ebb-tidal currents but modified by wave action. The flood-tidal delta is an accumulation of sand landward of the inlet throat, shaped chiefly by flood-tidal currents.” (Boothroyd 1985). Both types consist of channel and shoal systems in form. Component b. Washover fans – are created by wind-generated storm surges that overtop barrier beaches and deposit sand in the lagoon in relatively thin sheets, a few centimeters to two meters during each wash event, and a few hundred meters in width. “If the washover flow is unconfined, then the land surface is inundated by sheetwash. However, if the washover flow is confined to interdune lows or incised channels, then the energy of onshore flow is concentrated, flow velocities accelerate, and washover sediments are transported and deposited much farther inland.” (Morton 2002). Component c. Salt marshes and mangrove swamps – As with coral reefs, salt marshes exhibit a remarkable interplay between geological, hydrological, biological and chemical processes. Photographically and spectrally, the prime indicator of this component is the community of halophytic plants (strong near-infrared reflectance). This is a flora of reed type rushes and cord grasses.
As described in Fig. Bt1c-3, in low latitudes mangrove tree communities replace the marsh plants. These forests occur in similar situations along the coasts of many tropical coastal regions. They are readily identified by most sensor systems, including low resolution MSS Landsat images, particularly colour infrared wavelengths, in common with other biomasses. Swamp woodlands are associated wetlands. The marshes occur as low marshes corresponding to the upper intertidal zone with a muddy substrate, and high marshes which are supratidal and are more influenced by terrestrial conditions, with more permeable sands substrate. Both types are drained by a typical pattern of intricately meandering creeks. Sediment carried into a marsh by the rising tide, is trapped by the vegetation and retained as the tide ebbs. The marsh level is thus gradually built up. Salt marshes and mangrove swamps have been a striking instance of humankind acting as a geohazard agent in its own right. They have historically been greatly reduced in extent by draining for land development or transformed into garbage-based dry land. Mangrove forests are depleted for fuel wood and conversion into shrimp ponds. Mangroves can provide a buffer to storm surges and tsunami runups, while loosing some trees they can absorb most of the energy from the waves. Component e. Sabkhas – These deposits occur in subaerial or arid coastal environments just above normal high tide level where evaporation rates are high. They consist of silt, clay and muddy sand in shallow depressions. The deposits are commonly saturated with brine and are often salt encrusted. Salt crusts are spectrally revealed by their brightness on airphotos and images, similar to L2 inland playa surfaces. Component g. Polders – consist of zones in lagoons that have been dyked, drained by artificial means, and kept dry by pumping. The fertile lands are usually intensely developed for agriculture, and large ones are frequently under severe population pressure. Polders are readily visible on all types of airphotos and images by their geometric patterns which contrast strongly with the surrounding natural lagoon components.
Geohazard Relations As in the cases of littoral sediment and coastal plain geounits, lagoons are susceptible to storm surges, tsunami runups and long-term sea-level rise. “Under normal dry conditions the sabkha provides an excellent running surface for wheeled vehicles but under high water table conditions vehicles can break through the surface crust and find themselves up to the axles in a liquid mud.” (Ellis 1973).
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References Boothroyd JC (1985) Tidal inlets and tidal deltas. In: Davis RA Jr (ed) Coastal sedimentary environments, 2nd edn. Springer-Verlag, New York, p 448 Cooper JAG (1994) Coastal evolution. Cambridge University Press, Cambridge, p 221 Ellis CI (1973) Arabian salt-bearing soil (Sabkha) as an engineering material. Transport and Road Research Lab. , Report LR 523 Morton RA (2002) Factors controlling storm impacts on coastal barriers and beaches – A preliminary basis for near real-time forecasting. Journal of Coastal Research 18(3):486–501
Select Bibliography Althausen JD, Clark JS, Conroy CM (1995) Image processing techniques used in studying satellite images of the Arabian Gulf: Kuwait, Saudi Arabia, and the United Arab Emirates. Society of Economic Mineralogists and Paleontologists Congress Barth H-J, Boer B (2002) Sabkha ecosystems. Springer-Verlag Bubshait AA (2001) Quality of pavement construction in Saudi Arabia. Practice periodical on structural design and construction, Aug, pp 129–133
Group B · Marine Littoral Systems Bird ECF (1976) Coasts. Australian National University Press, pp 190–204 Commission on Mitigating Shore Erosion along Sheltered Coasts (2007) Ocean Studies Board, NRC (USA) Cooper JAG (1994) Lagoons and microtidal coasts. In: Carter RWG, Woodroffe CD (eds) Coastal evolution. Cambridge University Press, Cambridge, pp 219–266 Davies JL (1977) Geographical variation in coastal development. Longman, London, pp 162–180 Frey RW, Basan PB (1985) Coastal salt marshes. In: Davis RA (ed) Coastal sedimentary environments, 2nd edn. Springer-Verlag, New York, pp 225–301 Hayes MO (1980) General morphology and sediment patterns in tidal inlets. Sedimentary Geology 26:139–156 Reineck H-E, Singh IB (1973) Depositional sedimentary environments. Springer-Verlag, New York, pp 150–154 Reinson GE (1980) Barrier island systems. Facies models. GSA, Geoscience Canada, Reprint Series 1, pp 57–74
See Select bibliography for Marine Littoral Geounit Subgroups. See Note concerning long-term sea-level rise. See Note concerning tsunami runups following Geounit Bp1, Carbonate platforms.
Fig. Bt1-1. Source. Reinson GE (1980) Barrier island systems. In: Walker RG (ed) Facies models. Geological Association of Canada, p 58, fig 2 Comments. This modified block diagram locates the morphosedimentary Components of lagoons and the Geounits commonly associated with them.
Fig. Bt1-2.
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746
Location. Geographic. 64°53' W, 47°32' N, Acadian Peninsula, New Brunswick Geologic. Central platform of Acadian Appalachian Orogen Vertical Airphoto/Image. Type. b/w pan, airphoto Scale. 1: 43 000 Acquisition date. Not given Source. Courtesy of Natural Resources Canada, NAPL A 13143-57, 58 Comments. Stereomodel shows some morphosedimentary lagoon Components and units in a Bc3 glaciomarine plain at Tracadie: Bw3 is the barrier beach that encloses the lagoon; a are tidal deltas; c are salt marshes. This site is 22 km north of Fig. Bw3-1 at Tabusintac.
Bt1 · Lagoons
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Division 4 · Surficial Deposits
Fig. Bt1-3.
▼
Location. Geographic. 95°14' E, 05°29' N, Banda Aceh, north Sumatra, Indonesia Geologic. Bc1 coastal plain Source. Satellite image courtesy of Geo Eye Comments. A pair of images shows the before and after states of the tsunami runup of the Sumatra-Andaman earthquake at Longha Lagoon on the open coast west of Banda Aceh City on 10 January 2003 and 29 December 2004. 130 000 lives of the total 230 000 were lost in this region.
Fig. Bt1-4.
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748
Location. Geographic. 07°02' E, 53°21' N, north Germany Source. LAR, 1977 Comments. This panel plan describes the filling of a lagoon-like dyked area with sand dredged from a shipping channel. The location is 10 km seaward of the port of Emden on the Ems River Estuary in East Friesland. Strong tidal movements constantly silt up the estuary, and navigation to the port by large ore-carrying vessels requires constant dredging.
Group B · Marine Littoral Systems
Bt1 · Lagoons
Fig. Bt1b-1. Source. Reineck H-E, Singh IB (1973) Depositional sedimentary environments. Springer-Verlag, p 298, fig 434 Comments. The air perspective photo shows washover fan sediments deposited onto the salt marsh area of a lagoon on the southeast coast of the United States. The Bw4 lagoon barrier beach is in the lower part of the photo. “One of the major agents modifying estuaries and lagoons (including the barriers to which the lagoons owe
their existence) is the hurricane.” (Authors’ storm surge geohazard). “It is probable that all of the province's lagoons have been affected by hurricanes at some time or other. Along some sections, especially the Gulf Coast and southern Atlantic Coast, they are of major importance.” (Walker HJ, Coleman JM (1987) Atlantic and Gulf Coastal Province In: Graf WL (ed) Geomorphic systems of North America. Geological Society of America, Centennial Special vol 2, p 94).
Fig. Bt1b-2. Source. Morton RA (2002) Factors controlling storm impacts on coastal barriers and beaches – A preliminary basis for near real-time forecasting. Journal of Coastal Research 18(3), p 496, fig 12
Comments. Washover deposits constructed by a 5.5 m storm surge near Cozumel Island on the east coast of Yucatan Peninsula, Mexico.
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Division 4 · Surficial Deposits
Group B · Marine Littoral Systems
Fig. Bt1b-3. Location. Geographic. 61° 58' W,47° 17' N, Magdalen Islands, Québec Source. Owens EH, McCann SB (1980) The coastal geomorphology of the Magdalen Islands, Quebec. In: McCann SB (ed) The coastline of Canada. GSC Paper 80-10, p 59, fig 5.11 Comments. An air perspective photo shows a washover fan that has reached 600 m into Havre aux Basques Lagoon on the west side of Ile du Havre-Aubert.
Fig. Bt1b-4. Location. Geographic. Maine, USA Geologic. Structurally controlled lowland of Acadian tectogenic belt Source. Morton RA (2002) Factors controlling storm impacts on coastal barriers and beaches – A preliminary basis for near real-time forecasting. Journal of Coastal Research 18(3), p 491, fig 6 Comments. In this photo a gravelly washover fan deposit constructed by waves of a 1 m storm surge lies just below the house balcony near Portland.
Fig. Bt1b-5.
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750
Location. Geographic. 97°11' W, 27º39' N, Northwest Gulf of Mexico, Texas Geologic. Bc1 coastal plain of Marine Quaternary sediments Vertical Airphoto/Image. Type. Pan, b/w airphoto Scale. Not indicated Acquisition date. Photo A: 1967; photo B: 1969
Source. Unspecified U.S. government agency Comments. The photo pair covers a short segment of Mustang Island Bw3 barrier beach that encloses Laguna Madre of Corpus Christi Bay. Photo A was taken immediately following a hurricane. It shows storm surge related breaching of the barrier and deposition of washover fan components in the lagoon. Photo B was taken 2 years later. The extent of the barrier recovery and persistence of the lagoon fans are evident.
Bt1 · Lagoons
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Division 4 · Surficial Deposits
Group B · Marine Littoral Systems
Fig. Bt1b-6. Vertical Airphoto/Image. Type. b/w pan Scale. (see bar) Acquisition date. Not given Source. Morton RA (2002) Factors controlling storm impacts on coastal barriers and beaches – A preliminary basis for near real-time forecasting. Journal of Coastal Research 18(3), p 491, fig 5 Comments. A vertical airphoto shows a 700 m wide × 700 m length washover fan on the lagoon behind the low-lying Bw3 barrier beach of Cedar Island Virginia, USA. The fan was deposited in 1962 by a 2.5 m storm surge.
Fig. Bt1b-7.
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752
Location. Geographic. 69°56' W, 41°42' N, eastern Massachusetts Geologic. Bw3 barrier beach of a sub-lobe of Wisconsinan/ Würm continental ice Vertical Airphoto/Image. Type. b/w pan, airphoto Scale. 1: 12 000 Acquisition date. April 1961 Source. Shepard FP, Wanless HR (1971) Our changing coastlines. McGraw-Hill, p 23, fig 2.21. Reproduced with permission of The McGraw-Hill Companies Comments. The photo fragment illustrates two generations of washover fans across Nauset Beach barrier near Chatham at the southeast tip of Cape Cod. The larger older fan, 1 400 m long by 650 m across, is in an eroded degraded-appearing condition. It is bounded on the lagoon side by a narrow barrier developed by tidal currents flowing through the locally narrow Chatham Harbour pass. The more recent, smaller washover to the north is 600 m wide by 400 m across. The washover form is similar to that of a Bt1a flood tidal delta, but lacks the breach channel through which delta flows pass. The old fan is now largely infilled and some hutments have been constructed on the bay side. The small fan has been eroded away.
Bt1 · Lagoons
753
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Division 4 · Surficial Deposits
Group B · Marine Littoral Systems
Fig. Bt1c-1. Source. Reineck H-E, Singh IB (1973) Depositional sedimentary environments. Springer-Verlag, p 361, fig 518 Comments. The photo shows the bedding of fine-grained sediments with some bedding planes of shells that are normally accreted in a supratidal salt marsh.
Fig. Bt1c-2. Location. Geographic. 69°57'38'' W, 41°49'55'' N, Massachusetts, USA Source. LAR, 1975 Comments. A meadow of short, 20 to 30 cm Spartina patens salt hay on a tidal creek in Nauset Bay on the east coast of Cape Cod. This is one of the characteristic marsh halophyte grasses. The enclosing Bw3.1 Nauset barrier beach is in the background. Spartina alterniflora cordgrass appears as a fringe at the water’s edge. Spartina patens characteristically falls over when it ages, forming a mat through which next year’s growth emerges. It grows best on mud and sand flats where the seawater is diluted by rains or by freshwater coming into the saltwater at the mouth of a stream.
Bt1 · Lagoons
Fig. Bt1c-3. Location. Geographic. 167°30' E, 16°30' S, Vanuatu Source. Vocabulaire géographique, Tome 1 (1966) Masson et cie éditeurs, photo by Aubert de la Rüe Comments. This is a close ground view of the margin of a mangrove plant community on Malekula Island. Mangroves are tropical and subtropical shrubs and trees that grow in saline and brackish wetlands. They are homologous to higher latitude salt marsh ecosystems, but there are many shores in the tropics on which salt marsh and mangrove occur side by side. Mangroves range from pioneering low scrub on the seaward side to tall forest inland. They average from 6 to 12 m high, and in exceptional cases can be over 30 m tall. The photo shows the characteristic air absorbing root system which anchors the plant in the soft and shifting muddy substrate and promotes stabilization and accre-
Fig. Bt1c-4. Location. Geographic. 128°05' E, 15°25' S, northwest Australia Source. Kulmar S (1982) In: Kennedy T (ed) Australia’s beautiful coastline. Australia. Consolidated Press Ltd., pp 57–58 Comments. This air perspective view shows a mangrove community in the tidal reach of Wyndham River. A ground view and description are in Fig. Bt1c-3.
tion of sediment. Mangroves offer some protection against coast erosion and storm surge attack. In common with many types of wetland, mangroves are subject to man-induced disturbances and depletion; e.g., use for lumber; aquaculture development (shrimp farming in Thailand). See also Fig. Bt1c-4.
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Division 4 · Surficial Deposits
Group B · Marine Littoral Systems
Fig. Bt1c-5. Location. Geographic. 81°17' W, 31°28' N, southeast coast, USA Vertical Airphoto/Image. Type. Colour infrared, airphoto Scale. 1: 6 400 Acquisition date. 14 September 1971 Source. Reimold RJ, Gallagher JL, Thompson DE (1973) Remote sensing of tidal marsh. Photogrammetric Engi-
neering 39(5), p 483, pl 1, American Society of Photogrammetry Comments. Large-scale photo shows an area of salt marsh inside of Sapelo barrier island along the coast of Georgia. The blue-red colour of the marsh reflects the dominant presence of the tall Spartina alterniflora cordgrass of Fig. Bt1c-2. The bright red areas are trees on dry land.
Bt1 · Lagoons
Fig. Bt1c-6. Vertical Airphoto/Image. Type. b/w pan, stereogram Scale. 1: 46 000 Acquisition date. February 1940 Source. Personal archive Comments. Stereomodel shows a typical occurrence of a lagoonal salt marsh (T descriptor) near latitude 39°50' N in Ocean County, New Jersey, USA. C and L indicate the Bc1 coastal plain, S is a disused flooded sand pit.
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Division 4 · Surficial Deposits
Fig. Bt1c-7. (Caption on p. 760)
Group B · Marine Littoral Systems
Bt1 · Lagoons
Fig. Bt1c-8. (Caption on p. 760)
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Division 4 · Surficial Deposits
Group B · Marine Littoral Systems
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Fig. Bt1c-7. Location. Geographic. 77°56' W, 18°28' N, northwest Jamaica Geologic. Paleogene marine limestones of the Nicaraguan Rise of Caribbean Plate Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 24 000 Acquisition date. Not given Source. Personal archive Comments. The stereomodel at Montego Bay shows a 2.5 km long zone of intertidal flat at the head of coralprotected Bogue Lagoon. The flat is occupied by mangrove swamp as in Figs. Bt1c-3 and Bt1c-4. The adjacent Bc1 coastal plain and terraces are densely cultivated with tropical crops such as bananas, sugar cane, or pineapple. The enclosing coral peninsulas were in the process of being developed when the photos were taken. The 300 m zone between the mangroves and the N/S road is now developed for aquaculture.
▼
Fig. Bt1c-8.
Location. Geographic. 09° 01' W, 05° 00' N, southern Liberia Geologic. Coastal plain of west African Shield Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 20 000 Acquisition date. 1964 Source. Personal archive Comments. The stereomodel shows the mangrove-filled intertidal flat at the mouth of the Sinoe River at Greenville 3.5 km east of the barrier beach of Fig. Bw3.1-4. The town itself is sited on raised beach ridges. It is not a fishing port and is likely a residential center for outlying cocoa and palm production activities.
Fig. Bt1c-9.
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760
Location. Geographic. 02°49' E, 42°41' N scene center, Languedoc southern France Vertical Airphoto/Image. Type. MSS resampled to 50 m resolution Scale. 1: 500 000 Acquisition date. 13 October 1981 Source. USGS Comments. The inset frame on this Landsat subscene, which is a continuation southward of Fig. Bc4-3, locates the coverage of the stereo airphotos of Fig. Bt1g-3 with the red zone showing polders and salt marshes described in that figure. The image shows the location at the north end of the 30 km × 30 km plain of Perpignan near the Spanish border. The plain is Bc4 fluviomarine consisting of Pleistocene and Holocene terrestrial and interglacial marine sediments. The surrounding highlands are igneous and metamorphic rocks of the Pyrenees and Pre-Pyrenees, with Cretaceous folded sedimentary rocks to the north (Corbières).
Bt1 · Lagoons
761
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Division 4 · Surficial Deposits
Group B · Marine Littoral Systems
Fig. Bt1e-1. Source. Personal archive Comments. A schematic profile locates the topographic site of a sabkha geounit in a desert coastal zone. Scale is approx. 1:250 000. Bubshait (2001) describes Arabian Peninsula sabkhas as being made up of nonuniform, variable, and highly compressible materials which lead to differential settlement of road pavements. Pavement cracking results from
salt crystallization near the surface and volume change of gypsum due to hydration and dehydration. Construction methods include 1 m high embankments and stabilization of the sabkha with asphalt admixtures. Also the high concentration of chlorides and sulfates in sabkha sediments makes it highly corrosive. Mobile sand encroachment as illustrated in Figs. Ef1-1 and Ef1-2 also occurs.
Fig. Bt1e-2. Location. Geographic. 54°20' E, 24°10' N, United Arab Emirates Source. Ellis CI (1973) Arabian saltbearing soil (sabkha) as an engineering material. Overseas Unit Transport and Road Research Laboratory, Crowthorne, Berkshire, Department of the Environment TRRL Report LR 523, pl 2 Comments. This view shows typical local trafficability along the Persian Gulf coasts of Abu Dhabi and Dubai. The bluffs in the background are interbedded, probably Pliocene sandy limestones and marls.
Fig. Bt1e-3. Location. Geographic. 52° E, 23°55' N, United Arab Emirates Geologic. Tertiary Rub at Khali Basin in the stable region of the Arabian Plate Source. Vesey-Fitzgerald D (1951) From Hasa to Oman by car. Geographical Review, American Geographic Society, October 1951, pp 544–560, figs 2 and 3 Comments. Photo shows a heavy vehicle that has broken through the salt crust and sunk up to the axles in mud on the Sabkha Mutti on the Persian Gulf coast.
Bt1 · Lagoons
Fig. Bt1e-4. Location. Geographic. 81°07' E, 06°08' N, southeastern Sri Lanka Geologic. Tanamalwila Archaean Peneplain of the sub-plate Vertical Airphoto/Image. Type. b/w pan, airphoto Scale. 1: 40 000
Acquisition date. Not given Source. Personal archive Comments. The photo subscene covers a storm surge and tsumani-susceptible sabkha depression at Hambantota. The depression is enclosed by a Ec3 dune-crowned Bw3.1 bay barrier beach.
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Division 4 · Surficial Deposits
Fig. Bt1e-5. (Caption on p. 766)
Group B · Marine Littoral Systems
Bt1 · Lagoons
Fig. Bt1e-6. (Caption on p. 766)
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Division 4 · Surficial Deposits ▼
Fig. Bt1e-5. Location. Geographic. 72°45' W, 19°14' N, west coast Haiti Geologic. Greater Antilles Deformed Belt of Caribbean Plate Vertical Airphoto/Image. Type. b/w pan, stereo triplet Scale. 1: 44 000 Acquisition date. 1978 Source. IGN – Photothèque Nationale, France Comments. This stereomodel at a locality named Grande Saline shows a dark band of Bt1c mangroves enclosing a turbid bay of the elongate delta of the south arm of Artibonite River. The mangroves screen a zone of wet Bt1e sabkha on the landward side. The bright peninsula on the left is a 24 m high raised coral reef. Grids of salt evaporation and extraction pans are located along the spit beach.
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Fig. Bt1e-6. Location. Geographic. 70°30' E, 23°10' N scene center, western India Vertical Airphoto/Image. Type. MSS 80 m resolution Scale. 1: 1 000 000 Acquisition date. 29 January 1973 Source. USGS Comments. The bluish areas in this Landsat scene are partly inundated, supratidal deltaic saline mudflats in tectonic depressions in the Katchchh region at the southern end of the Thar Desert. The zone in the northwest is named Great Rann, and the estuarial shaped zone on the east is Little Rann which terminates in the Gulf of Kutch in the southwest. “The clay-rich sediments comprising these mudflats are transported into the Gulf of Kutch by strong longshore currents from the mouths of the Indus River, (200 km) to the northwest.” (Short and Blair, 1986, p 398). These flats are inundated only part of the year, the remaining time becoming regions of intense evaporation and deposition of evaporite minerals. The beige land area separating the Ranns is Kutch proper, consisting of flat-lying Jurassic to Miocene rocks, mainly sandstones, 275–335 m elevation. The brown area to the southeast appears to be dry thorn forest on the Late Cretaceous to Eocene Deccan lavas of the Kathiawar Peninsula. This is a tectonically controlled landscape whose elements are a manifestation of uplifts along major east-west normal faults reactivated from time to time, detectable in left center, and graben-like sabkha filled depressions reflecting oblique-cutting NE/SW subordinate faults developed during various tectonic events.
Group B · Marine Littoral Systems
Bt1 · Lagoons
Fig. Bt1g-1. Location. Geographic. 05°46' E, 52°38' N, central Netherlands Source. Unattributed Comments. These two perspective airphotos illustrate a result of the construction of a polder, in this case the 48 000 ha Northeast Polder. The upper photo looking south shows the 2.5 km long island of Schokland as it stood in the Ijsselmeer around 1939, with about 800 inhabitants.
In 1940, the four year project to construct the 54 km long dyke enclosing the polder area was completed. Pumping to drain the polder was completed in 1942. The lower photo looking north, probably taken around 1950, shows the island incorporated into the polder, kept as an undeveloped green space surrounded by agricultural land. See the Landsat scene of similar polders developed later to the south in Fig. Bt1g-8.
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Division 4 · Surficial Deposits
Fig. Bt1g-2. (Caption on p. 770)
Group B · Marine Littoral Systems
Bt1 · Lagoons
Fig. Bt1g-3. (Caption on p. 770)
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Division 4 · Surficial Deposits
Group B · Marine Littoral Systems
▼
Fig. Bt1g-2.
Location. Geographic. 01°05' W, 46°22' N, Atlantic Coast Geologic. Embayment at contact of Brittany Massif and the Aunis Arch of the Jurassic northern Aquitaine Basin Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 25 000 Acquisition date. 1981 Source. IGN – Photothèque Nationale, France Comments. The stereomodel at Luçon-Puyravault in the Marais Poitevin covers the 38 km2 area of polder land in the center of Landsat MSS subscene Fig. Bt1g-7. The elongate outline is a 500 m wide ridge of limestone. In the Marais itself, individual farms are sited at intervals along the major collector drainage ditches such as the two that cut across the ridge. Field drainage ditches are both tiled and opened surface as in Figs. Bc3-6 and Bc3-7. ▼
Fig. Bt1g-3.
Location. Geographic. 02°57' E, 42°49' N, Languedoc Geologic. Quaternary Bc1 coastal sediments Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 30 000 Acquisition date. 1974 Source. IGN – Photothèque Nationale, France Comments. A stereomodel shows three areas of dark-toned wetland at the south west margin of the 40 km2 tideless Leucate Lagoon. The two north areas are reverting to salt marsh following their abandonment as drained agricultural zones. Abandonment has resulted from a condition of hyper salinity of the lagoon water brought about by engineered enlargement of the inlet (graus) to provide navigation to small ports at the north end of the lagoon. Regional salinity conditions are enhanced by desiccating winds from northwest in summer. (however, these salinity levels have led to a development of aquaculture – oysters, mussels – in the center of the lagoon – off photo cover). The high evaporation rates of summer temperatures lead to deoxygenation of water through enhanced bacterial activity and liberation of toxic substances. Harmful mosquito infestations are a related seasonal health hazard. Three short segments, 700 m to 1 000 m long of white, isolate Bw4 paleo-beach ridges occur in the second abandoned area. The town of Salses with its Spanish fortress (1497–1504) is visible on the west margin of the annotated photo. See Landsat subscene Fig. Bt1c-9.
Fig. Bt1g-4.
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770
Location. Geographic. 03°30' E, 43°19' N, Languedoc Geologic. Cretaceous and Pliocene sediments Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 25 000 Acquisition date. 1968 Source. IGN – Photothèque Nationale, France Comments. The stereomodel at Agde is centered on the polderized lagoon of the 3 km2 Etang de Bagnas south of the Bassin de Thau. Photo evidence suggests it may have been a salt extraction area that was in an abandoned state at the time of photography. The smaller area also appears disused. Previous activity is undetermined. The canal that crosses the photo between the two areas is the eastern terminus of the Canal du Midi. The canal is a 240 km waterway that connects the Atlantic, via the Garonne River, to the Mediterranean. It was constructed between 1667 and 1681. It appears also in Fig. L3-4.
Bt1 · Lagoons
771
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Division 4 · Surficial Deposits
Fig. Bt1g-5. (Caption on p. 774)
Group B · Marine Littoral Systems
Bt1 · Lagoons
Fig. Bt1g-6. (Caption on p. 774)
773
Division 4 · Surficial Deposits
Group B · Marine Littoral Systems
▼
Fig. Bt1g-5.
Location. Geographic. 03°19' E, 43°17' N, Languedoc Geologic. Quaternary Bc1 coastal sediments Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 25 000 Acquisition date. 1968 Source. IGN – Photothèque Nationale, France Comments. The stereomodel 10 km southeast of Béziers shows a group of artificially drained marsh areas in an analogous coastal setting to those occurring 60 km to the south, pictured in Fig. Bt1g-3. The poldered areas are on Quaternary sediments in the valley of the River Orb, with the Grande Maire lagoon separating active and inactive units. The northeast corner at the village of Portiragne consists of Pliocene marine sediments. The area along the Bw3 barrier beach has been developed for vacation homes. The coverage of these photos is shown on the Landsat image of Fig. Bc4-3.
Fig. Bt1g-7.
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774
▼
Fig. Bt1g-6. Vertical Airphoto/Image. Type. MSS 80 m resolution Scale. 1: 555 000 Acquisition date. October 1975 Source. USGS Comments. Landsat subscene shows the setting of the Venice Lagoon and its enclosing Bw3 barrier beaches on a Bc1 coastal plain of the northeast section of the Po Plain of subsidence at the head of the Adriatic Sea. The lagoon is 50 km long by 10 km wide in the north and 15 km wide in the south. The blue colour reflects the shallow bottom muds. The blue patch of the city of Padua is visible 20 km inland, and the first ranges of the limestone Pre-Alps of the upper Piave Valley are in the northwest. See also Figs. Fw4-4 and Mv5-2.
Location. Geographic. 01° W, 46°20' N, western France Vertical Airphoto/Image. Type. MSS 50 m resampled resolution Scale. 1: 665 000 Acquisition date. September 1981 Source. Personal archive Comments. An extensive area of reclaimed land, indicated Bt1g, is delineated in the center of this Landsat subscene at the northern extremity of the Aquitaine Basin. The red band of land across the north of the image is the south margin of the Brittany Massif labelled J3.2. The reclaimed area is the Marais Poitevin, 70 km long by 25 km broad. It is a depression in the regional Upper Jurassic limestone plateau caused by reactivation during the Tertiary of faults in the Hercynian basement. Marine clays were deposited in the depression by the post-glacial Flandrian transgression. Drainage of the extensive salt marshes developed on the sediments was undertaken by the construction of sea dykes in the twelfth century and continued, following a period of disuse, by the cutting of a series of canals towards the end of the 18th century. The poldered area now consists of two zones, distinguished spectrally in the image; a bluish-speckled drier area of cropland and pasture covers 2/3 of the land; the remaining area, which appears bright red, consists of hedged, wetter market gardening fields. The higher moisture is maintained by surrounding dryland streams flowing into the margins of the depression, particularly at the east end. The inset frame locates the coverage of the stereomodel of Fig. Bt1g-2.
Bt1 · Lagoons
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Division 4 · Surficial Deposits
Group B · Marine Littoral Systems
Bt1 · Lagoons ▼
Fig. Bt1g-8. Vertical Airphoto/Image. Type. MSS 80 m resolution Scale. 1: 370 000 Acquisition date. August 1978 Source. USGS Comments. A major example of polder development is presented in this Landsat subscene of two contiguous units of four constructed to date in the Netherlands. The northern unit, densely agricultural, is 54 000 ha. East Flevoland, constructed between 1950 and 1957, enclosed by 90 km of dykes. The attached southern unit showing bare land in August 1978, is 43 000 ha South Flevoland, constructed from 1959 to 1968, enclosed by 70 km of dykes. The 4 km by 5 km bright rectangle on the west side of East Flevoland is Lelystad, the administrative and industrial center for the entire Dutch polder project, it is named after Dr. C. Lely, the project conceptor. The first two polders, off-scene, Wieringer, 20 000 ha, and Noordoost, 48 000 ha, were constructed between 1927 and 1930, and 1937 to 1942 respectively. A last unit, Markerwaard, to be 56 000 ha, northwest of South Flevoland, is still in planning and design stages. Collectively, these five polders will have increased the cultivated area of Holland by 10%. They lie from 2 to 6 m below sea level and are kept dry by a system of diesel and electric pumps, three around East Flevoland, and the same number for the South unit. In addition to dyking and pumping, another of the major requirements preceding usability of the reclaimed land has been desalination of the marine clay soil by leaching and spread of gypsum, which forms a highly soluble compound with the sodium chloride. Soil compaction brought about by land drainage has caused significant land subsidence. In a number of areas this can attain 50 to 100 cm. Local structures then require 5 m long piles. The marine environment in which the entire reclamation project is located in the tidal accumulation plain of the Zuider Zee, a basin of the North Sea, the remnant of which is now named Ijsselmeer and is protected from North Sea storms by the 30 km long Afsluitdijk 50 km northwest of these polders. Amsterdam, with its port installations on the North Sea Canal can be seen 20 km west of the South Polder. The extensive dark-toned land area on the east margin of the image is an infertile scrub and brush covered glacial morainic mass. See also Fig. Bt1g-1.
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Division 4 · Surficial Deposits
Sub-group Bc Coastal Plains Bc1
Bc1 Plains of Marine Sediments Characterization Coastal plains are underlain by repetitive sequences of Cenozoic marine deposits. These represent transgressiveregressive cycles of sedimentation caused by eustatic or tectonic changes in sea level. Plains of recent marine sediments occur on surfaces that are emerged portions of continental shelves. Lagoons Bt1 are a transitional zones between the plains and the present continental shelf. The sediments are not fixed in time and space and migrate laterally and vertically. They are relatively thin, overlying the older substrates. Typical thicknesses of about 10 m occur in the Netherlands and on the French Atlantic coast. They consist of various unconsolidated well-stratified beds of dominantly siliclastic fine sands, silts and cohesive clays. They were deposited during a eustatic marine transgression (Flandrian) following the last (Wisconsinan, Würm) continental glaciation, 30 000–10 000 a. In a regional setting the marine plains can often be seen to occur between embayed coastal river valleys. Strata have a gentle seaward dip generally 2 m. The subsidences are irreversible, with associated susceptibilities to flooding and storm surges in such low-lying coastal areas, as occurred just to the east in Sept. 2005. See Verbeek and Clanton (1981).
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Division 4 · Surficial Deposits
Group M · Mass Movement Materials
Fig. Mv5-2. Location. Geographic. 12°20' E, 45°26' N, at Venice Geologic. Fv2 alluvial plain and Bt1 lagoon Vertical Airphoto/Image. Type. InSAR Acquisition date. 1993–2000 Source. esa Comments. The satellite image shows subsidence (mm yr–1) on the Lido Bw3 barrier beaches and landward of the Venice Lagoon for the period 1993–2000.
Using differential interferometric SAR processing, subsidence rates can be monitored over time periods spanning several years. However, the technique can only be applied to areas that are stable in terms of phase coherence. In this scene these are towns and villages in the lower alluvial plain. See also Fig. Bt1g-6.
Mv5 · Subsidence Zones, Gradual
Fig. Mv 5-3. Location. Geographic. 118°14' W, 33°45' N, Southern California, USA Geologic. Bc4 fluviomarine plain Source. Courtesy City of Long Beach, California Comments. The photo shows flooding in the man-made harbour of Los Angeles. The flooding was caused by subsidence resulting from withdrawal of oil from the Wilmington oil sands that began in the 1930s near San Pedro Bay. By the 1940s and 1950s subsidence was progressing at the rate of 30 to 60 cm yr–1. As subsidence continued and reached 7 m lateral ground movements it broke oil, water and sewage pipes, pavements cracked and bridges had to be rebuilt to keep them above the invading sea water.
Fig. Mv5-4. Location. Geographic. 119°30 'W, 35°20' N, Great Valley, California Geologic. Upper Cretaceous and Cenozoic sedimentation in intermontane basin Vertical Airphoto/Image. Type. ERS 1,2 Source. Courtesy of Vexcel Canada Inc. Comments. This image shows land subsidence data from withdrawal of hydrocarbons from an oilfield near Belrige, California by applying a radar technique known as Interferometry to ERS 1 and 2 data. The DEM was then draped with colour imagery from Landsat and grey scale imagery from IRS.
The industrial harbour district became laced with dykes and retaining walls. Over 50 km2 of land were thus affected.
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Group M · Mass Movement Materials
Mv5 · Subsidence Zones, Gradual ▼
Fig. Mv5-5. Location. Geographic. 68°45' W, 16°49' S, western Bolivia Geologic. Altiplano of Central Andes Vertical Airphoto/Image. Type. b/w pan airphoto Scale. 1:40 000 (in CD-ROM) Acquisition date. 18 May 1958 Source. Cordova EV (1992) La Fotografia Aerea y su Aplicacion a Estudios Geologicos y Geomorfologicos – Tomo II. Universidad Mayor de San Andres, La Paz, Bolivia, modelo estereoscopico 22 Comments. The stereomodel shows the pattern of pockmark waterhole solutional evidence of gradual subsidence in argillaceous gypsum evaporite sediments in a Holocene L1 paleolake. Location is in the tectonic trough of lake Titicaca, 20 km southeast of the lake. See also Figs. H1-1, L1-2, and karst solution in Fig. Mv5-7.
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Division 4 · Surficial Deposits
Fig. Mv5-6. (Caption on p. 952)
Group M · Mass Movement Materials
Mv5 · Subsidence Zones, Gradual
Fig. Mv5-7. (Caption on p. 952)
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Division 4 · Surficial Deposits ▼
Fig. Mv5-6. Location. Geographic. 112°12' W, 59°53' N, northeast Alberta Geologic. Craton cover sediments of Great Slave Plain Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 54 000 Acquisition date. Not given Source. Courtesy of Natural Resources Canada, NAPL A 24075–86, 87 Comments. A stereomodel at Salt River shows salt flats that are related to Mid Devonian H1 gypsum and anhydrite evaporites which regionally underlie Kp1 karstic limestones of the same age (note the sink holes). The salt emerges from subterranean water flow locally as a spring at the base of the horizontally-bedded limestone escarpment in the north of the photos. Precipitation sinks through fractures in the limestone and dissolves the evaporites. This underground solution and associated rock deformation and collapse poses hazards to present and planned regional resource developments. These formations underlie the Athabaska oil sands and their deformations disturb the oil sand beds in places. The integrity of planned hydroelectric reservoirs on the Slave River to the south might also be affected by any disturbances in these rock formations.
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Fig. Mv5-7. Vertical Airphoto/Image. Type. b/w pan airphoto Scale. 1: 63 360 Acquisition date. Not given Source. Ray RG (1960) Aerial photographs in geologic interpretation and mapping. USGS PP 373, p 126, fig 68 Comments. Stereomodel shows a K3 karst plain in Texas with a high concentration of solutional sinkholes. Area B consists of W1 sandstones and marls. Figure K3-2 at same scale illustrates the range in sizes of solutional sinkholes.
Group M · Mass Movement Materials
Ml1 · Rock Block Glides
Sub-group Ml Lateral Spreads Ml1 Rock Block Glides
“Fixed installations incapable of surviving increased tilt (e.g., towers) are frequently at risk from the typical block slide. All linear features such as roads, railways, power, gas and telephone lines crossing the block will be damaged beyond repair.” (Ibsen 1996).
Characterization
Reference
Rock block glide mass movement occurs on gentle slopes where a slow plastic deformation occurs in a subsurface material overlain by a more coherent thick surface rock mass. The upper layer is broken up into horst and grabenlike block structures by the movements of the underlying material and slides outward. The spreading of the surface rock is accompanied by its general subsidence into the softer underlying material.
Ibsen ML, Brunsden D, Bromhead E, Collison A (1996) Block slide. In: Dikau R, Brunsden D, Schrott L, Ibsen JL (eds) Landslide recognition. John Wiley & Sons, Ltd., Chichester, pp 64–77
Geohazard Relations The areal extent of block glides is often considerable and can narrow or block valleys and deflect streams. The drainage anomaly usually results in increased stream erosion at the point where the spread blocks the valley, which in turn results in development of numerous local smaller rotational slides.
Fig. Ml1-1. Location. Geographic. 102°35' E, 57°40' N, central Siberia, Russia Source. Zaruba Q, Mencl V (1969) Landslides and their control. Elsevier and Academia Publishing House of the Czechoslovak Academy of Sciences, p 72, fig 5-34 Comments. Figure is a section of the lateral extension of a now stabilized rock block glide at the junction of the Llima
Select Bibliography Cruden DM, Varnes DJ (1996) Landslide types and processes. In: Turner AK, Schuster RL (eds) Landslides: Investigation and mitigation. Transportation Research Board, National Research Council, Washington, D.C., Special Report 247, p 62 McGill GE, Stromquist AW (1979) The grabens of Canyonlands National Park, Utah: Geometry, mechanics, and kinematics. J Geophys Res 84(B9):4547–4563 Rohn J, Resch M, Schneider H, Fernandez-Steeger TM, Czurda K (2004) Large-scale lateral spreading and related mass movements in the North Calcareous Alps. Bulletin of Engineering Geology and the Environment 63(1):71–75 Zaruba Q, Mencl V (1969) Landslides and their control. Elsevier, New York, pp 70–72
and Angara Rivers on the craton cover rocks of the Angara Plateau. A 100 m thick sheet of a diabase sill (“3” on section) (an intrusive igneous rock, also called dolerite) lies and glides on Carboniferous shales (“2” on section). The river cut through the diabase and exposed the shales. “1” on section are Carboniferous S1 sandstones; “s” are sites of borings.
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Division 4 · Surficial Deposits
Group M · Mass Movement Materials
Fig. Ml1-2. Location. Geographic. 109°55' W, 38°10' N southeast Utah, USA Geologic. Fault zone in Permian sediments of central Colorado Plateau Source. Commins DC (2003) Reconstruction of fault growth using drainage development in the Canyonlands Graben, Utah. Ph.d. thesis, Imperial College, University of London, 336 p Comments. This figure is a DEM of the 17.1 Canyonlands Grabens also known as the Needles Fault Zone in Canyonlands National Park. One of North America’s largest landslides, it forms an active extensional fault array covering 200 km2 southeast of the Colorado River. The fault zone is a 450 m thick sequence of competent Paleozoic sedimentary rocks that have glided over evaporite salt beds down a 4° dip towards the Colorado River, off the west-dipping flank of the Monument Upwarp. Growth of this fault array within the last 0.5 to possibly 0.1 Ma has produced this group of linked normal fault geometries. Figure Ml1-3 is a stereo photo pair within the fault zone.
Fig. Ml1-3.
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Location. Geographic. 109°55' W, 38°10' N, southeast Utah Geologic. Fault zone in Permian sediments Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 82 000 Acquisition date. Not given Source. Unspecified U.S. government agency Comments. This stereomodel covers the central section of the DEM of Fig. Ml1-2. The faults are Structural Unit 17 grabens, formed by extension due to the flow of the underlying salt beds. They are 150 to 200 m in width and 25 to 75 m in depth.
Ml1 · Rock Block Glides
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Division 4 · Surficial Deposits
Sub-group Mc Diagonal Creeps Mc1
Mc1 Colluvial Mantle Movement Zones
Group M · Mass Movement Materials
Geohazard Relations Structures resting on slope creep zones are subjected to sustained lateral stresses and may be gradually displaced downslope. Use of digital terrain models (DTMs) to locate slopes >15° in Mc1 areas would be one method to avoid the hazard.
Characterization Select Bibliography Colluvium is a rock surface product of climate dependent factors (temperature conditions and availability of water) of mechanical disintegration and chemical decomposition weathering processes, e.g. see Unit Variant X1.4. Colluvial mantle-movement zone is the result of slow downslope movement of the sediments on hillsides under the influence of gravity, not carried by water, ice or wind. The movement is termed creep and consists of the deformation of an approximately 1 meter thick surface layer of colluvium by climatically-controlled expansion and contraction processes: wetting and drying; heating and cooling; freezing and thawing. Heavy rain can accelerate creep to landslips. As a photogeological facies, hillslopes zones affected by creep are generally only mappable on airphotos at scales of 1:10 000 to 1:5 000. As in mid-latitude environments, measurements of soil creep in deep-weathering wet tropical regions also show a drop to zero at a depth of less than one meter.
Bloom AL (1978) Geomorphology. Prentice Hall, Englewood Cliffs, NJ Brunsden D (1994) Mass movement types. In: Goudie A, Atkinson BW, Gregory KJ, Simmons IG, Stoddart DR, Sugden D (eds) Encyclopedic dictionary of physical geography, 2nd edn. Blackwell Reference, Oxford, p 325 Clarke ML, Vogel JC, Botha GA, Wintle AG (2003) Late Quaternary hillslope evolution recorded in eastern South African colluvial badlands.Palaeogeography,Palaeoclimatology,Palaeoecology 197:199–212 Finlayson BL (1985) Soil creep: A formidable fossil of misconception. In: Richards KL, Arnett RR, Ellis S (eds) Geomorphology and soils. Allen and Unwin, London, pp 141–158 Gerrard AJ (1981) Soils and landforms. Allen and Unwin, London, pp 55–59 Gray DH, Sotir RB (1996) Biotechnical and soil bioengineering slope stabilization: A practical guide. Wiley-IEEE Kienholz H (1978) Maps of geomorphology and natural hazards of Grindelwald, Switzerland, scale 1 : 10 000. Arctic and Alpine Research 10:169–84 Mollard JD, Janes JR (1983) Airphoto interpretation and the Canadian landscape. Surveys and Mapping Branch, Department of Energy, Mines and Resources, Canada, p 72 Okagbue CO (1984) Predicting landslips caused by rainstorms in residual/ colluvial soils of Nigerian hillside slopes. Natural Hazards 2(2):133–141 Shelton JS (1966) Geology illustrated. Freeman, San Francisco, p 126
Fig. Mc1-1. Source. Reprinted by permission of Waveland Press, Inc. from Bloom AL (1998) Geomorphology, 3rd edn. Waveland Press, Inc., Long Grove, IL, p 174, fig 9-5, (reissued 2004), all rights reserved Comments. Block diagram figure shows common field evidences of creep as a process of colluvial mantle movement (e.g., see Fig. Mc1-4).
Mc1 · Colluvial Mantle Movement Zones
Fig. Mc1-2. Source. John S. Shelton Comments. This photo shows how creep can deform weak sedimentary rocks. The road cut is in Miocene sandy shales near Los Angeles, California, it displays the bending of the outcropping strata in the upper part of the cut.
Fig. Mc1-3. Source. LAR, October 1991 Comments. This photo pair shows an area of rough-surfaced creep 40 m broad by 50 m long on a moderate slope in weak, locally frostsusceptible, Lower Jurassic marly shales. These zones of creep locally can be incipient Ms2 debris slides. The site is at the foot of Mt. Eiger at Grindelwald, in a broad valley of marly shales of the Helvetic Nappes in central Switzerland. The inset frame in the upper photo gives the coverage of the closeup view. See slumps and debris flows in this same weak formation in Figs. Ms3-3 and Mf3-4. These movements are common inconveniences in the local pasture lands associated with these rocks.
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Fig. Mc1-4. Source. LAR, October 1974 Comments. This photo shows deformed tree trunk indicators of creep on a hillslope at Heiligenblut in the Pennine Alps of south central Austria.
Fig. Mc1-5. Source. LAR Comments. This photo shows biotechnical stabilization in the Austrian Alps using live staking on a graded slope.
Group M · Mass Movement Materials
Ms1 · Planar Rock Slides
Sub-group Ms Slides Ms1 Planar Rock Slides Characterization Rock slides may occur in any rock type; are largely related to slope-exposed bedding planes, joints, faults and cleavage or schistosity planes with unfavourable orientations relative to the slope. They occur because the forces creating movement exceed those resisting it. Slides are generally initiated by the coincidence of such inherently unstable slopes with a weather-related trigger or earthquake. The displaced masses consist of irregular and stacked bedrock blocks or coherent sheets of large rock blocks.
Geohazard Relation As agents of rapid sliding, deposition and flooding, landslides in areas with human resources can result in considerable property damage and significant loss of life. Direct annual cost of landslide damage has been estimated at $2 billion in the USA.
Select Bibliography Brabb EE (1991) The world landslide problem. Episodes 14:52–61 Bromhead EN (1997) The stability of slopes. Spon Press, London De La Ville N, Diaz AC, Ramirez D (2002) Remote sensing and GIS technologies as tools to support sustainable management of areas devastated by landslides. Environmenta, Development and Sustainability 4(2):221–229 Evans SG, DeGraff JV (2002) Catastrophic landslides: Effects, occurrence, and mechanisms. Geological Society of America Fookes PG, Dale SG, Land J (1991) Some observations on a comparative aerial photography interpretation of a landslipped area. Quarterly Journal of Engineering Geology 24:249–265
Fig. Ms1-1. Source. Howes DE, Kenk E (1988) Terrain classification system for British Columbia, rev. edn. MOE Man. 10. Recreational Fisheries Branch, Ministry of Environm., p 65, fig 34 Comments. Figure is a diagram that illustrates the common elements of a planar jointcontrolled rock slide with a weak layer failure surface. The detached blocks upslope are coherent, become disintegrated on the way downslope, and accumulate as stacked blocks at the foot of the slope.
Glade T, Crozier MJ (2005) Landslide hazard and risk. Wiley Hutchinson JN (1988) General report. Morphological and geotechnical parameters of landslides in relation to geology and geohydrology. Proceedings of the 5th International Symposium on Landslides, Lausanne, vol 1, pp 3–35 Lacerda WA (2004) Landslides: Evaluation and stabilization. Taylor & Francis Lee EM, Jones DKC (2004) Landslide risk assessment. Thomas Telford Leighton FB (1976) Geomorphology and engineering control of landslides. In: Coates DR (ed) Geomorphology and engineering. Dowden, Hutchinson & Ross, Inc. Mantovani F, Soeters R, van Westen CJ (1996) Remote sensing techniques for landslide studies and hazard zonation in Europe. Geomorphology 15:213–225 Nichol JE, Shaker A, Wong MS (2006) Application of high-resolution stereo satellite images to detailed landslide hazard assessment. Geomorphology 76(1–2):68–75 Poisel R, Bednarik M, Holzer R, Pavel L (2005) Geomechanics of hazardous landslides. Journal of Mountain Science 2(3)211–217 Rib TH, Liang T (1978) Terrain evaluation for landslide inves-tigations, 34 basic factors, recognition and identification, landslide analysis and control. Transportation Research Board, National Academy of Sciences, Washinton, D.C., Special Report 176 Schultz AP, Bartholomew MJ, Lewis SE (1991) Map showing surficial and generalized bedrock geology and accompanying sidelooking airborne radar image of the Radford 30' × 60' quadrangle Virginia and West Virginia. USGS Map 1–2170-A, 1 : 100 000 Schulz WH, Cotton W (2002) Use of detailed mapping and monitoring of a landslide to permit safe occupation of surrounding residences. GSA, vol 34, no 6 Singhroy V, Mattar KE, Gray AL (1998) Landslide characterization in Canada using interferometric SAR and combined SAR and TM images. Advances in Space Research 21(3): 465–476 Soeters R, Cornelis J, van Westen CJ (1996) Slope instability recognition, analysis and zonation. In: Turner AK, Schuster RL (eds) Landslides: Investigation and mitigation. Transportation Research Board, National Research Council, Washington, D.C., Special Report 247, pp 147–149 Sorriso-Valvo M, Gulla G (1996) Rockslide. In: Dikau, R, Brunsden D, Schrott L, Ibsen ML (eds) Landslide recognition. John Wiley & Sons, Ltd., Chichester, pp 85–96 Voight B (ed) (1978) Rockslides and avalanches 1, Natural Phenomena. Elsevier
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Ms1
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Division 4 · Surficial Deposits
Group M · Mass Movement Materials
Fig. Ms1-2. Source. LAR, April 1974 Comments. Photo of planar slide blocks and debris at the foot of a 200 m high stock of granite. The mass is of Late Proterozoic age in the Hoggar Massif of southeast Algeria. The blocks are spalling from stress release parallelbedded joints and vertical tension joints of geostructure Unit 18. The intrusive stock is in discordant contact with the foliated metamorhic country rock, syn or post tectonic emplacement is unspecified.
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Fig. Ms1-3. Source. USGS Comments. A planar rock slide of moderate displacement of intact blocks photographed at an undisclosed location. In the absence of site-specific information the slide is interpreted as consisting of coherent slabs in steep slopeexposed bedding plane surfaces of thin-bedded sedimentary rocks. The figure gives scale.
Ms1 · Planar Rock Slides
Fig. Ms1-4. Location. Geographic. 73°20' E, 34°30' N, Azad Kashmir, Pakistan Geologic. Alpinotype ranges of crystalline rocks with Himalayan overprint Vertical Airphoto/Image. Type. SPOT 4, pan, 10 m resolution Scale. 1:50 000 nominal Acquisition date. 21 September 2005 Source. International Charter for Space and Major disasters. CNES 2005, distribution by Spotimage
Comments. This interpreted image shows the occurrence of landslides generated on 8 October 2005 by an earthquake of magnitude 7.6 that struck on the India-Pakistan border. The epicenter was located about 95 km northeast of Islamabad. Shocks were felt over a radius of 300–400 km. On 21 October, Pakistani authorities reported casualties at 49 700 dead and over 74 000 injured. The UN estimated 1 million people have been left homeless. In this area at Balakot sites of newly detected Ms1 or Ms2 landslides are mapped in yellow. Sites of reactivated landslides are mapped in red.
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Group M · Mass Movement Materials
Ms1 · Planar Rock Slides ▼
Fig. Ms1-5. Location. Geographic. 0°10' E, 42°47' N, central Pyrenees Geologic. Axial zone of Hercynian/Alpine tectogenic belt Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 60 000 Acquisition date. 1980 Source. IGN – Photothèque Nationale, France Comments. This stereomodel 40 km southeast of Lourdes shows a group of slides delineated in interbedded Devonian limestones and shales at the Piau-Engaly ski development. The latter is located on a Paleozoic Np4.3 granitic stock, other small stocks occur in the area. Kidney-shaped Lac Cap-de-Long is a dammed reservoir. W1.3 – D are dissected Devonian folded interbedded limestones and shales. The larger Np4.2 – Pz is a Paleozoic glaciated granite batholith.
Fig. Ms1-6. Location. Geographic. 07°11'56'' E, 46°10'35'' N, Rhone Valley, Switzerland Geologic. Intermontane fault valley between Pennine basement Nappe and Helvetic cover alps Source. esa Service for Landslide Monitoring (SLAM) Comments. This ERS 2 image is at the village of Leytron, 485 m, in the middle Rhone Valley between Sion and Martigny. Local geology consists of the steep thrusted front of the Pennine basement Nappe in lower right, Fv alluvial valley fill and, on the north, folded Mid Jurassic (Aalénien) calcareous shales and slates with beds dipping 35° to southeast. In the very center of the scene, just left of the coloured patch is the historical Montagnon slide in the shales, it is not clearly evident topographically in this radar image, but is well resolved in electro optical imageries. This largest slide site in Valais Canton is one of eight in Switzerland chosen to develop landslide susceptibility mapping using esa SLAM techniques of mathematically combining multiple radar images of the same site in such a way that tiny changes in the landscape such as deformation of materials occurring between images are highlighted (interfereometry). The image shows preliminary SLAM results. The coloured points represent land movement measured via interferometry in millimeters per year: from –5 mm yr–1 in purple, on a scale up through red and orange, with light green around zero, up to blue at +1 mm yr–1.
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Ms1.1
Division 4 · Surficial Deposits
Ms1.1 Planar Rock Slides, Inactive Characterization Some old rock slides degrade to a state of ultimate stability but many retain low stability because the shear surface has been reduced to residual strength with little or no cohesion. Reactivation has no peak strength to overcome. Inactive slides may be more difficult to detect and map as their traces become less sharply defined and progressively attenuated. Weathering and revegetation obscure the original structure. “It takes of the order of a thousand years for a major rockslide to become sufficiently overgrown by natural vegetation in the Rockies to be obscured in a reconnaissance survey. The rate of growth depends on the climate and on the nature of the slide debris. Debris from mudstones, shales, schists and other materials that weather quickly to clay minerals promotes rapid recovery of the natural vegetation; slide debris with large blocks of limestone or sandstone is more persistent”. Cruden (1985).
Group M · Mass Movement Materials
Geohazard Relations Prediction of landslide hazard for areas not currently subject to movement is based on the assumption that hazardous phenomena that have occurred in the past can provide useful information for prediction of future occurrences. Proper field assessment of the dormant character is of considerable importance in construction areas because reactivation may begin if excavations decrease support from below by re-steepening any part of the slide, or by loading the slope to increase the pressure exerted on the slide mass.
Reference Cruden DM (1985) Rock slope movements in the Canadian Cordillera. Canadian Geotechnical Journal 22:528–540
Select Bibliography Waltham T (2002) Foundations of engineering geology, 2nd edn. Spon Press, London, p 70
See also Geounit Ms1.
Fig. Ms1.1-1.
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Location. Geographic. 08°54' E, 42°03' N, Corsica Geologic. Paleozoic granite of terrane of European basement Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 25 000 Acquisition date. 1982 Source. IGN – Photothèque Nationale, France Comments. A stereomodel 22 km northeast of Ajaccio shows a 1.5 × 1 km inactive slide in weathered and dissected intrusive granite rocks coded Np5 and Np5.1. The latter is interpreted as being more intensely weathered and dissected than the Np5 area. A strong fracture or fault trace bounds the north side of the failure which is situated within 0.5 km of the access road to Vero Village.
Ms1.1 · Planar Rock Slides, Inactive
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Division 4 · Surficial Deposits
Fig. Ms1.1-2. (Caption on p. 968)
Group M · Mass Movement Materials
Ms1.1 · Planar Rock Slides, Inactive
Fig. Ms1.1-3. (Caption on p. 968)
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Division 4 · Surficial Deposits ▼
Fig. Ms1.1-2. Location. Geographic. 72°14' W, 19°08' N, central Haïti Geologic. Greater Antilles Deformed Belt of Caribbean Plate Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 44 000 Acquisition date. 1978 Source. IGN – Photothèque Nationale, France Comments. Four types of apparently inactive mass movements are delineated in this stereomodel 50 km east of St. Marc, along the nose and limbs of a probably faulted anticline in Paleogene rocks: Ms1.1 rock slide; Ms2 debris slide; Ms3.1 rock slump; and Mv1 rock fall. The structure at 1 034 m elevation is composed of interbedded lavas and pyroclastics of the Chaine des Cahos. X2 – Pg are Paleogene lavas; S2 – Og are Oligocene silts and shales.
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Fig. Ms1.1-3.
Location. Geographic. 0°14' W, 42°58' N, western Pyrenees Geologic. Axial zone of Hercynian/Alpine tectogenic belt Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 70 000 Acquisition date. 1979 Source. IGN – Photothèque Nationale, France Comments. A group of slides and gelifluction on glacial till and Lower Devonian sandy shales on the slopes above the Gave d’Arrens valley 20 km southwest of Lourdes. The lower part of the largest mass, 2 km long, is cultivated above the villages of Arrens and Marsous. The shales are relatively weak, dissected, and are bordered by steeply dipping limestone strata to north and south. This figure is 40 km east of Fig. Kp1.1-4 and 30 km west of Fig. Ms1-5.
Group M · Mass Movement Materials
Ms2 · Debris Slides
Ms2 Debris Slides Characterization Debris slides are the rapid translational downslope movement of relatively dry Mc1 colluvium generally on slopes ranging from 25° to 45°. The failure surface is generally at the contact between the regolith and the underlying bedrock.Where sufficient moisture is present, the slide may become a Mf3 mud flow. “Failures are commonly due to an increase in pore water pressure following heavy rains, which reduces the shear strength of surficial formations … A frequent observation with debris slides is that they can burst explosively out of a slope. This appears to be associated with throughflow water (downslope flow within the soil) in pedological horizons, piping or aquifers, which provide water quickly to a slope face.” (Corominas 1996). Debris slides are generally poorly detectable on vertical air photos unless the latter were acquired when the slides were fresh, shortly after the events.
Clark GM (1987) Debris flows-avalanches. GSA Reviews in Engineering Geology VII:125–138 Howell DG, Brabb EE, Pike RJ, Ransey DW, Roberts S, Hillhouse JW (1999) Landslide hazard information and the decision-making process. GSA, Annual Meeting, vol 31, no 6 Iverson RM (1998) Runout and runup of landslides with ordinary Coulomb friction. EOS Transactions, AGU 79(17) Morton DM, Alvarez, RM, Campbell RH (2003) Preliminary soil-slip susceptibility maps, southwestern California. USGS Open File 03–0017 Moser M (1978) Proposals for geotechnical maps concerning slope stability in mountain watersheds. International Association of Engineering Geologists Bull 17:100–108 Nagarajan R, Khire M (1998) Debris slides of Varandh Ghat, west coast of India. Bulletin of Engineering Geology and the Environment. Springer-Verlag, Berlin Heidelberg, vol 57, no 1 Radbruch-Hall DH, Colton RB, Davies WE, Skipp BA, Lucchitta I, Varnes D (1976) Preliminary landslide overview map of the coterminous United States. USGS, Misc. Field Studies Map MF–771 Reid E, Lahusen RG, Roering JJ (2000) Landslide dynamics captured by real-time monitoring. Abstract GSA Annual Meeting, vol 31, no 6, p 87 Reneau S, Dietrich WE (1987) Size and location of colluvial landslides in a steep forested landscape. Erosion and sedimentation in the Pacific Rim. Intern. Association of Hydrological Sciences, Publ. 165, pp 39–48 Sasaki Y, Fujii A, Asai K (2000) Soil creep process and its role in debris slide generation – Field measurements on the north side of Tsukuba Mountain in Japan. Engineering Geology 56( 1–2):163–183
“Debris slide scars are ephemeral because the scarps are smoothed by small-scale degradational processes and rill erosion and the surface of failure is blanketed with new debris. In humid climates vegetation spreads quickly over the source area. Under these conditions, recognition of debris slide scars can be made only by using large-scale aerial photographs and by detailed field work.” (Corominas 1996).
Geohazard Relations The hazard posed by a debris slide is mainly attributable to the movement of ground beneath a structure or to the physical impact of rapidly moving debris. Short and poorly vegetated slopes as well as forested areas destroyed by fire or logging generally exhibit frequent debris slides related to intense rainfall events or earthquakes. On forest-covered slopes where roots penetrate to the underlying rock, the cohesion imparted to the regolith can be significantly higher than the natural cohesion of unforested regolith. Use of DTMs to locate slopes >25° in Ms2 areas would be one method to avoid the hazard.
Reference Corominas J (1996) Debris slide. In: Dikau R, Brunsden D, Schrott L, Ibsen ML (eds) Landslide recognition. John Wiley & Sons, Ltd., Chichester, pp 97–103
Select Bibliography Bromhead EN (1997) The stability of slopes. Spon Press, London Chandler RJ (1977) The application of soil mechanics to the study of slopes. In: Hails JR (ed) Applied geomorphology. Elsevier Scientific Publishing Company, pp 157–181
Fig. Ms2-1. Location. Geographic. Eastern Nepal, southeast Tibet Source. Courtesy of Stephen and Klaudia Mandl Comments. Photo shows a debris slide site in a road cut at a point on the Friendship Highway from Kathmandu, Nepal to Lhasa, Tibet.
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Ms2
Division 4 · Surficial Deposits
Group M · Mass Movement Materials
Fig. Ms2-2. Source. Wilshire HR, et al. (1996) Geologic processes at the land surface. USGS Bulletin 2149, p 3 Comments. An air perspective photo shows a debris slide at La Conchita on the coast of southern California. The slide destroyed nine homes on 4 March 1995 following a period of heavy rains. This photo was taken two days later. The movement occurred in a 120 m high Br6 marine terrace developed in hills of poorly consolidated Tertiary and Quaternary marine sediments. The town of la Conchita lies on a lower Bc1a marine terrace 6 to 12 m above mean sea level. The community is thus also susceptible to exceptionally large storm surges and tsunamis. These have undercut and oversteepened the slopes at the base of the cliffs, making them prone to landsliding. An additional hazard factor in this area is neotectonism produced by a rising of the land by 3 mm yr–1. The deformation is related to the Pacific crustal plate being compressed and thickened in the region. Destructive debris slides recurred here in January 2005, causing 10 human fatalities, the destruction of 15 houses and damage to 16 other buildings.
Fig. Ms2-3.
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970
Location. Geographic. 130°45' W, 57°04' N, northern British Columbia Geologic. Stikinia Superterrane of Intermontane Cordilleran Belt Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 31 680 Acquisition date. Not given
Source. Base Mapping and Geomatic Services Branch, Ministry of Sustainable Resources, Government of British Columbia, Canada, BC 5157-260, 261 Comments. The stereomodel shows a 1.5 × 1.5 km debris slide in Lower Devonian volcanic rocks with a nested Ms2.1 debris avalanche that has displaced the east-flowing valley stream. An Ms1 rock slide in apparently similar rocks immediately adjoins the debris slide. Trimlines of three highland glaciers are traced. This figure is 15 km west of Fig. Mf3-11.
Ms2 · Debris Slides
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Ms2.1
Division 4 · Surficial Deposits
Ms2.1 Debris Avalanches Characterization Debris avalanches are extremely fast debris slides occurring on open very steep slopes (>35°), and as with the slide, involve only a thin (15° in Mf2.1 areas would be one method to avoid the hazard.
Characterization
Reference
Slow Earth Flows are elongate, or tongue-shaped masses with dish-shaped scars and bulging toes, in valley incisions or on open slopes of 10° to 35°, in fine residual or colluvial soils containing a significant amount of entrained water. The flows “move episodically or by sustained, relatively steady movement, primarily by sliding on a basal shear surface, accompanied by internal deformation” (Baum et al 2003). They range in size from bodies a few meters wide and less than 1 m deep to bodies more than 6 km long, several hundred meters wide and more than 10 m deep. Many flows come to rest part way down apparently uniform slopes. Waltham (2002) describes progressive failure: “Clay soil in slopes too steep or too high is locally overstressed; deforms and loses strength, passes load to adjacent soil; shear zones grow and coalesce; overall strength declines to ultimate failure of slope”.
Baum RL, Savage WZ, Wasowski (2003) Mechanics of earth flows. USGS Waltham T (2002) Foundations of engineering geology, 2nd edn. Spon Press, London, p 68
Geohazard Relations Moisture content changes in earth flow deposits make them poor foundations for any permanent structures. The sustained or repeated movement of ground beneath transportation structures crossing the toe of slow earth flows present recurring maintenance problems.
Select Bibliography Bovis MJ (1985) Earthflows in the Interior Plateau, southwest British Columbia. Canadian Geotechnical Journal 22:313–334 Cruden DM, Varnes DJ (1996) Landslide types and processes. In: Turner AK, Schuster RL (eds) Landslides: Investigation and mitigation. Transportation Research Board, National Research Council, Washington, D.C., Special Report 247, pp 64–65 Evans SG (2001) A synthesis of geological hazards in Canada. GSC Bull 548:57–58 Keefer DK, Johnson AM (1983) Earth flows: Morphology, mobilization and movement. USGS Professional Paper 1264 van Asch TWJ (2005) Modelling the hysteresis in the velocity pattern of slow-moving earth flows: The role of excess pore pressure. Earth Surface Processes and Landforms 30(4):403–411 Zaruba Q, Mencl V (1969) Landslides and their control. Elsevier, New York, pp 39–42
Fig. Mf2.1-1. ▼ Source. Keefer DK, Johnson AM (1983) Earth flows: Morphology, mobilization and movement. USGS PP 1264, fig 4 Comments. The figure is an idealized model of an earth flow showing surface and subsurface features.
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Division 4 · Surficial Deposits
Fig. Mf2.1-2. Location. Geographic. North central Colorado, USA Geologic. Gf4 glacial till in Rocky Mountain intermontane basin Source. Transportation Research Board (1996) Landslides: Investigation and mitigation. National Research Council,
Group M · Mass Movement Materials
Washington, D.C., Special Report 247, fig 2-6, p 18. Reproduced with permission Comments. A photo shows an earth flow in 1985 that passed through the base of a railway embankment at Granby 75 km northwest of Denver derailing a passenger train. The flow moved another 70 m as an Mf3 debris flow and partially dammed the Fraser River in the foreground.
Mf2.1 · Slow Earth Flows
Fig. Mf2.1-3. Location. Geographic. 121°25' W, 50°20' N, southern British Columbia Source. Brooks GR (ed) (2001) A synthesis of geological hazards in Canada. GSC Bull 548, p 57, fig 21 Comments. Air view of a large volume, slow-moving (3 m yr–1 for the period 1951 to 1972) earthflow on the Thompson River in the ThompsonFraser Valley Corridor in the Interior Plateau. It is 5.3 km long and drops 710 m in elevation. It is 670 m wide at its toe and about 150 m wide in its middle sections. The flow has developed in poorly lithified Upper Cretaceous shale sandstone and coal. Well marked lateral shear deposits on the flow boundaries indicate a progressive reduction in the size of the flow over time. Flow deposit on one side has overridden tephra indicating that most of the flow developed after 6 600 bp. The photograph taken in 2000 shows that the TransCanada Highway and the Canadian Pacific Railway track cross the toe of the landslide. Both roadways have had to be realigned repeatedly since their construction, 1884 for the railway and 1957 for the highway. The Trans-Canada Highway, relocated again in 1961, has undergone little movement since because most of the failure plane was removed during construction. Note the small Ms2 debris slide at the base of the mass by the water’s edge.
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Division 4 · Surficial Deposits
Fig. Mf2.1-4. Vertical Airphoto/Image. Type. b/w pan airphoto Scale. Indicated Acquisition date. Not given Source. Evans SG (2001) A synthesis of geological hazards in Canada. GSC Bull 548, p 58, fig 22b
Group M · Mass Movement Materials
Comments. The photo shows an old, slow (45 cm yr–1), earth flow in south-central British Columbia. The flow is derived from Cretaceous sediments and incorporated glacial till (Gf4) and Mc1 colluvium (weathered bedrock) in its movement. The deposit below the bottleneck spread out in fan shape on the valley floor.
Mf3 · Debris Mud Flows
Mf3 Debris-Mud Flows Characterization Debris and mud flows are Ms2 debris slides and Mf2 earth flows that have been modified by increased water content. The hyphenated name debris-mud flow reflects the fact that “in many cases it is not easy to be specific about the mode of movement (of these flows). In addition, one movement mode often changes into another.” (Gerrard 1990). The mass consists of cobbles and boulders embedded in a matrix of fine material, with a quantity of water that forms a slurry and moves downslope very rapidly. Where coarse debris is absent the viscous mass becomes a mud flow. Debris-mud flows form elongated masses that commonly follow pre-existing drainage ways down steep mountain slopes covered with unconsolidated weathered rock and soil debris. Where they enter trunk valleys they frequently interstratify their deposits with the fluvial sediments of Fu1 fans (see). They have a high density and viscosity compared to stream flows and, because of their high viscosity, they do not flow as far down the fans as do water transported sediments. Debris-mud flow deposits are distinguished from fan sediments in the field by their unstratified structure and lack of sorting. The flows usually form during periods of intense rainfall or rapid snow melt. As is the case with Ms2 debris slides flow channels and deposits in vegetated areas quickly become less visible on airphotos due to the progressively masking effect of vegetation re-growth. These flows are comparable to A1 lahar flows in volcanic terrain.
Geohazard Relations Debris-mud flows are one of the most dangerous of mass movements. They occur suddenly, disrupt rail and highway lines, cover agricultural land and dam rivers in valleys. Ravines are dangerous conduits of failed debris; entrained logs become powerful tools of destruction. Culverts are often unable to convey flows, and distributaries continually shift their course. Activity recurs in inactive debris flows following intense downpours or rapid snowmelt. These meteorological events reactivate mobile debris accumulated in flow channels. In the Canadian Rocky Mountains older vegetated or forested deposits that have a fan stream entrenched along
the entire length of the deposit, and a truncation of the toe by the valley trunk stream are considered “safe sites … because debris flows and high water flows are naturally channellized (sic)”. (Jackson 1987).
References Gerrard AJ (1990) Mountain environments. The MIT Press Cambridge, Mass., p 85 Jackson LE Jr (1987) Debris flow hazard in the Canadian Rocky Mountains. GSC Paper 86–11, p 16
Select Bibliography Campbell RH, Bernknopf RL (1997) Debris-flow hazard map units from gridded probabilities. In: Chen-lung C (ed) First international conference on debris-flow hazards mitigation; mechanics, prediction and assessment. American Society of Civil Engineers, pp 165–175 Coates DR (1990) The relation of subsurface water to downslope movement and failure. In: Higgins CG, Coates DR (eds) Groundwater geomorphology. Geological Society of America Special Paper 252 Corominas J, Remondo J, Farias P, Estevao M, Zézere J, Diaz de Teran J, Dikau R, Schrott L, Moya J, Gonzales A (1996) Debris flow. In: Dikau R, Brunsden D, Schrott L, Ibsen ML (eds) Landslide recognition. John Wiley & Sons, Ltd., Chichester, pp 161–180 Costa JE (1984) Physical geomorphology of debris flows. In: Costa JE, Fleisher PJ (eds) Developments and applications of geomorphology. Springer-Verlag Costa JE, Wieczorek GF (eds) (1987) Debris flows and avalanches: Process, recognition and mitigation, reviews. GSA, Engineering Geology VII Eisbacher GH, Clague JJ (1984) Destructive mass movements in high mountains: Hazard and management. GSC Paper 84–16, pp 15–19 Evans SG (2001) Landslides. In: Brooks GR (ed) A synthesis of geological hazards in Canada. GSC Bull 548:49–51 Jakob M (2005) A size classification for debris flows. Engineering Geology 79:151–161 Jakob M, Hungr O (2005) Debris-flow hazards and related phenomena. Springer-Verlag Jibson RB (1989) Debris flows in southern Puerto Rico. GSA Special Paper 236, pp 29–55 Kienholz H (1977) Kombinierte geomorphologische Gefahrenkarte 1 : 10 000 von Grindelwald. Catena 3:265–94 Kniveton DR, De Graff PJ, Granicas K, Hardy RJ (2000) The development of a remote sensing based technique to predict debris flow triggering conditions in the French Alps. International Journal of Remote Sensing 21(3):419–434 Phien-Wej N, Nutalaya P, Aung Z, Zhibin T (1993) Catastrophic landslides and debris flows in Thailand. Bulletin of Engineering Geology and the Environment 48(1):93–100 Rogers CT (1996) Geo-data system for landslide hazard assessment. In: Housner GW, Chung RM (eds) Natural disaster reduction. Proceedings of ASCE Conference, Washinton, Dec. 3–5, pp 70–71 Schrott L, Buechel S, Gaydos L (1996) Soil flow (mudflow). In: Dikau R, Brunsden D, Schrott L, Ibsen ML (eds) Landslide recognition. John Wiley & Sons, Ltd., Chichester, p 181–187
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Mf3
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Division 4 · Surficial Deposits
Group M · Mass Movement Materials
Fig. Mf3-1. Source. Corominas, et al. (1996) Landslide recognition. Report no 1 of the European Commission Environment Programme. Contract No. EV5V CT94-0454, Identification, Movement and Causes, Richard Dikau et al. (eds) © John Wiley & Sons, Ltd , p 163, fig 7.3 2. Reproduced with permission
Comments. An interpretive block diagram to show the morphological features of a debris-mud flow: A: scarp; B and F: surface of rupture; C: channel of erosion; D: depositional levee from previous debris flow activity; E: deposit.
Fig. Mf3-2.
▼
Mf3 · Debris Mud Flows
Source. Jibson RW (1989) Debris flows in southern Puerto Rico. In: Schultz P, Jibson RW (eds) Landslide processes of the eastern United States and Puerto Rico. Geological Society of America Special Paper 236, fig 27, pp 29-55 Comments. This photo taken in the same area as Fig. Mf3-3 exposes three successively older debris flow deposits in a gully. Distinctive differences in the texture, induration and degree of weathering suggest debris flow recurrence intervals of decades to centuries.
Fig. Mf3-3. Source. Jibson RW (1989) Debris flows in southern Puerto Rico. In: Schultz P, Jibson RW (eds) Landslide processes of the eastern United States and Puerto Rico. Geological Society of America Special Paper 236, pp 29–55, fig 14 Comments. Photo of a debris flow that entrained a house in its path on steep Mc1 colluvium and residuum-covered slopes in Mid-Tertiary limestones. This is one of numerous failures that were triggered by pore-pressure buildup at the colluvium/bedrock contact from the heavy precipitation of a tropical storm in October 1985.
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Division 4 · Surficial Deposits
Group M · Mass Movement Materials
Fig. Mf3-4. Source. LAR, 1975 Comments. Photo of a debris flow on a mountain access road in Mid Jurassic marly shales at Grindelwald in central Switzerland. The flow overtopped wire mesh cribbing which attempted to stabilize the debris of an earlier flow.
The new flow had blocked the roadway, which was cleared shortly before the photo was taken. See also in the same materials slumping in Fig. Ms3-3 and creep in Fig. Mc1-3.
Fig. Mf3-5. Source. LAR Comments. This photo was taken at the mouth of a kilometer long mountain torrent gorge. The torrent intermittently feeds Mf3 debris and Fu1 alluvial fan deposits at a 1 700 m elevation from a gorge head at 2 100 m. Google location is at 08°03'43'' E, 46°35'35'' N in the Swiss Bernese Alps. The torrent is a hanging valley tributary to the U valley of the Lower Grindelwald Glacier at 1 500 m. In June 2005 the 200 m face of the thick deposit collapsed along the full length of its 800 m front. Person is standing on large debris-flow clasts.
Mf3 · Debris Mud Flows
Fig. Mf3-6. Source. LAR, October 1974 Comments. The photo shows masonry check dams arranged in a stacked array of the Gradenbach Torrent at Putschall in the Möll Valley 6.5 km south of Heiligenblut in the Pennine Alps of south central Austria. Torrent reaches in areas of recurrent debris flow activity are most effectively stabilized by such structures. “The rising wings of check dams keep the flow of the torrent to the central axis of the channel and thus prevent lateral and vertical erosion of the unstable bed; aggradation behind check dams adds stability to the toes of embankment slopes on the upstream side; the rush of water is broken by the stepped channel profile, and the gently curved discharge sections of the check dams facilitate unobstructed passage for minor debris floods and flows without endangering the stability of dam abutments”. Eisbacher and Clague (1984) p 26.
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Division 4 · Surficial Deposits
Group M · Mass Movement Materials
Fig. Mf3-7. Source. Diack G (1961) Vancouver Sun Comments. An air view of a debris flow 106 m wide and 30 m deep of January 1961 that cut both the Trans-Canada Highway and the Canadian Pacific Railway in probably glacial till valley fill sediments, in the Fraser River Canyon 195 km northeast of Vancouver, British Columbia. The flow probably originated in Mc1 colluvium (weathered bedrock) in the valley slopes. It was one of seven such road cuts that occurred in southern B.C. caused by torrential downpours with added volumes of melting snow produced by southwesterly warm Chinook (föhn type) winds.
Fig. Mf3-8.
▼
1026
Location. Geographic. 107°17' W, 37°59' N, southwest Colorado, USA Geologic. Tertiary volcanic dome Vertical Airphoto/Image. Type. b/w pan airphoto Scale. 1:35 000 (approx.) Acquisition date. 27 September 1951 Source. Miller VC (1961) Photogeology. McGraw-Hill Book Co. Inc., p 129, fig 9-13 Comments. The stereomodel shows the inactive toe of Slumgullion debris/mudflow cum A1 lahar in the northwest part of the Miocene volcanic San Juan Mountains. The flow is 6 km long and descends 1 900 m, from 3 650 m to 2 750 m from the edge of a basaltic plateau. It is a compound structure, the original flow dates from 700 years ago. 300 years ago an Ms2 debris slide overrode the upper two thirds of the mass. This slide is active, moving at a rate of about 6 m a year. The flow has been the object of detailed investigations and monitoring since 1990; it is now designated as a National Natural Landmark. The flow dammed the Lake Fork of the Gunnison River to form Lake San Cristobal. C, D is bedding of lavas, E are Fu1 alluvial fans, and F is the narrow valley cut by the stream which drains the lake.
Mf3 · Debris Mud Flows
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Division 4 · Surficial Deposits
Fig. Mf3-9. Location. Geographic. 68°03' W, 16°32' S, western Bolivia Geologic. Cordillera Oriental of the central Andes
Group M · Mass Movement Materials
Vertical Airphoto/Image. Type. b/w pan airphoto Scale. 1: 50 000 Acquisition date. 28 November 1956
Mf3 · Debris Mud Flows
Source. Cordova EV (1992) La Fotografia Aerea y su Aplicacion a Estudios Geologicos y Geomorfologicos – Tomo II. Univ. Mayor de San Andres, La Paz, Bolivia, modelo estereoscopico 55 Comments. The stereomodel shows two stabilized debris flows in the valleys of the city of La Paz.
Satellite imagery now shows both deposits to have been built upon and completely urbanized. Urbanization also now completely occupies the beds of the Fv1 braided alluvial streams.
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Division 4 · Surficial Deposits
Fig. Mf3-10. Location. Geographic. Southern Brazil Geologic. Granitic rocks of Brazilian Shield Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 20 000 Acquisition date. 21 January 1953
Group M · Mass Movement Materials
Source. Journal Photo Interprétation, Editions ESKA, Paris, 68-3, 4 Comments. A stereomodel on the east flank of the Serra do Mar Mountains south of Sao Paulo near the coast between Paranagua and Sao José shows a debris flow in a Mc1 deeply weathered zone of granitic rocks in a tropical climate (Np3 descriptor). The dense forest canopy mimics the local topography.
Mf3 · Debris Mud Flows
▼
Fig. Mf3-11.
Location. Geographic. 130°32' W, 57°03' N, northern British Columbia Geologic. Stikinia Superterrane of Intermontane Cordilleran Belt Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 40 000 Acquisition date. Not given Source. Base Mapping and Geomatic Services Branch, Ministry of Sustainable Resources, Government of British Columbia, Canada. BC 5160-024, 025 Comments. The stereomodel shows two 1 km broad deposits of debris from slopes of Triassic andesite that have flowed into the south side of More Creek Valley (elev. ±600 m). The western flow is recent, poorly vegetated, and has partly displaced and blocked the stream channel. The adjacent flow is older, forested with regional subalpine conifers, but with a fresh gully. The source catchments at about 1 800 m are delineated. A smaller, morphologically comparative, Fu1 alluvial fan is at the mouth of a tributary stream east of the flows. The Gf areas are deltaic glaciofluvial deposits from icefield sources in the upper reaches of More Creek. This figure is just east of Fig. Fv1.1-5, and 15 km east of Fig. Ms2-3. ▼
Fig. Mf3-12.
Location. Geographic. 127°53' W, 65°07' N, Northwest Territories Geologic. Mid Cretaceous thrusted sediments of Cordilleran Craton Foreland Belt Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 40 000 Acquisition date. 18 June 1950 Source. Courtesy of Natural Resources Canada, NAPL A 12599-281, 282 Comments. The stereomodel in Loretta Canyon of the Imperial River shows fresh (bright) debris flow deposits on the surfaces of a group of Fu1 alluvial fans. Debris flows are commonly deposited on fans and the latter can include a high proportion of interstartified debris flow materials. Fresh debris flows on fans generally have a surface relief of only a few centimeters to half a meter above the surrounding fan, so are not readily detectable at smaller photo scales. They are then concentrated on the slightly steeper gradient of the headward slopes of the fan cones. Flow source basins have been partly delineated in the model. The bare and forested covers on the flows are unchanged after more than half a century.
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Division 4 · Surficial Deposits
Fig. Mf3-11. (Caption on p. 1031)
Group M · Mass Movement Materials
Mf3 · Debris Mud Flows
Fig. Mf3-12. (Caption on p. 1031)
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Division 4 · Surficial Deposits
Group M · Mass Movement Materials
Mf3 · Debris Mud Flows ▼
Fig. Mf3-13. Location. Geographic. 72°07' W, 18°31' N, southern Haïti Geologic. Greater Antilles Deformed Belt of Caribbean Plate Vertical Airphoto/Image. Type. b/w pan, stereo triplet Scale. 1: 44 000 Acquisition date. 1978 Source. IGN – Photothèque Nationale, France Comments. Three debris flows and their source basins are delineated in this stereomodel of the plaine du Cul de Sac east of Port-au-Prince. They are located on the south slopes of a unit Variant 17.1 graben-like block-faulted depression. A group of older Fu1 and Fu2 alluvial fans are also delineated at the foot of the slopes on the margin of the plain. Morphological distinctions between these deposits are evident between the relatively rough surfaces and steep slopes of the unstratified debris flows and the smoother low slopes of the bedded alluvial fans. An Ms1.1 rock slide occurs on the same regional slope. The Fu2 area, densely cultivated due to favourable groundwater conditions, is a macro scale alluvial fan occasionally termed a piedmont apron.
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Mf4
Division 4 · Surficial Deposits
Mf4 Mountain Valley Natural Dams Characterization Lakes dammed by landslides, late neoglacial moraines and glaciers in mountain regions, drain suddenly triggered by tectonic or climatic forces to produce floods that are orders of magnitude larger than normal streamflows. The floods may transform into Mf3 debris flows as they travel down steep valleys. Variants are based on the most unstable materials that form the dams which can be polygenetic. Overtopping is the most common cause of failure.
Geohazard Relations Natural dams may cause upstream flooding in a valley as the lake rises. The large discharges and long travel distances of outburst floods and debris flows cause widespread destruction and loss of life in downvalley settlements and developments. Global warming is increasing the frequency and hazardous effects of these types of failures in the alpine areas of North America, the Himalayas and the Andes.
Select Bibliography Clague JJ, Evans SG (1994) Formation and failure of natural dams in the Canadian Cordillera. GSC Bull 464 Costa JE, Schuster RL (1988) The formation and failure of natural dams. GSA Bull 100:1054–1068 Fort M (2006) Ephemeral natural dams in the Nepal Himalayas: Types, geomorphic impacts and risk induced. Geophysical Research Abstracts, vol 8, no 06904. Huber UM, Bugmann HK, Reasoner MA (2005) Global change and mountain regions: An overview of current knowledge. Springer-Verlag Kattelmann R (2003) Glacial lake outburst floods in the Nepal Himalaya: A manageable hazard? Natural Hazards 28(1):145–154
Mf4.1
Mf4.1 Landslide Dams Characterization Landslide dams form generally in two geomorphic settings: steep narrow mountain valleys broad open valleys and lowlands where rivers have incised in marine or lacustrine sediments A lake is formed by the damming of a valley by deposits of geounits Ms1, rock slides; Mv2 rock avalanches; Ms3
Group M · Mass Movement Materials
rock slumps; Mf3 debris-mud flows, and Mf1 rotational slides in unconsolidated sediments. The common processes causing these slope failures are excessive precipitation – rainfall and snowmelt, and earthquakes. The dams fail by overtopping and breaching.
Geohazard Relations Dams along small streams of small watersheds in mountainous terrain are relatively stable. Those blocking larger rivers can fail with catastrophic secondary effects. Dams impounding rivers upstream in lowlands filled with fine Quaternary sediments will be overtopped within a few days. Subsequent incision of the dam debris further reduces the level of impounded waters. Dams consisting of blocks of competent bedrock (e.g., from Ms1 slides, Mv2 avalanches, and Ms3 slumps) tend to be stable “because any overflowing water is incapable of eroding the coarse materials and because the dam slopes are unlikely to fail. In any case, these latter dams are so porous and permeable that there commonly is little or no overflow.” (Clague and Evans 1994). Rafted blocks of dam material can bury the valley bottom downstream, and high water turbidity pollute water supplies to farms and communities downstream for several days after river flow is restored.
Reference Clague JJ, Evans SG (1994) Formation and failure of natural dams in the Canadian Cordillera. GSC Bull 464:4–13
Select Bibliography Casagli N, Ermini L (1999) Geomorphic analysis of landslide dams in the Northern Appennine. Transactions Japanese Geomorphological Union 20(3):219–249 Costa JE, Schuster RL (1988) The formation and failure of natural dams. GSA Bull 100:1055–1060 Evans SG (1986) Landslide damming in the Cordillera of western Canada. Landslide dams; processes, risk, and mitigation. ASCE, Geotechnical Special Publication no 3, pp 111–130 King J, Loveday I, Schuster Rl (1989) The 1985 Bairaman landslide dam and resulting debris flow, Papua New Guinea. Quarterly Journal of Engineering Geology and Hydrogeology 22(4): 157–270 Korop O, Tweed FS (2007) Ice, moraine and landslide dams in mountainous terrain. Quaternary Science Reviews 26:3406–3422 Schuster RL, Costa JE (1986) A perspective on landslide dams. Landslide dams; processes, risk, and mitigation. ASCE, Geotechnical Special Publication no 3, pp 1–20
Mf4.1 · Landslide Dams
Location. Geographic. 122° W, 49°46' N (approx.), southern British Columbia Source. Courtesy of Natural Resources Canada, GSC 204047C Comments. The air perspective view shows a landslide dam formed by Mv2 rock avalanche debris in the vicinity of Mt. Mason in the southern Coast Mountains. The debris fill down-valley is spillout from the avalanche deposit; it is unrelated to the valley slopes. On 12 May 2008 a 7.9 Richter earthquake occurred in the Kunlun Mountains near the thrust-faulted western edge of the Sichuan basin in southern China. the event caused 34 landslide dams along faults in the mountains. Most collapsed by overtopping. These and thousands of associated other slope failures resulted in the deaths of 69 000 people, injury to 370 000 and left 5 000 000 homeless.
Fig. Mf4.1-2.
▼
Fig. Mf4.1-1.
Location. Geographic. 78°45' E, 31°50' N (approx.), Zaskar Mountains, southwest Tibet Geologic. Himalaya tectogenic belt Vertical Airphoto/Image. Type. ASTER, 15 m resolution Acquisition date. 01 October 2003/15 July 2004 Source. NASA – ASTER instrument team Comments. These comparative images acquired nine and a half months apart show a lake created by a landslide dam on the Pareechu River in Tibet, a tributary of the Sutlej River in India. The height of the dam is 35 m, the created lake is 6 000 m long by 1 500 m wide and the rate of rise in the water level is 0.5 m per day. Authorities in both countries had evacuated inhabitants from downstream villages as a precautionary measure.
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Division 4 · Surficial Deposits
Fig. Mf4.1-2. (Caption on p. 1037)
Group M · Mass Movement Materials
Mf4.1 · Landslide Dams
Fig. Mf4.1-3. Location. Geographic. 130°58' W, 61°24' N, southern Yukon Territory Vertical Airphoto/Image. Type. b/w pan airphoto Scale. 1: 20 000 Acquisition date. Not given
Source. Jackson LE (1994) Terrain inventory and Quaternary history of the Pelly River Area, Yukon Territory. GSC Memoir 437, p 37, fig 37 Comments. The stereomodel pictures a landslide of Upper Triassic S1 conglomeratic rocks damming a lake in the Campbell Range of the Pelly Mountains.
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Fig. Mf4.1-4. (Caption on p.1042)
Group M · Mass Movement Materials
Mf4.1 · Landslide Dams
Fig. Mf4.1-5. (Caption on p. 1042)
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Division 4 · Surficial Deposits ▼
Fig. Mf4.1-4. Location. Geographic. 127°15' W, 62°25' N, Northwest Territories Geologic. Eastern Omineca Cordilleran Belt, Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 60 000 Acquisition date. Not given Source. Courtesy of Natural Resources Canada, NAPL A 18044-51, 52 Comments. Multiple dam deposits are delineated in this stereomodel of Avalanche Lake in the Devonian miogeoclinal (a prograding wedge of shallow-water sediment at the continental margin) Backbone Ranges of the Mackenzie Mountains. They resulted from Ms1 rock slides along bedding planes of south-dipping (30°) dolomite delineated on the slopes surrounding the lake. The main failure occurred where the cliff collapsed on the north side of the valley and surged up the south wall. See also Fig. Mv2-3.
▼
Fig. Mf4.1-5.
Location. Geographic. 133°40' W, 59°06' N, northwest British Columbia Geologic. Cache Creek Terrane of the Intermontane Cordilleran Belt Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 70 000 Acquisition date. Not given Source. Courtesy of Natural Resources Canada, NAPL A 25825-23, 24 Comments. A stereomodel in the Tagish Highland of the Yukon Plateau shows 12 km long Sloko Lake elevation 900 m and its outlet stream that carry the meltwaters of the Llewellyn Glacier and icefield to the Taku River. The landslide dam, which is 2 100 m wide, evidently consists of blocks of Eocene acidic and basic volcanic rocks and could be considered a large A1 lahar flow. As the Variant description explains, such dams tend to be stable due to the inability of overflowing water to erode the coarse material as well as to its porosity and permeability. The slide mass is holding the lake up, but a limited drainage is sustained around the toe of the slide. Increased meltwater discharge that would accompany recession of the Llewellyn Glacier due to climate warming could result in a sudden overtopping of the dam. A probable Ms2 debris slide is delineated on the east side of the dam slide.
Group M · Mass Movement Materials
Mf4.2 · Moraine Dams
Mf4.2 Moraine Dams Characterization Since the end of the nineteenth century many Gl5 mountain valley glaciers have retreated significantly, leaving behind many lakes dammed by their end moraines. The drainage area of moraine damsites is much smaller than that of Mf4.1 landslide dam sites. Moraine dams are commonly overtopped and breached by waves generated by the impact of an icefall from a crevassed glacier or a rockfall from the steep slopes above the lake. Overtopping can also result from increased stream-flow during periods of rapid glacier retreat, intense rainfall or snowmelt. Moraines with ice cores or intersticial ice are becoming susceptible to failure during a period of climatic warming.
Select Bibliography Clague JJ, Evans SG (1994) Formation and failure of natural dams in the Canadian Cordillera. GSC Bull 464:13–18 Clague JJ, Evans SG (2000) A review of catastrophic drainage of moraine-dammed lakes in British Columbia. Quaternary Science Reviews 19(17) Costa JE, Schuster RL (1988) The formation and failure of natural dams. GSA Bull 100:1063–1065 Dahms SH (2006) Moraine dam failure and glacial lake outburst floods. Quaternary Geology ES 767, Emporia State University Häusler, Payer T, Leber D, Brauner M, Wangda D, Rank D, Papesch W (2007) Hazard potential of seepages causing moraine dam break in the Bhutan Himalayas. Geophysical Research Abstracts 9(04048) Ryder JM (1998) Geomorphological processes in the alpine areas of Canada. GSC Bull 524:34–35
Geohazard Relations Water floods or debris flows downvalley can be catastrophic. “Debris flows from breached morainal dams have caused enormous damage in the mountains of north-central Peru – on 13 March 1941, Laguna Kohup in the Cordillera Blanca drained rapidly to produce a debris flow which erased a major section of the town of Huaraz, killing several thousand people.” (Eisbacher and Clague 1984).
Reference Eisbacher GH, Clague J (1984) Destructive mass movements in high mountains: Hazard and management. GSC Paper 84–16, p 46
Fig. Mf4.2-1. Source. Eisbacher GH, Clague JJ (1984) Destructive mass movements in high mountains: Hazard and management. GSC Paper 84-16, p 44, fig 33 Comments. Diagram shows a moraine damming a depression filled with meltwater from a glacier.
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Group M · Mass Movement Materials
Fig. Mf4.2-2. Source. Post A, LaChapelle ER (1971) Glacier ice. University of Toronto Press, p 29, photo 35. Reprinted by permission of the University of Washington Press Comments. Photo of a moraine dammed lake below the snout of the retreated Pattullo Glacier circa 1970 in the Mt. Pattullo Massif of the northern Coast Mountains of British Columbia, Canada at 129°45' W, 56°14' N.
Mf4.2 · Moraine Dams
Fig. Mf4.2-3. Source. Clague JJ, Evans SG (1994) Formation and failure of natural dams in the Canadian Cordillera. GSC Bulletin 464, cover illustration Comments. Air view to southwest of August 1984 shows a breached moraine dam at 124°24' W, 51°12' N in the Coast Mountains of southern British Columbia, Canada. The moraine had been deposited by Cumberland Glacier (in shadow) in the upper left of the photo. The glacier has since receded to a cliff above Nostetuko Lake. On 19 July 1983 part of the toe of the glacier broke away and cascaded into the lake. Waves generated by the impact of the icefall overtopped and rapidly incised the moraine to a depth of almost 40 m, suddenly releasing 6 × 106 m3 of water producing a destructive flood that swept 115 km downstream, stripping large tracts of forest and sediments from the valley floor. The eroded material is seen deposited as a large fan directly downstream from the dam.
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Group M · Mass Movement Materials
Mf4.2 · Moraine Dams ▼
Fig. Mf4.2-4.
Vertical Airphoto/Image. Type. Normal colour airphoto Scale. 1: 20 000 Acquisition date. 19 May 1977 Source. Die Schweiz und ihre Gletscher, 2nd edn. Schweizerische Verkehrszentrale, Zürich, Kümmerly+Frey, Bern, p 115, photo 15 Comments. The photo shows a moraine from one glacier damming the lake in the valley of a neighbouring glacier at 09°52' E, 46°24' N. The westerly moraine of Tschierva Glacier dams the lake below Roseg Glacier, 12 km up-valley from Pontresina, Graubünden, southeast Switzerland. An outlet stream from the lake has eroded a small breach at the north end of the blocking moraine. Subsequent satellite imaging monitored the status of the lake. Additional details visible in the photo are a geostructure Unit 18 geolineament which parallels the east side of Roseg Glacier; and a Zm2 rock glacier in a cirque on the rock ridge dividing the glaciers.
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Division 4 · Surficial Deposits
Mf4.3 Glacier Dams Characterization
Group M · Mass Movement Materials
“In rugged terrain glacier outburst floods can transform into rapidly moving debris flows (Mf3) if loose morainal or colluvial debris adjacent to the stream channel is incorporated into the floodwater.” (Ryder 1998, p 32).
Gl5 glaciers impound water in ice-free valleys. Meltwaters flow along crevasses and cavities at the base of the glacier to form interconnected tunnels. The flows melt the ice and enlarge the tunnel system. The process continues until the weakened ice dam can no longer support the water behind it and collapses.
References
Geohazard Relations
Ageta Y, Iwata S, Yabuki H, Naito N, Sakai A, Narama C, Karma (2000) Expansion of glacier lakes in recent decades in the Bhutan Himalayas. Debris-Covered Glaciers. IAHS Publication, pp 165–175 Costa JE, Schuster RL (1988) The formation and failure of natural dams. GSA Bull 100:1060–1063 Eisbacher GH, Clague JJ (1984) Destructive mass movements in high mountains: Hazard and management. GSC Paper 84–16, pp 45–46 Huggel C, Kääb C, Haeberli W, Teysseire P, Paul F (2002) Satellite and aerial imagery for analysing high mountain lake hazards. Canadian Geotechnical Journal 39(2):316–330 Iturrizaga L (2005) New observations on present and prehistorical glacier-dammed lakes in the Shimshal Valley (Karakoram Mountains). Journal of Asian Earth Sciences 25(4):545–555 Liestol O (1956) Glacier-dammed lakes in Norway. Norsk Geografisk Tiddskrift 15:122–149 Quincy DJ, Richardson SD, Luckman A, Lucas RM, Reynolds JM, Hambrey MJ, Glasser NF (2007) Early recognition of glacial lake hazards in the Himalaya using remote sensing data sets. Global and Planatary Change 56(1–2):137–152
The greatest potential hazard exists “as glacier recession occurs in accordance with climate warming. Drainage will occur for the first time at lakes that have not previously drained, releasing catastrophic flood discharges down valleys” (Ryder 1998, p 32), e.g., lake G in Fig. Mf4.3-1 in a trunk valley. Additionally, as shown in Fig. Mf4.3-2, the impounded waters resulting from a glacier surge across a mountain valley could inundate upstream settlements and transportation corridors. Clague estimates that there have been about 30 000 deaths from glacier-related catastrophes in the last 150 years. Ice dams prone to catastrophic leakage are often referred to by the Icelandic term jokulhlaup.
Fig. Mf4.3-1. Source. Costa JE, Schuster RL (1988) The formation and failure of natural dams. Geological Society of America Bulletin vol 100, fig 9 Comments. Sketch map showing the geomorphic settings and classification of icedammed lakes. Lake G in the trunk valley is potentially the most hazardous for a downstream flood (to the right) by a failure of the tributary glacier.
Clague JJ, Evans SG (1994) Formation and failure of natural dams in the Canadian Cordillera. GSC Bull 464:18–28 Ryder JM (1998) Geomorphological processes in the alpine areas of Canada. GSC Bull 524:31–32
Select Bibliography
Mf4.3 · Glacier Dams
Fig. Mf4.3-2. Location. Geographic. 137°59' W, 60°17' N, southwest Yukon Territory Source. ClagueJJ, Evans SG (1994) GSC Bull. 464, p 24, fig 28 Comments. Map showing the extent of a lake that inundated valleys during the late Holocene up to 95 km upstream from a glacier advance across the valley in the St. Elias Mountains
If Lowell Glacier were to surge about 1 km, the lake would reform and might inundate the town of Haines Junction and sections of the Alaska Highway upstream. The inset frame locates the coverage of vertical airphoto 176 of the stereopair Fig. Mf4.3-5 of the tongue of Lowell Glacier.
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Fig. Mf4.3-3. Location. Geographic. 74°15' W, 71°35' N, northeast Baffin Island, Nunavut Source. Courtesy of Natural Resources Canada, NAPL RR325, 3193, 14 September 1953 Comments. Air view to southeast of a 8 km long by 2 km broad unnamed Gl4 outlet glacier damming the upper end
Group M · Mass Movement Materials
of Drever Arm Fjord in Buchan Gulf at the upper right of the photo. Icebergs are calving both into the dammed arm and northward towards Baffin Bay on the left. The icefield at the top of the photo is at 1 100 m elevation, the icefield source of the glacier is at 1 265 m. The moraine combines that from a coalescing glacier 4 km upstream. A meltwater spillway is at the contact of the glacier toe with the rockslope. The glacier’s recession has since opened up half the width of Drever Arm.
Mf4.3 · Glacier Dams
Fig. Mf4.3-4.
Fig. Mf4.3-5.
▼
Location. Geographic. 133°50' W, 58°49' N, northern Coast Mountains, British Columbia Source. Post A, LaChapelle ER (1971) Glacier ice. University of Toronto Press, p 85, photo 103. Reprinted by permission of the University of Washington Press Comments. The air perspective photo is a view southwest of 4 km long Lake Tulsequah. The lake is in a tributary valley of the Tulsequah Glacier Valley and is dammed by a short lobe of that glacier. The lake is effectively dammed by glaciers at both ends, the other is behind the mountain shoulder in the center, at the south end of the lake.
Location. Geographic. 137°59' W, 60°17' N, southwest Yukon Geologic. Alexander Superterrane of the Insular Cordilleran Belt Vertical Airphoto/Image. Type. b/w pan, stereo pair Scale. 1: 40 000 Acquisition date. 14 June 1948 Source. Courtesy of Natural Resources Canada, NAPL A 11521-175, 176 Comments. This stereomodel shows the 6 km broad terminus of Gl5 Lowell Glacier in Ordovician carbonates of
the St. Elias Mountains on 14 June 1948 at the channels of the south-flowing (to bottom) Alsek River Valley. At the date of photography the glacier was in recession and there is a temporary lake (with a few bergs) partly held up by Gf3.2a glaciofluvial valley fill deposits through which the river runs. The glacier’s lateral moraines (see Gl5) are coded Gt4.1. If the lower moraine had reached the other side of the valley the site would have been a Mf4.2 moraine dam variant. The potential for upstream flooding in the Alsek Valley is described in Fig. Mf4.3-2. The St. Elias Mountains contain the largest non-polar icefield on Earth.
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Fig. Mf4.3-5. (Caption on p. 1051)
Group M · Mass Movement Materials
A Appendix Abbreviations and Acronyms
AAPG AAG AGFG ap ASCE ASTER ATM AVHRR BC BGRG BRGM b/w CAN CCRS CEOS CGS CIR CNES CNRS COSPAR CRREL CSPG CSIRO DEM EDC EIA EO EOSAT ERS esa ESPON
American Association of Petroleum Geologists Association of American Geographers American Geomorphology Field Group air photograph American Society of Civil Engineers Advanced Spaceborne Thermal Emission and Reflection Radiometer Advanced Thematic Mapper Advanced Very High Resolution Radiometer MAPS – BC, British Columbia British Geomorphological Research Group Bureau de Recherches Géologiques et Minières (France) black and white Canada Canada Center for Remote Sensing Committee on Earth Observation Satellites (esa) Canadian Geotechnical Society colour infrared Centre National d’Études Spatiales (France) Centre National de la Recherche Scientifique Committee on Space research (of ICSU) Cold Regions Research and Engineering Laboratory (U.S. Army) Canadian Society of Petroleum Geologists Commonwealth Scientific and Industrial Research Organization (Australia) Digital Elevation Model Eros Data Center Environmental impact assessment Earth Observation Earth Observation Satellite Company European Remote Sensing Satellite European Space Agency European Spatial Planning Observation Network
FAO
Food and Agriculture Organization of the United Nations fcc False colour composite FR France GIS Geographic Information System GSA Geological Society of America GSC Geological Survey of Canada GSFC Goddard Space Flight Center HIRIS High Resolution Imaging Spectrometer IAEG International Association of Engineering Geology IAHS International Association of Hydrological Sciences IAS International Association of Sedimentologists IBG Institute of British Geographers IGCP International Geological Correlation Programme IGN Institut Géographique National (France) IGS Institute of Geological Sciences IGU International Geographical Union IKONOS Earth observation satellite INQUA International Quaternary Assciation InSAR Interferometric Synthetic Aperture Radar ISPRS International society for Photogrammetry and Remote Sensing ISRM International Society for Rock Mechanics ISSS International Society of Soil Science ITC International Institute for Aerospace Survey and Earth Sciences JPL Jet Propulsion Laboratory LAR Lambert Alfred Rivard LFC Large Format Camera MDA Earth Sat MDA Federal Inc. mono monoscopic MSS Multispectral Scanner NAPL National Air Photo Library (Canada) NAS National Academy of Sciences NASA National Aeronautics and Space Administration (USA) NOAA National Oceanic and Atmospheric Administration (USA)
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Appendix · Abbreviations and Acronyms
NRC NTIS ORSTOM pan RADAR RBV RGS RMS SAR SCS SIR-A, B, C SLAR
National Research Council (Canada) National Technical Information Service (USA) Office de la Recherche Scientifique et Technique Outre-Mer (France) panchromatic Radio detection and ranging Return Beam Vidicon Camera System Royal Geographical Society Rock mass strength Synthetic aperture radar Soil Conservation Service (USA) Shuttle Imaging Radar Side-looking airborne Radar
SPOT TM TOMS TRB UNDP UNEP USAF USDA USGS VEI vert
Satellite Pour l’Observation de la Terre Thematic Mapper Total ozone mapping spectrometer Transportation Research Board, National Academy (of Sciences) (USA) United Nations Development Programme United Nations Environment Programme United States Air Force United States Department of Agriculture United States Geological Survey Volcano explosivity index vertical
