From the Shield to the Sea: Geological Field Trips from the 2011 Joint Meeting of the GSA Northeastern and North-Central Sections edited by Richard M. Ruffolo and Charles N. Ciampaglio
Field Guide 20 THE GEOLOGICAL SOCIETY OF AMERICA®
From the Shield to the Sea: Geological Field Trips from the 2011 Joint Meeting of the GSA Northeastern and North-Central Sections
edited by
Richard M. Ruffolo GAI Consultants, Inc. Pittsburgh Office 385 East Waterfront Drive Homestead, Pennsylvania 15120-5005 USA Charles N. Ciampaglio Wright State University–Lake Campus 7600 Lake Campus Drive Celina, Ohio 45822 USA
Field Guide 20 3300 Penrose Place, P.O. Box 9140
Boulder, Colorado 80301-9140, USA
2011
Copyright © 2011, The Geological Society of America (GSA), Inc. All rights reserved. GSA grants permission to individual scientists to make unlimited photocopies of one or more items from this volume for noncommercial purposes advancing science or education, including classroom use. In addition, an author has the right to use his or her article or a portion of the article in a thesis or dissertation without requesting permission from GSA, provided the bibliographic citation and the GSA copyright credit line are given on the appropriate pages. For permission to make photocopies of any item in this volume for other noncommercial, nonprofit purposes, contact The Geological Society of America. Written permission is required from GSA for all other forms of capture or reproduction of any item in the volume including, but not limited to, all types of electronic or digital scanning or other digital or manual transformation of articles or any portion thereof, such as abstracts, into computer-readable and/ or transmittable form for personal or corporate use, either noncommercial or commercial, for-profit or otherwise. Send permission requests to GSA Copyright Permissions, 3300 Penrose Place, P.O. Box 9140, Boulder, Colorado 80301-9140, USA. GSA provides this and other forums for the presentation of diverse opinions and positions by scientists worldwide, regardless of their race, citizenship, gender, religion, sexual orientation, or political viewpoint. Opinions presented in this publication do not reflect official positions of the Society. Copyright is not claimed on any material prepared wholly by government employees within the scope of their employment. Published by The Geological Society of America, Inc. 3300 Penrose Place, P.O. Box 9140, Boulder, Colorado 80301-9140, USA www.geosociety.org Printed in U.S.A. Cataloging-in-Publication data for this volume is available from the Library of Congress. ISBN: 9780813700205 Cover, front: Fifteen-foot-high foreset beds, overlain by thin, dark-brown topset bed in a kame delta near West Liberty, Butler County, Pennsylvania. The topset-foreset sequence is the lower of two sets exposed vertically in the exposure. The other set is on the bench above the topset bed. The delta was deposited in an ice-dammed, pro-glacial lake at the end of the Jacksville Esker. The exposure in the Glacial Sand and Gravel Co. Mine 31 is part of Stop 1 of Field Trip 5 (see Fleeger, G.M., et al., “Quaternary geology of northwestern Pennsylvania,” p. 87). Bill Bragonier (formerly of the Pennsylvania Geological Survey; currently with Rosebud Mining Co.) for scale (6′ 4″; 1.98 m). Photograph by Gary M. Fleeger, Pennsylvania Geological Survey, July 2009. Back: Group examining a Late Devonian paleontological site in the Catskill Formation along Interstate 99 in Lycoming County, Pennsylvania. (Field Trip 1; see Daeschler, E.B., and Cressler, W.L., III, “Late Devonian paleontology and paleoenvironments at Red Hill and other fossil sites in the Catskill Formation of north-central Pennsylvania,” p. 1.) Photo by Fred Mullison, Academy of Natural Sciences, Philadelphia.
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Contents
Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v 1. Late Devonian paleontology and paleoenvironments at Red Hill and other fossil sites in the Catskill Formation of north-central Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 Edward B. Daeschler and Walter L. Cressler III 2. An introduction to structures and stratigraphy in the proximal portion of the Middle Devonian Marcellus and Burket/Geneseo black shales in the Central Appalachian Valley and Ridge . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 Terry Engelder, Rudy Slingerland, Michael Arthur, Gary Lash, Daniel Kohl, and D.P. Gold 3. Pennsylvanian climatic events and their congruent biotic responses in the central Appalachian Basin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45 David K. Brezinski and Albert D. Kollar 4. Landslides in the vicinity of Pittsburgh, Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61 Richard E. Gray, James V. Hamel, and William R. Adams Jr. 5. Quaternary geology of northwestern Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87 Gary M. Fleeger, Todd Grote, Eric Straffin, and John P. Szabo 6. The history and geology of the Allegheny Portage Railroad, Blair and Cambria Counties, Pennsylvania . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111 John A. Harper 7. Early industrial geology of western Pennsylvania and eastern Ohio: Early gristmills and iron furnaces west of the Alleghenies and their geologic contexts . . . . . . . . . . . . . . . . . . . . . . . . 143 Joseph T. Hannibal, Tammie L. Gerke, Mary K. McGuire, Harry M. Edenborn, Ann L. Holstein, and David Parker 8. The old, the crude, and the muddy: Oil history in western Pennsylvania . . . . . . . . . . . . . . . . . . 169 Kristin M. Carter and Kathy J. Flaherty
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Preface From the Shield to the Sea features field guides and descriptions of eight of the geological field trips offered during the Joint Meeting of the Geological Society of America (GSA) Northeastern and NorthCentral Sections held in Pittsburgh, Pennsylvania, in March 2011. The trips described herein are not only timely and topical, but also highlight the region’s geology from eastern Ohio to the Central Appalachian Valley and Ridge. The regional geology and forces that have shaped the topography of the area are highlighted by examining landslides (Gray et al.), glacial sedimentation and stratigraphy (Fleeger et al.), and examination of the structure and stratigraphy of the prevalent Middle Devonian black shales (Engelder et al.). The geologic history of the area from a biotic perspective are covered by Daeschler and Cressler with the examination of sites that illustrate the evolution of early terrestrial vertebrates and terrestrial ecosystems from the Upper Devonian Catskill Formation, and Brezinski and Kollar’s examination of how Pennsylvanian climate changes impacted the biota of the region. In addition, three of the trip descriptions illustrate how regional geology has helped shape the industrial history of our region: Carter and Flaherty examine western Pennsylvania’s rich history of oil and gas exploration; Harper provides an opportunity to see the immense effort needed to take the Pennsylvania Mainline Canal system over the imposing Allegheny front; and Hannibal et al.’s trip visits early gristmills and iron furnaces. The editors would like to thank all the authors, trip leaders, and organizers for their hard work and time devoted to this guidebook. Special thanks to all the reviewers who helped improve the field guide. We would also like to thank the staff in the GSA Publications Department for their tremendous job of guiding us through the production process. The editors hope readers will enjoy this field guide and find its contents valuable. Richard M. Ruffolo and Charles N. Ciampaglio
The Geological Society of America Field Guide 20 2011
Late Devonian paleontology and paleoenvironments at Red Hill and other fossil sites in the Catskill Formation of north-central Pennsylvania Edward B. Daeschler Vertebrate Paleontology, Academy of Natural Sciences, 1900 Benjamin Franklin Parkway, Philadelphia, Pennsylvania 19103, USA Walter L. Cressler III Francis Harvey Green Library, 25 West Rosedale Avenue, West Chester University, West Chester, Pennsylvania 19383, USA
ABSTRACT The stratified red beds of the Catskill Formation are conspicuous in road cut exposures on the Allegheny Plateau of north-central Pennsylvania. During this field trip we will visit and explore several fossil localities within the Catskill Formation. These sites have been central to recent investigations into the nature of Late Devonian continental ecosystems. By the Late Devonian, forests were widespread within seasonally wellwatered depositional basins and the spread of plants on land from the late Silurian through the Devonian set the stage for the radiation of animals in both freshwater and terrestrial settings. A diverse assemblage of flora and fauna has been recovered from the Catskill Formation including progymnosperms, lycopsids, spermatophytes, zygopterid and stauripterid ferns, barinophytes, invertebrates and invertebrate traces, and vertebrates such as placoderms, acanthodians, chondrichthyans, actinopterygians, and a variety of sarcopterygians including early tetrapods. Since the early 1990s, highway construction projects along the Route 15 (Interstate 99) have provided a new opportunity for exploration of the Catskill Formation in Lycoming and Tioga counties. The faunas along Route 15 are dominated by Bothriolepis sp. and Holoptychius sp. and also include Sauripterus taylori and an assortment of other interesting records. The most productive Catskill site, and the source of early tetrapod remains, is Red Hill in Clinton County. Red Hill presents a diverse and unique flora and fauna that is distinct from Route 15 sites, and also provides a spectacular section of the alluvial plain deposits of the Duncannon Member of the Catskill Formation.
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[email protected];
[email protected] Daeschler, E.B., and Cressler, W.L., III, 2011, Late Devonian paleontology and paleoenvironments at Red Hill and other fossil sites in the Catskill Formation of north-central Pennsylvania, in Ruffolo, R.M., and Ciampaglio, C.N., eds., From the Shield to the Sea: Geological Field Trips from the 2011 Joint Meeting of the GSA Northeastern and North-Central Sections: Geological Society of America Field Guide 20, p. 1–16, doi: 10.1130/2011.0020(01). For permission to copy, contact
[email protected]. ©2011 The Geological Society of America. All rights reserved.
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OVERVIEW The earliest paleontological investigations of the Catskill Formation in Pennsylvania date to the 1830s and 1840s, when James Hall described the pectoral fin of the rhizodontid sarcopterygian Sauripterus taylori from a fossil discovered during construction of a railroad line near Blossburg, Tioga County (Hall, 1843). Charles Lyell passed through Blossburg in 1840 and examined the Catskill Formation during one of his two North American tours (Leviton and Aldrich, 1992; Davis et al., 2004). Additional fossil material from the Upper Devonian red beds of Pennsylvania was described by Leidy, Newberry, and Eastman during the nineteenth century and early twentieth century. During the 1960s, Keith S. Thomson described the tristichopterid sarcopterygian Hyneria lindae (Thomson, 1968) from material found in the vicinity of North Bend, Clinton County, and Sterropterygion brandei (Thomson, 1972; Rackoff, 1980) from Tioga County. Thomson became aware of Catskill Formation localities from Donald Baird and Alfred Sherwood Romer of Harvard University who had done prospecting and collecting in the region during the 1950s. Paleobotanical investigations in the Catskill Formation began with Leo Lesquereux, who described two species of Archaeopteris from Meshoppen, Wyoming County (Lesquereux, 1884) in his pioneering report on Pennsylvania’s coal flora for the state’s Second Geological Survey. Chester Arnold figured and further described these specimens (Arnold, 1936), as well as other plants from the Oswayo Formation in northern Pennsylvania (Arnold, 1939), a lateral marine equivalent of the Catskill. The most productive sites in this unit were near Port Allegany in McKean County, and when John Pettitt and Charles Beck reinvestigated Arnold’s material, they were able to describe the first confirmed seed from the Late Devonian, Archaeosperma arnol-
dii (Pettitt and Beck, 1968). Recent paleobiological investigations into the Catskill Formation were initiated in 1993 as field crews from the Academy of Natural Sciences of Philadelphia– University of Pennsylvania began systematic exploration of exposures of the Catskill Formation principally in Clinton, Lycoming, and Tioga Counties. Natural, unweathered exposures of the Catskill Formation are rare in Pennsylvania, so paleontological investigations have been closely linked with the construction of the railway system in the nineteenth century and the highway system in the twentieth and twenty-first centuries. We are indebted to the Pennsylvania Department of Transportation and its contractors for access to the sites where most of our fossil discoveries have been made. The Catskill Formation is composed of sand, silt, and mud deposited in a series of prograding deltas, known as the Catskill Delta Complex (Sevon, 1985) (Fig. 1). This clastic wedge was derived from the middle to late Devonian Acadian Mountains shedding sediment westward and northwestward toward a shallow epicontinental sea in the foreland basin of the orogenic zone (Faill, 1985). The Acadian Orogeny was part of the Middle to Late Paleozoic assembly of the Euramerican landmass (a.k.a. Laurussia or the Old Red Sandstone Continent) and subsequent assembly of the supercontinent Pangea. The deposits of the Catskill Delta Complex grade upward from basinal black shales to nearshore marine facies through transitional facies and into delta plain and alluvial plain depositional settings. Our paleontological studies have focused on the deltaic and alluvial plain facies at the top of the Catskill Formation. Palynological analysis has placed all but one of the productive field sites visited on this trip within the Fa2c part of the Fammenian Stage (Traverse, 2003). This corresponds to the poorly calibrated VH palynozone and is perhaps less ambiguously attributed to the
Figure 1. Block diagram of depositional systems of the Catskill Delta Complex during the Late Devonian in Pennsylvania. Reprinted from Cressler et al. (2010a).
Red Hill and other fossil sites in the Catskill Formation VCO palynozone (sensu Streel et al., 1987). The Tioga Welcome Center locality in Tioga County (Stop 4) is slightly older. Where differentiated, the uppermost subdivisions of the Catskill Formation are the Sherman Creek Member and the overlying Duncannon Member (Fig. 2). At Powys Curve (Stop 1) in Lycoming County, the Sherman Creek Member is well exposed. The Sherman Creek Member is typically composed of fining-upward cycles on the order of two to three meters thick. These cycles are often laterally continuous and are dominated by fine to medium sandstones and siltstones. Poorly developed paleosols and root traces are seen in the fine sandstones and siltstones in the upper part of each cycle (Harvey, 1998). The lithology suggests that the Sherman Creek Member formed in a delta plain setting characterized by low-gradient, high-sinuosity, shallow channels near the coastline (Sevon, 1985). In contrast, the Duncannon Member generally consists of 5–10-m-thick fining-upward cycles dominated by thick, crossbedded, basal sandstones. The contact between the channel sandstone and the mudstone at the top of the underlying cycle is sharp and irregular. Mature paleosols and root traces are often recognized in the mudstones. The Duncannon Member formed in meandering stream channels and overbank deposition on an alluvial plain and is very well exposed at Red Hill (Stop 5), the source of abundant fossil material including plants, arthropods, and a diverse vertebrate fauna including early tetrapods. As recorded in the rocks observed on this field trip, the Late Devonian was a time of major transitions in flora, fauna, and the geobiological system. By the Late Devonian, forests were widespread within the seasonally well-watered depositional basins.
Figure 2. Stratigraphic relationships of the Catskill Formation in north-central Pennsylvania.
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The dominant tree was the progymnosperm Archaeopteris, growing up to 18 m tall. This was the first plant known with a bifacial cambium as in modern wood, but it reproduced through spores (Meyer-Berthaud et al., 1999). Seed plants are first known from the Late Devonian (Rothwell, et al., 1989). Evidence at Red Hill indicates that opportunistic seed plants, growing in areas disturbed by fire, took advantage of the destruction of the widespread fern Rhacophyton (Cressler, 2006; Cressler et al., 2010a). Lycopsids were important swamp plants in the Late Devonian, attaining the stature of small trees and, along with Rhacophyton, contributing to the thin coal seams known from this time. These small Late Devonian lycopsids are the precursors of the immense lycopsids that were the primary components of Carboniferous coal swamps (Cressler and Pfefferkorn, 2005). The increased stature of the plants in the Late Devonian was accompanied by a concomitant increase in root zone depth, which led to increased paleosol development (Driese and Mora, 1993). The development of paleosols has been linked to increased nutrient flow to the adjacent marine basins, a factor that may also explain increased anoxia, black shale formation, and marine extinctions (Algeo and Scheckler, 1998). The spread of plants on land from late Silurian through the Devonian set the stage for the radiation of animals in both freshwater and terrestrial settings. Large, suspension-feeding bivalves, Archanodon catskillensis, are recorded sporadically from throughout the Catskill Formation. Fossil terrestrial arthropods (first known from the Silurian) include millipedes (Wilson et al., 2005), scorpions, and a trigonotarbid arachnid (Shear, 2000) from the Catskill Formation. All of these are either detritivores or predators, and there is no evidence of herbivory on living plant tissue during the Late Devonian. It appears that the increased contribution of organic detritus by land plants to terrestrial and freshwater ecosystems during this time provided the primary productivity for these increasingly complex and diverse ecosystems. A diverse vertebrate assemblage, including placoderms, acanthodians, chondrichthyans, actinopterygians, and a range of sarcopterygians including at least three species of tetrapods (Daeschler et al., 1994, 2009; Daeschler, 2000b; Shubin et al., 2004) is known from the Catskill Formation. There are two distinct faunas that characterize the vertebrates from the Catskill Formation. The fauna dominated by the porolepiform sarcopterygian Holoptychius sp. and antiarch placoderm Bothriolepis sp. is characteristic of the Sherman Creek Member and much of the undifferentiated Catskill. This assemblage also includes rare occurrences of the rhizodont sarcopterygian Sauripterus taylori. These appear to be organisms mainly restricted to lower alluvial plain–deltaic habitats. Red Hill is characteristic of the other distinct fauna, which includes groenlandaspidid placoderms, a gyracanthid acanthodian, megalichthyid and tristochopterid sarcopterygians, and tetrapods, all from alluvial plain depositional facies. Some of the sarcopterygians (particularly the tetrapods) are lineages adapted for mobility in stream channels and shallow, obstructed waters, a habitat that the well-vegetated alluvial plains of the Catskill Delta Complex seem to have provided. Red Hill
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has been the subject of recent analyses of plant distribution in a Late Devonian landscape (Cressler, 2006) and the paleoecological conditions associated with terrestrialization during the Late Devonian (Cressler et al., 2010a). DAY 1 Road Log Cumulative miles (km) 0.0 (0.0)
3.5 (5.6)
30.8 (49.6)
39.4 (63.4) to 40.4 (65.0) 43.6 (70.2) 44.1 (71.0) 47.8 (76.9)
Directions and notes Take Exit 178 off Interstate 80 onto Route 220 North toward Lock Haven. The first few miles on Route 220 cross an anticlinal valley of Ordovician units. The ridges to north and south are composed of resistant sandstones of the Reedsville, Bald Eagle, and Juniata formations. Crossing through the Ordovician sandstones of Bald Eagle Mountain into Silurian units flanking the north side of the ridge (Tuscarora Formation). Route 220 continues to the northeast with Bald Eagle Mountain to the southeast (this is the last ridge of the Valley and Ridge Province) and the Allegheny Plateau to the northwest. Take Exit 29 for Route 15 North (also called Interstate 99). Route 15 North cuts into the Allegheny Plateau along Lycoming Creek. Between road log miles 34.5 and 40.5, a series of road cuts begin with Middle Devonian near-shore marine sediments of the Lock Haven Formation and after crossing the structural boundary of the Allegheny Front (Beautys Fault in this region) begins to move up-section. Excellent section exposed in road cuts through the lower part of the Catskill Formation (Irish Valley and Sherman Creek Members). Take exit for Route 14 North (Trout Run). Sharp U-turn onto access road (SR-17). Follow access road south, parallel to Route 15. Pull over onto right shoulder of road to examine blocks along roadbed.
Creek Member of the Catskill Formation exposed in the large vertical cut on the west side of Route 15. The Sherman Creek Member at this site is composed of laterally continuous siltstones and fine sandstones in 2–3-m-thick fining-upward cycles. The depositional setting for this section is a delta plain with lowgradient, shallow channels. Since 1994, vertebrate material has been collected from the debris slopes all along the raised portion of the highway roadbed. The fauna is dominated by the antiarch placoderm Bothriolepis sp. and the porolepiform sarcopterygian Holoptychius sp. A single pectoral fin and shoulder girdle of Sauripterus taylori was recovered from this site in 1995 (Fig. 3). The new specimen of Sauripterus taylori is quite informative and, remarkably, preserves the same portion of the skeleton, a right pectoral girdle and fin in ventral view, as the classic specimen described by Hall in 1843 (AMNH 3341) from ~40 km north of Powys Curve. The new specimen is described and discussed by Daeschler and Shubin (1998) and Davis et al. (2004). During construction of the roadway between Powys Curve and Trout Run, partially articulated skull material of a large tristichopterid, cf. Eusthenodon sp. was recovered. This material is
Stop 1. Powys Curve Coordinates: N41°20.840′ W77°05.614′ Construction along this stretch of Route 15 (Interstate 99) was completed in 1994. We will spend time looking at rocks and fossils along the debris slope between the highway road bed and the access road that runs adjacent to the highway along the bend in Lycoming Creek. At this stop, we can observe the Sherman
Figure 3. Ventral view of right pectoral fin of Sauripterus taylori discovered at Powys Curve, Lycoming County, Pennsylvania, in 1995. Note that the distal fin rays (lepidotrichia) are not preserved. Abbreviation: leps—lepidotrichia. Scale bar equals 5 cm.
Red Hill and other fossil sites in the Catskill Formation easily distinguished from Hyneria lindae, the large tristichopterid common at the Red Hill site in Clinton County (Stop 5). Both are derived members of the tristichopterid clade and typical of late Famennian large tristichopterids with cosmopolitan distribution. The cf. Eusthenodon sp. material from Powys Curve–Trout Run includes derived features such as no contact between the posterior supraorbital and intertemporal, a long parietal shield with the pineal foramen located in the posterior portion of the shield (well behind the orbits), and a lacrimal with a postorbital bar excluding the jugal from the orbital margin. The “Bothriolepis Problem” Thomson and Thomas (2001) and Weems (2004) reviewed the taxonomic status of Bothriolepis from the Catskill Formation. It is clear from these papers that the diagnosis of specieslevel features in Bothriolepis from the Catskill Formation is a microcosm of the issues concerning species-level taxonomy of this cosmopolitan Late Devonian genus more broadly. Bothriolepis material from the Catskill Formation was first described by Leidy (1856) as Stenacanthus nitidus based on a distal portion of a pectoral appendage from Blossburg, Tioga County, Pennsylvania. Newberry (1889) described a new bothriolepid species from the Catskill Formation, Bothriolepis leidyi, from Mansfield, Tioga County, Pennsylvania, acknowledging a synonymy with Stenacanthus nitidus. Newberry (1889) also described a new species, Bothriolepis minor from the Upper Devonian of Bradford County, Pennsylvania, that is distinguished by smaller size and finer ornament than Bothriolepis leidyi. Several authors have questioned or rejected the validity of Bothriolepis minor (e.g., Stensiö, 1948; Weems et al., 1981; Thomson and Thomas, 2001). Cope (1892) recognized the priority of Bothriolepis nitidus as a senior synonym of Bothriolepis leidyi, although Eastman (1907) changed the name to Bothriolepis nitida to correct the gender disagreement of the binomen. Weems et al. (1981) described Bothriolepis virginiensis from a Catskill Formation equivalent in Virginia. Thomson and Thomas (2001) suggested that Bothriolepis nitida be used to refer to all Bothriolepis material from the United States, mostly due to poor material and lack of diagnostic characters, although Weems (2004) maintained that B. virginiensis is a distinct species. The situation regarding the species-level taxonomy of Catskill Formation Bothriolepis suggests the need for further work, especially in light of the large sample of well-preserved Bothriolepis sp. material collected recently along the Route 15 corridor (Interstate 99) in Lycoming and Tioga counties (see Figure 6D for an example of recently collected material). Cumulative miles (km) 47.8 (76.9) 48.8 (78.5)
55.9 (90.0)
section into the Duncannon Member of the Catskill Formation. Pull over onto shoulder just before guardrail and sign for the Cogan House Exit.
Stop 2. Steam Valley Coordinates: N41°26.421″ W77°05.994′ Road work that was completed in 2010 created significant new exposures of the upper part of the Catskill Formation in the southbound lanes of Route 15 in Steam Valley, and in the area where Steam Valley Road / Green Valley Road intersects the northbound lanes of Route 15. Scattered vertebrate remains, particularly Bothriolepis sp. and Holoptychius sp., have been found in rock fall from the series of older exposures along the previously improved northbound lanes. An interesting horizon with freshwater bivalves (Archanodon catskillensis) can be observed in situ at this site. The dense packing of these infaunal suspension feeders speaks to the productivity of the Late Devonian continental ecosystem. Chamberlain et al. (2004) reviewed the paleoecological and biogeographic implications of archanodonts, suggesting that they inhabited freshwater floodplain and brackish estuarine environments of the Old Red Continent. Remington et al. (2008) studied the Archanodon-bearing sediments at this exposure and indicated that the Archanodon horizon occurs in the point bar facies within an incised channel body. Palynomorphs from near the base of the exposure suggest a Famennian 2c age (Traverse, 2003) for the strata at this site. Vertebrate collections from the recent construction work on the southbound lanes of Route 15 in Steam Valley include the typical Holoptychius sp. material, as well as a small phyllolepid placoderm trunk plate. Cumulative miles (km) 55.9 (90.0 58.3 (93.8)
63.3 (101.9) to 65.3 (105.1)
Directions and notes Carefully make U-turn to head north on access road. Stay left and follow short ramp onto Route 15 North. After passing Trout Run, Route 15 North climbs into Steam Valley and moves up
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71.3 (114.7)
Directions and notes Continue north on Route 15. Take exit for Route 184 (Steam Valley). Go left at top of ramp. Follow across overpass and to entrance for the Turkey Ranch Restaurant. Lunch stop. Return to overpass and get back on Route 15 North. A series of low road cuts on west side of the highway expose upper parts of the Catskill Formation. These cuts have produced a skull roof of the cosmopolitan rhynchodipterid lungfish Soederberghia groenlandica (discussed in Ahlberg et al., 2001), and an articulated body of the megalichthyid osteolepiform Sterropterygion brandei, which as described by Thomson (1972) and endochondral fin anatomy discussed by Rackoff (1980). Cresting Bloss Mountain, southern limb of the Blossburg Syncline.
6 75.0 (120.7)
77.0 (123.9) 78.0 (125.5) to 80.0 (128.7)
81.2 (130.7) 83.0 (133.6)
87.8 (141.3)
Daeschler and Cressler Exposures of Carboniferous units Burgoon Sandstone and Pottsville Group in center of syncline. Beginning to move down-section through the northern limb of the Blossburg Syncline. Huntley Mountain Formation grading downward into persistent red beds of the Catskill Formation. The DevonianCarboniferous boundary is within Huntley Mountain Formation. Exposure of grey silty sands of the Lock Haven Formation. Take exit for Covington/Canoe Camp. Go left at bottom of ramp, continue under overpass, and take immediate left onto ramp for Route 15 South. Pull over onto right shoulder just before guardrail. Please be very careful and aware of traffic, as the shoulder of the road is quite narrow.
and informative skull material of a tristichopterid sarcopterygian. The skull material of the tristichopterid is associated with scales (Fig. 6B) that are identical to Holoptychius radiatus Newberry 1889 and discussed below (Stop 4). Alongside the Tioga River, which runs northward on the valley floor, is an old railroad grade that was built to transport coal from Blossburg, an early source of high quality coal called “bloss.” This was the Blossburg-Corning Railroad and was traveled by James Hall in July of 1839 as he sought to clarify some New York geological boundary issues in Pennsylvania (Leviton and Aldrich, 1992). Just below the newly made highway exposures is a substantial man-made exposure of Catskill Formation along the railroad bed between Blossburg and Covington. The lithology at the railroad cut is very similar to the red-brown, medium sandstone matrix of the original Sauripterus taylori specimen (AMNH 3341) (Fig. 5). The fossiliferous nature of the rocks along the railroad bed is confirmed by specimens from Hall at the American Museum of Natural History identified as cf. Eusthenodon and with labels indicating that they were collected “at the railroad cut between Blossburg and Covington.” The Late Devonian fossils from this section induced Charles Lyell to take a
Stop 3. Blossburg-Covington Section Coordinates: N41°42.872′ W77°04.732′ This section of Route 15 bypassing the town of Covington was built in 2003 and 2004. The entire Catskill Formation is relatively thin at this location and is undifferentiated with regard to member designations. The contact between the Catskill and the overlying Huntley Mountain Formation is gradational (Berg and Edmunds, 1979). Sandstone bodies become increasing common upsection and take on a gray color in this transition zone from the meandering river facies of the Catskill Formation to predominantly braided river facies. The Devonian-Carboniferous boundary is within the lower part of the Huntley Mountain Formation. We will examine rocks and fossil material that are found in the large debris slope off the western shoulder of the highway. A diverse fauna has been collected from this section of the highway that includes separate mass mortality layers of adult and juvenile Bothriolepis sp. A small area of the debris slope is the source of numerous samples that preserve the mass mortality of juvenile Bothriolepis sp. material. Criswell et al. (2007) reported head plus trunk shield lengths of 20 mm to 30 mm for most individuals from the mass mortality layers (Fig. 4). The morphology of these individuals matches the expectations for juvenile morphology of Bothriolepis canadensis as established by trends in allometric growth discussed by Werdelin and Long (1986). Of particular note is the relatively large head shield, the relative size of the orbital fenestra, and a large ventral opening in the trunk shield. The occurrence of numerous, similar-sized, articulated individuals in a closely packed taphocoenosis may provide clues about the nature of the earliest life history of Bothriolepis. Other material recovered from this section includes adult Bothriolepis sp. (Fig. 6D), a phyllolepid placoderm, a single specimen of a palaeoniscid actinopterygian, Holoptychius sp.,
Figure 4. Bedding plane with multiple articulated juvenile individuals (in ventral view) of Bothriolepis sp. from the Catskill Formation near Blossburg, Tioga County, Pennsylvania. Scale bar equals 2 cm.
Red Hill and other fossil sites in the Catskill Formation trip to Blossburg (along this rail line) to investigate the similarity between the fossil fauna from Blossburg and that of the Old Red Sandstone in the British Isles (Leviton and Aldrich 1992). Cumulative miles (km) 87.8 (141.3) 90.9 (146.3)
108.5 (174.6) 110.3 (177.5)
112.8 (181.5)
Directions and notes Continue on Route 15 southbound. Take exit for Blossburg. Go left at bottom of ramp, continue under overpass, and take immediate left onto ramp for Route 15 North. Catskill Formation grading downward into Lock Haven Formation Take exit for Route 287 / Tioga. Go left at bottom of ramp, continue under overpass, and take immediate left onto ramp for Route 15 South. Enter and park at Tioga Welcome Center Rest Stop.
Stop 4. Tioga Welcome Center Rest Stop Coordinates: N41°54.026′ W77°07.542′ This highway facility has restrooms and vending machines and offers nice views to the west. To the north of the welcome
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center you can observe the gradational contact of the Catskill Formation (undifferentiated) with the underlying Lock Haven Formation. The contact zone between the gray sands and muds of the marine Lock Haven Formation and the red beds of the Catskill Formation is characterized by the presence of articulate brachiopods, Lingula and vertical burrows, and may represent a muddy tidal flat at the marine-terrestrial interface (Slane and Rygel, 2009). South of the welcome center the gradational contact between the Catskill Formation and the overlying Huntley Mountain Formation is mapped half way up the wooded hillside. The Catskill is thus relatively thin in this location (~100 m thick). The welcome center was built as part of a project to upgrade this section of the highway in 2001–2002. At that time, a section of the Catskill Formation was removed at the present site of the welcome center to create a flat building site. The excavations were examined numerous times during that phase of the work. Collected was fossil material of the placoderms Bothriolepis sp., Phyllolepis sp., a single element of a large dinichthyid, cf. Dunkleosteus sp., as well as the sarcopterygians Holoptychius sp., a tristichopterid, and the recently described lungfish Apatorhynchus opistheretmus (Friedman and Daeschler, 2006) (Fig. 6E). A palynomorph sample collected near road level across the highway from the welcome
Figure 5. Original illustration from Hall (1843) of Sauripterus taylori pectoral fin and scales found along a railroad cut near Blossburg, Tioga County, Pennsylvania.
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center suggests a Famennian 2b age for the lower part of this section (A. Traverse, 2004, personal commun.). Although fragmentary, the tristichopterid material from this site (also seen at Stop 3) is consistently associated with the same distinctive scale morphology (Fig. 6B). These distinct scales were named Holoptychius radiatus from specimens collected in the Blossburg area in the late nineteenth century (Newberry 1889). The type material of H. radiatus consists of distinctive scales with the characteristic tristichopterid feature of a raised, tear-drop shaped boss on the internal surface. With the suite of new specimens, this scale morphology can now be associated with lower jaw and skull material (e.g., Fig. 6C). A more complete description of this tristichopterid sarcopterygian (with a new generic attribution) is in order. Cumulative miles (km) 112.8 (181.5) 120.3 (193.6)
132.7 (213.6) 132.8 (213.7)
Directions and notes Continue southbound on Route 15. Take exit for Route 6, Mansfield/Wellsboro. Take a right at the bottom of the ramp following Route 6 West (towards Wellsboro). In Wellsboro, turn left at light (intersection of Route 6 and Route 660) onto Main Street. Turn right into parking lot for Penn Wells Hotel. End of Day 1.
DAY 2 Road Log Cumulative miles (km) 132.8 (213.7)
Directions and notes Turn right on Main Street and continue for one block. 132.9 (213.8) Left onto Route 287 South. 144.5 (232.5) Bear right to follow 287 South. 145.2 (233.8) Right on to Route 414 West. 175.3 (282.1) Right on to Route 44 North. 180.5 (290.5) Bear right to follow Route 44 North. 185.8 (299)Left on to Hyner Mountain Road (look for signs for Hyner Run State Park). 192.7 (310.1) Right on Route 120 West. 194.7 (313.3) Pull over on to wide shoulder at outcrop on right. Stop 5. Red Hill Coordinates: N41°20.645′ W77°40.800′ Introduction to Red Hill The Red Hill road cut is a kilometer-long exposure of slightly western-dipping alluvial sandstones, siltstones and paleosols of the Duncannon Member of the Catskill Formation. The western part of the exposure is dominated by channel sandstones. The face of the road cut is quite steep here and reaches a height of 30 m,
thus fossil prospecting has been restricted to examination of the frequent rock falls. A few fossil discoveries have been made in the finer-grained rocks that have fallen, but collecting has been minimal in this part of the outcrop due to taphonomic and logistical factors. The lack of collecting, however, is compensated for by the considerable sequence of fluvial strata that can be observed here, indicative of a dynamic Late Devonian alluvial plain. The eastern portion of the road cut is dominated by finergrained channel margin and inter-channel siltstones and paleosols. A vertically thin (3 m) but laterally broad (~200 m exposed) sequence of fossiliferous strata in this portion of the outcrop is the source of the abundant fossil remains from Red Hill. The fossiliferous lenses reflect several different styles of deposition from low energy standing water to higher energy lags. The slope of the outcrop is not cut as steeply in these fine-grained layers. The presence of talus and the creation of terraces during fossil prospecting allow more access to the strata for close observation and continued collecting. The talus slopes are good for collecting fragmentary specimens of fish teeth and scales, and plant compressions. Please USE CAUTION when climbing the rock face, and always be aware of traffic at this roadside location. Red Hill has produced one of the most diverse and abundant samples of life from a Late Devonian continental ecosystem. At least thirteen species of plants have been identified, representing an ecological patchwork of progymnosperm forests, lycopsid wetlands, zygopterid fern glades, and patches of early spermatophytes that occupied sites disturbed by fires. Two newly discovered terrestrial arthropods have been described from Red Hill, a trigonotarbid arachnid and a myriapod. The remains of at least fifteen species of vertebrate have been recovered, including placoderms, an acanthodian, chondrichthyans, palaeoniscid actinopterygians, finned sarcopterygians, and three early tetrapod species. A variety of inter-channel depositional settings formed a wide range of aquatic and terrestrial habitats as a result of the periodic avulsion of meandering rivers across the alluvial plain. These habitats formed a crucible of evolution for plants and animals, including innovations critical to the further development of life on land. Red Hill Sedimentology Traditionally, sedimentation in upper alluvial and coastal plain settings has been envisioned as being produced by singlethread meandering rivers. However, the pattern of sedimentological structures at Red Hill conforms to a model of periodic avulsion like that described in recent studies of modern fine-grained fluvial systems that show these systems cycling through two stages with a typical period on the order of 1000 years (Smith et al., 1989; Soong and Zhao, 1994; Slingerland and Smith, 2004). Stage I begins when a channel changes course by permanently breaching its levee. A sediment wedge progrades down-current from the avulsion site resulting in intense alluviation of the floodplain as the system changes from a single channelized flow into rapidly evolving distributary channels. These channels split and coalesce in a complex network while scouring the floodplain to create
Red Hill and other fossil sites in the Catskill Formation
Figure 6. Typical vertebrate fauna from the Catskill Formation along Route 15 (Interstate 99) in Lycoming and Tioga counties, Pennsylvania. (A) Scales of porolepiform, Holoptychius sp. (B) Scales of tristichopterid, Holoptychius radiatus. (C) Rostral portion of lower jaws of H. radiatus with submandibulars and gulars. (D) Dorsal view of adult antiarch placoderm Bothriolepis sp. from mass mortality zone. (E) Partial skull in dorsal view of lungfish, Apatorhynchus opistheretmus. (F) Pectoral fin of rhizodontid, Sauripterus taylori. Scale bars equal 2 cm.
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transient ponds and lakes as they encounter preexisting channel levees and floodplain vegetation. Commonly observed deposits of this stage are: (1) coarser-grained crevasse splays of a variety of lobate, elliptical, or elongate shapes (Smith, 1986; O’Brien and Wells, 1986; Bristow, 1999); and (2) finer-grained lake and distal splay deposits in which rapid burial has preserved organic debris from oxidation. The former are observed at Red Hill in the variety of sandstone bodies ranging in morphology from wedgeshaped lenticular, to flat-bottomed and convex-upward. The latter comprise the main fossiliferous strata at Red Hill, further described below as comprising four taphofacies. Stage II of the avulsion cycle begins when distributary channels once again follow the regional slope and start flowing subparallel to the parent channel where they are eventually abandoned as flow is captured into a new trunk channel similar in scale to the parent channel that initially avulsed (Smith et al., 1989). Sedimentation rates are low, allowing soil formation to resume on the floodplain. The new trunk channel incises into its earlier avulsion deposits, creating a new meander belt that is relatively narrow and only reworks a small fraction of the Stage I avulsion fill floodplain deposits into meander belt deposits. Evidence at Red Hill for Stage II of the avulsion cycle consists of the extensive paleosols easily observed at the eastern end of the outcrop and the massive channel sandstone bodies observable at the western end of the outcrop. The considerable lateral and vertical variation within the strata at Red Hill reflects the heterogeneity of depositional facies of the avulsion model. This variation in depositional facies, in turn, results in the uncommon circumstance of a range of taphonomic modes preserving both plant and animal remains at the same site. Four different taphofacies preserve fossil material: sorted microfossil horizons, basal lags, channel-margin and standing-water deposits. Well-sorted microfossil accumulations and basal lag deposits contain abundant, but fragmentary, vertebrate material that may be allochthonous and thus have poor time and ecological fidelity. The channel-margin taphofacies contains isolated and associated vertebrate material, often in discrete lenses. The character of the entombing sediments indicates that the fossils accumulated along the strandline of the aggrading margins of temporary channels in overbank areas after avulsion episodes. Deposits of this sort have the potential to accumulate relatively quickly, and the fact that the taphofacies shows little or no abrasion or pre-depositional weathering of accumulated material indicates that the associated taxa were living penecontemporaneously in the areas near the site of deposition. The standing-water taphofacies is represented by green-gray siltstones with abundant plant material and an occasional occurrence of arthropod and vertebrate remains. The vertebrate remains from this setting are black and “carbonized” suggesting different water chemistry (perhaps more acidic) and diagenetic conditions than other taphofacies at Red Hill. These deposits represent low energy, reducing environments, such as floodplain ponds and distal splay settings that can provide excellent temporal and ecological fidelity.
Red Hill Flora (Table 1) All the of the well-preserved plant fossils from Red Hill have come from a single gray-green siltstone pond deposit at the eastern end of the outcrop, with the exception of a few significant specimens found in a rock that had fallen from the western end. The floral characteristics of Red Hill are typical of a Late Devonian plant assemblage, specifically a subtropical Archaeopteris forest. Four Archaeopteris leaf morphospecies are dominated by A. macilenta and A. hibernica (Fig. 7C). This progymnosperm tree is an index fossil for the Late Devonian (Banks, 1980), as is the second most abundant set of plant remains at Red Hill, the zygopterid fern assigned to Rhacophyton ceratangium. The early diversification of arborescent lycopsids are represented by numerous decorticated stems (Fig. 7B), some identifiable as Lepidodendropsis. Also, well-preserved remains of cormose isoetalean bases and stems have been described as Otzinachsonia beerboweri (Cressler and Pfefferkorn, 2005). Two species of spermatophytes are present, including the newly described species Duodimidia pfefferkornii (Fig. 7A; Cressler et al., 2010b) characterized by fused symmetric cupule pairs, and Aglosperma quadrapartita (Cressler, 2006). The palynological age of the strata make it coeval with other sites preserving the earliest recorded spermatophytes in Belgium and West Virginia (FaironDemaret and Scheckler, 1987; Rothwell et al., 1989). Other minor floral elements include the stauripterid fern Gillespiea and a variety of barinophytes (Cressler, 2006). Major plant groups found at other Late Devonian sites, but not yet discovered at Red Hill, are the sphenopsids and cladoxylaleans. Red Hill Fauna (Table 1) The arthropod fauna discovered at Red Hill is likely only a very limited subset of the invertebrate community present in the floodplain ecosystem. A trigonotarbid arachnid (Fig. 7M; Shear, 2000) and archidesmid myriapod (Fig. 7L; Wilson et al., 2005) have been described from the standing-water taphofacies, but greater diversity is evidenced by enigmatic body impressions, burrow traces and walking traces. The vertebrate assemblage represents a diverse community that was living in aquatic habitats within the alluvial plain of the Catskill Delta Complex. These include bottom feeders, durophages, filter feeders and a wide range of predators. The placoderm assemblage is dominated by the small groenlandaspidid, Turrisaspis elektor (Fig. 7D), one of the most common taxa from the site (Daeschler et al., 2003). Lane and Cuffey (2005) recognize a new species of Phyllolepis, a cosmopolitan placoderm reaching the Euramerica landmass in the Famennian. Fin spines and pectoral girdle elements of the acanthodian Gyracanthus (cf. G. sherwoodi) (Fig. 7G) are common, as are small isolated teeth of the chondichthyan Ageleodus (Fig. 7F; Downs and Daeschler, 2001). Rare xenacanthiform chondrichthyan teeth have been recognized (Fig. 7E). Among the bony fish, the small palaeoniscid actinopterygian, Limnomis delaneyi (Fig. 7H; Daeschler 2000a), and the large tristichopterid sarcopterygian, Hyneria lindae (Fig. 7K; Thomson, 1968), are the dominant components. Other sarcopterygians
Red Hill and other fossil sites in the Catskill Formation
TABLE 1. RED HILL FAUNA AND FLORA RED HILL FAUNA
RED HILL FLORA
Chelicerata Arachnida Trigonotarbida Palaeocharinidae Gigantocharinus szatmaryi Shear Myriapoda Diplopoda Archidesmida Zanclodesmidae Orsadesmus rubecollus Wilson Vertebrata Placodermi Phyllolepida Phyllolepididae Phyllolepis rossimontina Lane and Cuffey Arthrodira Groenlandaspididae Groenlandaspis pennsylvanica Daeschler Turrisaspis elektor Daeschler Acanthodii Climatiiformes Gyracanthidae Gyracanthus cf. G. sherwoodi Newberry Chondrichthyes Ctenacanthiformes Ctenacanthidae Ctenacanthus sp. Xenacanthiformes Indet. Insertae Sedis Ageleodus pectinatus (Agassiz) Osteichthyes Actinopterygii Palaeonisciformes Limnomis delaneyi Daeschler Indet. Sarcopterygii Dipnoi Indet. Crossopterygii Rhizodontidae cf. Sauripterus sp. Indet. Megalichthyidae Indet. Tristichopteridae Hyneria lindae Thomson Amphibia Ichthyostegalia Hynerpeton bassetti Daeschler Densignathus rowei Daeschler cf. Whatcheeridae Indet.
Zosterophyllopsida Barinophytales cf. Protobarinophyton sp. Barinophyton obscurum (Dun) White Barinophyton sibericum Petrosian Lycopsida Isoetales Otzinachsonia beerboweri Cressler and Pfefferkorn cf. Lepidodendropsis Lutz Filicopsida Zygopteridales Rhacophyton ceratangium Andrews and Phillips Stauropteridales Gillespiea randolphensis Erwin and Rothwell Progymnospermopsida Archaeopteridales Archaeopteris macilenta (Lesq.) Carluccio et al. Archaeopteris hibernica (Forbes) Dawson Archaeopteris obtusa Lesquereaux Archaeopteris halliana (Göppert) Dawson Gymnospermopsida Pteridospermales cf. Aglosperma quadrapartita Hilton and Edwards Duodimidia pfefferkornii Cressler et al.
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Figure 7. Typical fauna and flora from the Catskill Formation at Red Hill, Clinton County, Pennsylvania. (A) Early spermatophyte, Duodimidia pfefferkornii. (B) Lycopod stem, cf. Lepidodendropsis. (C) Progymnosperm, Archaeopteris sp. (D) Head and truck shields in oblique lateral view of groenlandaspidid placoderm, Turrisaspis elektor. (E) Tooth of xenacanthiform chondrichthyan. (F) Tooth of chondrichthyan, Ageleodus pectinatus. (G) Pectoral fin spine of gyracanthid acanthodian, Gyracanthus cf. G. sherwoodi. (H) Body of small actinopterygian, Limnomis delaneyi. (I) Small lungfish tooth plate. (J) Skull roof of megalichthyid osteolepidid, gen. et sp. indet. (K) Isolated vomerine teeth of large tristichopterid, Hyneria lindae. (L) Millipede, Orsadesmus rubecollus. (M) Palaeocharinid arachnid, Gigantocharinus szatmaryi. Scale bars equal 2 cm (B, C, D, G, J, K), 5 mm (A, H, I, L, M), and 1 mm (E, F).
Red Hill and other fossil sites in the Catskill Formation include rhizodontid and megalichthyid (Fig. 7J) forms. Early tetrapod remains are rare and are represented by isolated skeletal elements, although recent analysis suggests that at least three penecontemporaneous taxa are present: Hynerpeton bassetti (Fig. 8A), Densignathus rowei (Fig. 8B), and a whatcheerid-like form (Fig. 8F, 8I) (Daeschler et al., 2009). Interestingly, taxa such as Bothriolepis and Holoptychius that are common at most other late Famennian sites in the Catskill Formation are absent at Red Hill, except for Holoptychius sp. scales from a rock fall from high in the Red Hill section. Red Hill Paleoecology A paleoecological analysis of the Red Hill plant community (Cressler, 2006) characterized the vegetation as a subtropical Archaeopteris floodplain forest interspersed with lycopsid wetlands and widespread stands of Rhacophyton on the floodplain
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and along water margins (Figs. 9 and 10). Taphonomic and fossildistribution evidence was derived from systematic sampling of the floodplain pond deposit. The plant fossils had undergone little or no transport. The evidence provided in that study was interpreted to support a model of habitat partitioning of the landscape by the plants at a high phylogenetic level, a characteristic of midPaleozoic plant communities (DiMichele and Bateman, 1996). The pattern of plant distribution at Red Hill is similar to that seen in other Late Devonian paleoecological studies (Scheckler, 1986a, 1986b; Rothwell and Scheckler, 1988; Scheckler et al., 1999). Lycopsids dominated the wettest portions of the floodplain, whereas Rhacophyton dominated the poorly drained floodplain margins. Archaeopteris grew in the better-drained areas of the landscape and seed plants grew opportunistically. At Red Hill the seed plants apparently flourished following fires that cleared the Rhacophyton groundcover (Cressler, 2001). This is indicated
Figure 8. Isolated remains of early tetrapods from Red Hill, Clinton County, Pennsylvania. (A) Left shoulder girdle of Hynerpeton bassetti. (B) Left lower jaw of Densignathus rowei. (C) Partial right lower jaw. (D) Ventral and dorsal views of humerus (ANSP 21350). (E) Ventral view of femur. (F) Postorbital. (G) Jugal. (H) Jugal. (I) Lacrimal. Abbreviations: adb—adductor blade; adc—adductor crest; ang—angular; art—articular; cl—cleithrum; dent—dentary; ect—ectepicondyle; ent—entepicondyle; gf—glenoid fossa; it—internal trochanter; orb—orbit; raf—radial facet; sc—sensory canal; sgb—supraglenoid buttress; sur—surangular; tf—tibial facet; ulf—ulnar facet. Scale bars equal 1 cm except in F and I, where scale bars equal 0.5 cm.
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by a succession of Rhacophyton-to-charcoal-to-spermatophyte remains within the small-scale stratigraphic profile (Cressler, 2001; 2006). Fires presumably were associated with the wet and dry seasonal cycle that prevailed in the Late Devonian Catskill Delta system, as also indicated by the calcretes and vertic structures in the paleosols. The floodplain habitats at Red Hill provided a range of conditions for the cohabitation of plants and animals (Cressler et al., 2010a). Plant communities were partitioned on the floodplain across a range of environments from elevated and betterdrained levees to low, wetland habitats (Cressler, 2006). The aquatic settings include open river channels, shallow channel margins, anastomosing temporary channels, and floodplain ponds in interfluves that were subject to periodic flooding. This heterogeneity is expressed even on the local scale at the Red Hill site, as might be expected with the avulsion model of floodplain aggradation. Seasonal flooding and drying probably had a significant role in the annual cycles of plants and animals and their evolution.
Figure 9. The progymnosperm Archaeopteris and understory fern Rhacophyton growing on the edge of a Devonian floodplain pond. Illustration courtesy of Stephen Greb.
Cumulative miles (km) 194.7 (313.3) 195.7 (314.9) 196.0 (315.4)
Directions and notes Continue on Route 120 West. After crossing over bridge at Young Woman’s Creek, turn right onto School House Road. Turn left into rear parking area of the Chapman Township Municipal Building (white building with maintenance yard in rear). Park in the rear parking area.
Stop 6. Red Hill Field Station The people of Chapman Township have allowed us to renovate the second floor of their municipal building to use as our “Red Hill Field Station and Museum.” Mr. Doug Rowe is the driving force behind this facility. The Field Station serves as an important educational tool for visitors to the Red Hill site, including local school groups, fossil clubs, and casual visitors. It also provides a place for our research group to get out of the hot, cold,
Figure 10. Rhacophyton-dominated Devonian swamps, but arborescent lycopsids became increasingly common in the Carboniferous. Illustration courtesy of Stephen Greb.
Red Hill and other fossil sites in the Catskill Formation or wet weather while working at Red Hill. Please take some time to explore in the Field Station. Examples of most of the taxa from the Red Hill site are on display. Most are original fossil material. Almost 1,000 specimens from Red Hill are catalogued in the collections at the Academy of Natural Sciences in Philadelphia. Some of those specimens are presented as casts and photographs at the Field Station. Cumulative miles (km) 196.0 (315.4) 196.3 (315.9) 197.3 (317.5) 219.7 (353.8) 220.8 (355.3) 221.4 (356.3) 228.7 (368.1)
Directions and notes Turn right out of Municipal Building parking area. Turn left onto Route 120 East. Passing Red Hill exposure. Turn left at light to stay on Route 120 East in to Lock Haven. Turn right to stay on Route 120 East. Stay in right lane, and follow signs for Milesburg/Route 220 South Take exit for Route 80. End of Road Log.
ACKNOWLEDGMENTS There have been a large number of participants in our ongoing work in the Catskill Formation. We thank all for their dedicated work toward building a better understanding of the paleobiological and geological nature of the Catskill Formation in Pennsylvania. We would like to especially mention Douglas Rowe, Janice Pycha, Rudy Slingerland, Daniel Peterson, Stephen Greb, Frederick Mullison, Jason Downs, John Sime, and the Pennsylvania Department of Transportation for their invaluable contributions to this research and assistance in creating this field guide. REFERENCES CITED Ahlberg, P.E., Johanson, Z., and Daeschler, E.B., 2001, The Late Devonian lungfish Soederberghia (Sarcopterygii, Dipnoi) from Australia and North America, and its biogeographic implications: Journal of Vertebrate Paleontology, v. 21, no. 1, p. 1–12, doi:10.1671/0272-4634(2001)021[0001: TLDLSS]2.0.CO;2. Algeo, T.J., and Scheckler, S.E., 1998, Terrestrial-marine teleconnections in the Devonian: Links between the evolution of land plants, weathering processes, and marine anoxic events: Philosophical Transactions of the Royal Society of London, B, Biological Sciences, v. 353, p. 113–130, doi:10.1098/rstb.1998.0195. Arnold, C.A., 1936, Observations on fossil plants from the Devonian of eastern North America. II. Archaeopteris macilenta and A. sphenophyllifolia of Lesquereux: Contributions from the Museum of Paleontology, University of Michigan, v. 5, no. 3, p. 49–56. Arnold, C.A., 1939, Observations on fossil plants from the Devonian of eastern North America. IV. Plant remains from the Catskill Delta deposits of northern Pennsylvania and southern New York: Contributions from the Museum of Paleontology, University of Michigan, v. 5, no. 11, p. 271–314. Banks, H.P., 1980, Floral assemblages in the Siluro-Devonian, in Dilcher, D.L., and Taylor, T.N., eds., Biostratigraphy of Fossil Plants: Pennsylvania, Dowden, Hutchinson, and Ross, p. 1–24. Berg, T.M., and Edmunds, W.E., 1979, The Huntley Mountain Formation: Catskill-to-Burgoon Transition in North-Central Pennsylvania: Pennsylvania Geological Survey, Information Circular 83, p. 1–80.
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Bristow, C.S., 1999, Crevasse splays from the rapidly aggrading sand-bed braided Niobrara River, Nebraska: effect of base-level rise: Sedimentology, v. 46, p. 1029–1047, doi:10.1046/j.1365-3091.1999.00263.x. Chamberlain, J.A., Jr., Friedman, G.M., and Chamberlain, R.B., 2004, Devonian Archanodont Unionoids from the Catskill Mountains of New York: Implications for the paleoecology and biogeography of the first freshwater bivalves: Northeastern Geology and Environmental Sciences, v. 26, no. 3, p. 211–229. Cope, E.D., 1892, On some new and little known Paleozoic vertebrates: Proceedings of the American Philosophical Society, v. 30, p. 221–229. Cressler, W.L., III, 2001, Evidence of earliest known wildfires: Palaios, v. 16, p. 171–174. Cressler, W.L., III, 2006, Plant paleoecology of the Late Devonian Red Hill locality, north-central Pennsylvania, an Archaeopteris-dominated wetland plant community and early tetrapod site, in DiMichele, W.A., and Greb, S., eds., Wetlands through Time: Geological Society of America Special Paper 399, p. 79–102, doi:10.1130/2006.2399(04). Cressler, W.L., III, and Pfefferkorn, H.W., 2005, A late Devonian isoetalean lycopsid, Otzinachsonia beerboweri, gen. et sp. nov., from north-central Pennsylvania, USA: American Journal of Botany, v. 92, p. 1131–1140, doi:10.3732/ajb.92.7.1131. Cressler, W.L., III, Daeschler, E.B., Slingerland, R., and Peterson, D.A., 2010a, Terrestrialization in the Late Devonian: a palaeoecological overview of the Red Hill site, Pennsylvania, USA, in Vecoli, M., Clement, G., and Meyer-Berthaud, B., eds., The Terrestrialization process: Modelling Complex Interactions at the Biosphere-Geosphere Interface: Geological Society of London Special Publication 399, p. 111–128. Cressler, W.L., III, Prestianni, C., and LePage, B.A., 2010b, Late Devonian spermatophyte diversity and the paleoecology at Red Hill, north-central Pennsylvania, USA: International Journal of Coal Geology, v. 83, p. 91–102, doi:10.1016/j.coal.2009.10.002. Criswell, K., Downs, J. and Daeschler, E., 2007, Mass mortality of juvenile placoderms (Bothriolepis sp.) from the Catskill Formation (Upper Devonian), Tioga County, Pennsylvania [abs.]: Journal of Vertebrate Paleontology, v. 27 (supplement to 3), p. 62A. Daeschler, E.B., 2000a, An early actinopterygian fish from the Catskill Formation (Late Devonian, Famennian) in Pennsylvania, U.S.A: Proceedings. Academy of Natural Sciences of Philadelphia, v. 150, p. 181–192. Daeschler, E.B., 2000b, Early tetrapod jaws from the Late Devonian of Pennsylvania, USA: Journal of Paleontology, v. 74, p. 301–308, doi:10.1666/0022 -3360(2000)0742.0.CO;2. Daeschler, E.B., and Shubin, N.H., 1998, Fish with Fingers?: Nature, v. 391, p. 133, doi:10.1038/34317. Daeschler, E.B., Shubin, N.H., Thomson, K.S., and Amaral, W.W., 1994, A Devonian tetrapod from North America: Science, v. 265, p. 639–642, doi:10.1126/science.265.5172.639. Daeschler, E.B., Frumes, A., and Mullison, C.F., 2003, Groenlandaspidid placoderm fishes from Late Devonian of North America: Records of the Australian Museum, v. 55, no. 1, p. 45–60, doi:10.3853/j.0067 -1975.55.2003.1374. Daeschler, E.B., Clack, J.A., and Shubin, N.H., 2009, Late Devonian tetrapod remains from Red Hill, Pennsylvania, USA: How much diversity?: Acta Zoologica, v. 90, no. 1, p. 306–317, doi:10.1111/j.1463 -6395.2008.00361.x. Davis, M.C., Shubin, N.H., and Daeschler, E.B., 2004, A new specimen of Sauripterus taylori (Sarcopterygii, Osteichthyes) from the Famennian Catskill Formation of North America: Journal of Vertebrate Paleontology, v. 24, p. 26–40, doi:10.1671/1920-3. DiMichele, W.A., and Bateman, R.M., 1996, Plant paleoecology and evolutionary inference: two examples from the Paleozoic: Review of Palaeobotany and Palynology, v. 90, p. 223–247, doi:10.1016/0034-6667(95)00085-2. Downs, J.P., and Daeschler, E.B., 2001, Variation within a large sample of Ageleodus pectinatus teeth (Chondichthyes) from the Late Devonian of Pennsylvania, U.S.A: Journal of Vertebrate Paleontology, v. 21, no. 4, p. 811– 814, doi:10.1671/0272-4634(2001)021[0811:VWALSO]2.0.CO;2. Driese, S.G., and Mora, C.I., 1993, Physico-chemical environment of pedogenic carbonate formation in Devonian vertic paleosols, central Appalachians, U.S.A: Sedimentology, v. 40, p. 199–216, doi:10.1111/j.1365-3091.1993.tb01761.x. Eastman, C.R., 1907, Devonic fishes of the New York formations: New York State Museum Memoir, v. 10, 193 p. Faill, R.T., 1985, The Acadian Orogeny and the Catskill Delta, in Woodrow, D.L., and Sevon, W.D., eds., The Catskill Delta: Geological Society of America Special Paper 201, p. 39–50.
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Fairon-Demaret, M., and Scheckler, S.E., 1987, Typification and redescription of Moresnetia zalesskyi Stockmans, 1948, an early seed plant from the Upper Famennian of Belgium: Bulletin de L’Institut Royal les Sciences Naturalles de Belgique: Sciences del la Terre, v. 57, p. 183–199. Friedman, M., and Daeschler, E.B., 2006, Late Devonian (Famennian) lungfishes from the Catskill Formation of Pennsylvania, USA: Palaeontology, v. 49, no. 6, p. 1167–1183, doi:10.1111/j.1475-4983.2006.00594.x. Hall, J., 1843, Fourth annual report of the survey of the Fourth Geological District: Albany, New York, New York State Assembly Document 50, p. 393–394, 453. Harvey, A., 1998, A paleoenvironmental reconstruction in the Devonian Sherman Creek Member of the Catskill Formation in central Pennsylvania [M.S. thesis]: Philadelphia, Pennsylvania, Temple University, 90 p. Lane, J.A., and Cuffey, R.J., 2005, Phyllolepis rossimontina sp. nov. (Placodermi) from the uppermost Devonian at Red Hill, north-central Pennsylvania: Revista Brasileira de Paleontologia, v. 8, no. 2, p. 117–126, doi:10.4072/rbp.2005.2.04. Leidy, J., 1856, Description of two ichthyodorulites: Proceedings. Academy of Natural Sciences of Philadelphia, v. 8, p. 11–12. Lesquereux, L., 1884, Description of the Coal Flora of the Carboniferous Formation in Pennsylvania and throughout the United States. Second Geological Survey of Pennsylvania. Volume III. Report of Progress: State Printer of Pennsylvania, Harrisburg, p. 695–977. Leviton, A.E., and Aldrich, M.L., 1992, Fishes of the Old Red Sandstone and systemic boundaries, Blossburg, Pennsylvania 1830–1900: Earth Sciences History, v. 11, p. 21–29. Meyer-Berthaud, B., Scheckler, S.E., and Wendt, J., 1999, Archaeopteris is the earliest known modern tree: Nature, v. 398, p. 700–701, doi:10.1038/19516. Newberry, J.S., 1889, The Paleozoic fishes of North America: U.S. Geological Survey Monograph, v. 16, 340 p., 53 pls. O’Brien, P.E., and Wells, A.T., 1986, A small alluvial crevasse splay: Journal of Sedimentary Petrology, v. 56, p. 876–879. Pettitt, J.M., and Beck, C.B., 1968, Archaeosperma arnoldii—a cupulate seed from the Upper Devonian of North America: Contributions from the Museum of Paleontology, University of Michigan, v. 22, p. 139–154. Rackoff, J.S., 1980, The origin of the tetrapod limb and the ancestry of tetrapods, in Panchen, A.L., ed., The Terrestrial Environment and the Origin of Land Vertebrates: Academic Press, London. p. 255–292. Remington, K., Daeschler, E.B., and Rygel, M.C., 2008, Sedimentology of an Archanodon-bearing channel body in the Catskill Formation (Upper Devonian) near Steam Valley, Pennsylvania [abs.]: Geological Society of America Abstracts with Programs, v. 40, no. 2, p. 82. Rothwell, G.W., and Scheckler, S.E., 1988, Biology of ancestral gymnosperms, in Beck, C.B., ed., Origins and evolution of gymnosperms: New York, Columbia University Press, p. 85–134. Rothwell, G.W., Scheckler, S.E., and Gillespie, W.H., 1989, Elkinsia gen nov., a Late Devonian gymnosperm with cupulate ovules: Chicago, Illinois, Botanical Gazette, v. 150, p. 170–189, doi:10.1086/337763. Scheckler, S.E., 1986a, Floras of the Devonian-Mississippian transition, in Gastaldo, R.A., and Broadhead, T.W., eds., Land plants: notes for a short course: Knoxville, Tennessee, University of Tennessee, Studies in Geology, v. 15, p. 81–96. Scheckler, S.E., 1986b, Geology, floristics and paleoecology of Late Devonian coal swamps from Appalachian Laurentia (U.S.A.): Annales de la Société Géologique de Belgique, v. 109, p. 209–222. Scheckler, S.E., Cressler, W.L., Connery, T., Klavins, S., and Postnikoff, D., 1999, Devonian shrub and tree dominated landscapes (abstract): XVI International Botanical Congress, v. 16, p. 13. Sevon, W.D., 1985, Nonmarine facies of the Middle and Late Devonian Catskill coastal alluvial plain, in Woodrow, D.L., and Sevon, W.D., eds., The Catskill Delta: Geological Society of America Special Paper 201, p. 79–90.
Shear, W.A., 2000, Gigantocharinus szatmaryi, a new trigonotarbid arachnid from the Late Devonian of North America (Chelicerata, Arachnida, Trigonotarbida): Journal of Paleontology, v. 74, p. 25–31, doi:10.1666/0022 -3360(2000)0742.0.CO;2. Shubin, N.H., Daeschler, E.B., and Coates, M.I., 2004, The early evolution of the tetrapod humerus: Science, v. 304, no. 5667, p. 90–93, doi:10.1126/ science.1094295. Slane, D.C., and Rygel, M.C., 2009, Marginal-marine facies of the Catskill Formation (Upper Devonian), Tioga County, Pennsylvania [abs.]: Geological Society of America Abstracts with Programs, v. 41, no. 7, p. 145. Slingerland, R., and Smith, N.D., 2004, River avulsions and their deposits: Annual Review of Earth and Planetary Sciences, v. 32, p. 257–285, doi:10.1146/annurev.earth.32.101802.120201. Smith, D.G., 1986, Anastomosing river deposits, sedimentation rates and basin subsidence, Magdalena River, northwestern Colombia, South America: Sedimentary Geology, v. 46, p. 177–196, doi:10.1016/0037 -0738(86)90058-8. Smith, N.D., Cross, T.A., Dufficy, J.P., and Clough, S.R., 1989, Anatomy of an avulsion: Sedimentology, v. 36, p. 1–23, doi:10.1111/j.1365-3091.1989. tb00817.x. Soong, T.W.M., and Zhao, Y., 1994, The flood and sediment characteristics of the Lower Yellow River in China: Water International, v. 19, p. 129–137, doi:10.1080/02508069408686216. Stensiö, E.A., 1948, On the Placodermi of the Upper Devonian of East Greenland. II. Antiarchi: subfamily Bothriolepinae: Meddelelser om Grønland, v. 139, p. 1–622. Streel, M., Higgs, K., Loboziak, S., Riegel, W., and Steemans, P., 1987, Spore stratigraphy and correlation with faunas and floras in the type marine Devonian of the Ardenne-Rhenish regions: Journal of Palaeobotany and Palynology, v. 50, p. 211–229, doi:10.1016/0034-6667(87)90001-7. Thomson, K.S., 1968, A new Devonian fish (Crossopterygii: Rhipidistia) considered in relation to the origin of the Amphibia: Postilla, v. 124, p. 1–13. Thomson, K.S., 1972, New evidence on the evolution of paired fins in Rhipidistia and the origin of the tetrapod limb, with description of a new genus of Osteolepidae: Postilla, v. 157, p. 1–7. Thomson, K.S., and Thomas, B., 2001, On the status of species of Bothriolepis (Placodermi, Antiarchi) in North America: Journal of Vertebrate Paleontology, v. 21, no. 4, p. 679–686, doi:10.1671/0272-4634(2001) 021[0679:OTSOSO]2.0.CO;2. Traverse, A., 2003, Dating the earliest tetrapods: a Catskill palynological problem in Pennsylvania: Courier Forschungs-Institut Senckenberg, v. 241, p. 19–29. Weems, R.E., 2004, Bothriolepis virginiensis, a valid species of placoderm fish separable from Bothriolepis nitida: Journal of Vertebrate Paleontology, v. 24, no. 1, p. 245–250, doi:10.1671/20. Weems, R.E., Beem, K.A., and Miller, T.A., 1981, A new species of Bothriolepis (Placodermi: Bothriolepidae) from the Upper Devonian of Virginia (USA): Proceedings of the Biological Society of Washington, v. 94, p. 984–1004. Werdelin, L., and Long, J.A., 1986, Allometry in the placoderm Bothriolepis canadensis and its significance to antiarch evolution: Lethaia, v. 19, p. 161–169, doi:10.1111/j.1502-3931.1986.tb00727.x. Wilson, H.M., Daeschler, E.B., and Desbiens, S., 2005, New flat-backed archipolypodan millipedes from the Upper Devonian of North America: Journal of Paleontology, v. 79, p. 738–744, doi:10.1666/0022-3360 (2005)079[0738:NFAMFT]2.0.CO;2.
MANUSCRIPT ACCEPTED BY THE SOCIETY 20 DECEMBER 2010
Printed in the USA
The Geological Society of America Field Guide 20 2011
An introduction to structures and stratigraphy in the proximal portion of the Middle Devonian Marcellus and Burket/Geneseo black shales in the Central Appalachian Valley and Ridge Terry Engelder Rudy Slingerland Michael Arthur Department of Geosciences, The Pennsylvania State University, University Park, Pennsylvania 16802, USA Gary Lash Department of Geosciences, SUNY Fredonia, Fredonia, New York 14063, USA Daniel Kohl D.P. Gold Department of Geosciences, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
ABSTRACT A Marcellus-Burket/Geneseo field trip in the Appalachian Valley and Ridge features both brittle and ductile structures. The degree to which these structures have developed depends on both lithology, which is a function of the stratigraphic architecture of the Devonian Appalachian Basin and position relative to the foreland during the Alleghanian Orogeny. Joints are best developed in the black shales and the units immediately above with the J2 joint set most prominent in the Brallier Formation just above the Burket/Geneseo Formation. Faults are seen in the form of cleavage duplexes and bedding-parallel slip accompanying flexural-slip folding. Cleavage duplexes are found in the Marcellus whereas bedding-parallel slip is more common in the overlying Mahantango Formation and further up the section in the Brallier Formation. Layer-parallel shortening decreases from greater than 50% to approximately 10% when crossing the Jacks Mountain–Berwick Anticline structural front from the hinterland portion to the foreland portion of the Valley and Ridge. Disjunctive cleavage, the primary mechanism for layer-parallel shortening, is best developed in carbonates whereas pencil cleavage is best developed in shales.
Engelder, T., Slingerland, R., Arthur, M., Lash, G., Kohl, D., and Gold, D.P., 2011, An introduction to structures and stratigraphy in the proximal portion of the Middle Devonian Marcellus and Burket/Geneseo black shales in the Central Appalachian Valley and Ridge, in Ruffolo, R.M., and Ciampaglio, C.N., eds., From the Shield to the Sea: Geological Field Trips from the 2011 Joint Meeting of the GSA Northeastern and North-Central Sections: Geological Society of America Field Guide 20, p. 17–44, doi: 10.1130/2011.0020(02). For permission to copy, contact
[email protected]. ©2011 The Geological Society of America. All rights reserved.
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OVERVIEW During the first decade of the twenty-first century, the American energy portfolio was dramatically realigned after operators in Texas learned to use horizontal drilling and massive hydraulic (slickwater) fracture stimulations to recover natural gas from the Mississippian Barnett black shale, a source rock once considered of little economic value. In 2004, the Middle Devonian Marcellus black shale of the Appalachian Basin was first tested in a vertical well using slickwater fracturing. Late in 2007, Range Resources announced that their horizontal wells in the Marcellus were producing natural gas and associated liquids at economic rates. A Penn State press release on 17 January 2008 introduced the vast economic potential of natural gas production from the Marcellus to the public (Engelder and Lash, 2008). Production from the Marcellus through 30 June 2010 validated the earlier volumetric calculations verifying that the Marcellus of the Appalachian Basin was a super giant gas field and one of the largest in the world (Engelder, 2009). Because of the economic value of natural gas in the Marcellus, this formation has become a central focus for geological research in Appalachia. This field trip visits some of the key outcrops straddling a minimum of 1420 m of the Lower to Upper Devonian section in the Appalachian Valley and Ridge with a focus on the Marcellus black shale (Fig. 1). Of particular interest is the extent to which the structural fabric in the Middle Devonian section is dependent on the sedimentary geometry of the Appalachian Basin (Lash and Engelder, 2011). Sedimentary geometry is in turn controlled by a combination of global eustasy and a more local tectonically driven sea level change (Ettensohn, 1985). The fundamental observations for this trip were laid through a century of field work and herein we weave the threads of this work together in a context of a modern understanding of plate tectonics, sequence stratigraphy, and fracture mechanics. For example, the Marcellus Formation and associated strata, consist of at least four thirdorder depositional sequences, dividing the strata into lowstand (LST), transgressive (TST), and highstand systems tracts (HST) (Fig. 2). These sequences are defined by sequence boundaries associated with the Oriskany Sandstone (The Wallbridge Unconformity; Swezey, 2002), within the Selinsgrove (Senaca) Member of the Onondaga Limestone, the base of the Purcell/Cherry Valley Limestone, and the base of the Stafford Limestone (Lash and Engelder, 2011) (Fig. 2). The outcrops of the Middle Devonian section in the Appalachian Valley and Ridge reflect Laurentian plate tectonics from deposition during the early Acadian Orogeny (ca. 389 Ma) through the Alleghanian Orogeny (ca. 265 Ma). Before 390 Ma, the southeastern margin of Laurentia was loaded by the convergence of a microcontinent, Avalonia, which had an active volcanic arc (Ettensohn, 1987). This load created the accommodation space for the Marcellus transgressions (Ettensohn, 1994). At this time, Gondwana and Laurentia were separated by an ocean basin that was closing rapidly. The Middle Devonian Eifelian and Givetian Stages are characterized by two black shale sequences
(i.e., Marcellus Formation and the Geneseo/Burket Formation) both of which will be visited during this field trip (Fig. 1). Convergence culminated at approximately 315 Ma when Gondwana and Laurentia collided obliquely and slid past each other for at least 15 m.y. (Ferrill and Thomas, 1988). The oblique slip between Gondwana and Laurentia was dextral with Gondwana slipping west relative to Laurentia. This phase of the Alleghanian orogeny is characterized by major strike-slip faults
Figure 1. Stratigraphic column of the Devonian section in the vicinity of the Juniata Culmination of the Appalachian Valley and Ridge (adapted from the AAPG CSUNA Northern Appalachian Sheet). All thicknesses given in meters (Lindberg, 1985).
Middle Devonian Marcellus and Burket/Geneseo black shales including the Brevard fault zone and other faults in the Appalachian Piedmont (Gates et al., 1988) and a joint set that is found along the length of the Central and Southern Appalachians (the J1 set; Engelder and Whitaker, 2006). By 290 Ma, Laurentia and Gondwana ceased to slip in a dextral fashion and locked at the New York Promontory. The New York Promontory served as a fulcrum for a clockwise pivot of Gondwana relative to Laurentia (Hatcher, 2002). This clockwise pivot drove Gondwana directly into Laurentia, causing the fold-thrust belt of the Central and Southern Appalachians (Hatcher et al., 1989). The Northern and Maritime Appalachians were characterized by transform tectonics with no sign of a foreland arising from a direct continentcontinent collision. The timing of the head-on collision between Africa (Gondwana) and North America (Laurentia) during the
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Alleghanian Orogeny of the Central and Southern Appalachians is poorly constrained but may have lasted as much as 35 m.y. (300 Ma to 265 Ma), depending on what geological indicator is used as a measure of this orogeny. Our field trip will cross the Appalachian Valley and Ridge by traveling from the Appalachian Plateau side of the Allegheny Front (Stops 1–2) to the middle coal fields of the Anthracite District (Stops 5–7) (Fig. 3). The trip starts along the Allegheny Front where beds are overturned, passes through the Nittany Anticlinorium where layer-parallel shortening strain is 15%, and then crosses the Jacks Mountain–Berwick Anticline structural front where layer-parallel shortening strain is greater than 50% on the hinterland side (Nickelsen, 1983). A layer-parallel shortening strain of 50% in the Marcellus is indicated by a strong
Figure 2. Gamma ray (GR; in American Petroleum Institute units) and bulk density (RHOB; in g/cm3) log typical of the Marcellus Shale and associated strata. This log is part of the suite of logs from the Appalachian Valley and Ridge that Penn State’s Appalachian Basin Black Shale Group has acquired with industrial support. LST— lowstand systems tract; TST—transgressive systems tract; HST—highstand systems tract; SB—sequence boundary; MFS— maximum flooding surface.
TERTIARY
MD.
INDIANA
12
BLAIR
20
11
30
1-2
MISSISSIPPIAN
50 MI
77°
UNION
PERRY
JUNIATA
DEVONIAN
ADAMS
CUMBERLAND
4
SULLIVAN
DAUPHIN
NO
D
MD.
ORDOVICIAN
YORK
76°
CHESTER
CAMBRIAN
LANCASTER
WAYNE
42°
MONTGOMERY
N.J.
LOWER PALEOZOIC
DEL.
41°
PIKE
75°
75°
75°
BUCKS
DELAWARE
LEHIGH
NORTHAMPTON
CARBON
MONROE
LACKAWANNA
BERKS
LUZERNE
WYOMING
SUSQUEHANNA
76°
SCHUYLKILL
LEBANON
BE UM H RT
N RLA
COLUMBIA
LYCOMING
SILURIAN
77°
N.Y. BRADFORD
SNYDER 5-7
3
TIOGA
80 KM
CLINTON
EXPLANATION
FRANKLIN
40 60
MIFFLIN 8
CENTRE
HUNTINGDON 9
78°
40
POTTER
20
10
78°
FULTON
PENNSYLVANIAN
BEDFORD
CAMBRIA
CAMERON
McKEAN
CLEARFIELD
ELK
PERMIAN
79°
SOMERSET
JURASSIC AND TRIASSIC
W.VA.
FAYETTE
WESTMORELAND
ARMSTRONG
JEFFERSON
FOREST
WARREN
79°
0
40°
PRECAMBRIAN
75°
Figure 3. The geology of Pennsylvania showing the location of field stops along the Allegheny Front (Stops 1 and 2) and into the Valley and Ridge. Dashed line indicates the approximate location of the Jacks Mountain–Berwick Anticline structural front. (Adapted from PA-DCNR Map 7; www.dcnr.state.pa/us/topogeo.)
QUATERNARY
GREENE
80°
ALLEGHENY
N.Y.
CLARION
VENANGO
BUTLER
80°
R
WASHINGTON
BEAVER
LAWRENCE
MERCER
CRAWFORD
ERIE
KE LA
IE ER
SCALE1:2,000,000
OU
40°
41°
42°
OHIO
10
NT A
0
ER IV
R
IL
MO
W.VA.
RE
WA
J.
LA
N.
DE
PH
Y.
PH IA
N.
DE L
20 Engelder et al.
Middle Devonian Marcellus and Burket/Geneseo black shales disjunctive cleavage, strain fibers about pyrite nodules, and cleavage duplexes. The second day of this trip (Stops 8–12) runs in the opposite direction across the Jacks Mountain–Berwick Anticline structural front. STOP 1. J2 (CROSS-FOLD OR DIP) JOINTS IN THE FORM OF NATURAL HYDRAULIC FRACTURES IN THE BRALLIER GRAY SHALE Brallier Formation: Chronostratigraphic Equivalent to the Genesee Group of New York Series (Eur. Stage): Middle Devonian (Givetian) Location: Howard, Pennsylvania (outcrop on north side of road along Route 150 between Milesburg and Howard) Coordinates: 40.992980° by −77.709799° (datum WGS84 spheroid) Background: Joint growth in the Middle and Upper Devonian section of the Appalachian Basin correlates with the presence of black shale (Lash et al., 2004; Lash and Engelder, 2005; Engelder, et al., 2009). Two major joint sets are found with the earlier set, J1, better developed within black shale and the later set, J2, better developed within the gray shale immediately above. In western areas of the basin where black shales are stacked, joints populate each black shale. In eastern portions of the basin where the Marcellus is the sole black shale, joint development decreases with distance above the black shale until the Carboniferous section is reached where jointing is very sparse. The correlation between jointing and black shale is largely a function of the driving mechanism for joint propagation which comes from internal pressure during maturation of kerogen to produce hydrocarbons, mainly natural gas (Lacazette and Engelder, 1992). These are natural hydraulic fractures (NHF) where tectonic stress controls the orientation of the joint set but tectonic stress is not the cause of joint propagation. Some of the best examples of black-shale– related NHF are found above the Geneseo/Burket black shale in the Finger Lakes District, New York (Fig. 4). Observations: Route 150 from Port Matilda to Bald Eagle State Park follows just south of a line of low ridges marking the position of the more resistive siltstones of the Brallier Formation. To the north of the road in several outcrops a well developed J2 joint set is seen in numerous of outcrops of the Brallier Formation (Fig. 5). The Burket Member, a black shale, is exposed just under the Brallier Formation in a small quarry near Bald Eagle State Park (Stop 2). The trip will stop at a Brallier outcrop Dbh-31-RU before stopping at Dbh-30-RU which is the small quarry of Burket black shale (Fig. 5). The general rule of thumb for joint development in Devonian black shales of the Appalachian Basin is that J1 is better developed in black shale and J2 is better developed in gray shale. Our first stop is an outcrop of Brallier sitting just above the black shale of the Burket (Geneseo) black shale, the oldest Upper Devonian black shale above the Hamilton Group. The basal portion of the Brallier tends to be finer grained with coarser turbidites appear-
21
ing farther up section (Fig. 6). We will visit the Brallier twice on the field trip with the second outcrop being higher in the section where turbidites vary in thickness up to nearly a meter (Stop 12). The difference in joint development between Stop 1 and Stop 12 is the vertical height to spacing with joints at Stop 1 having a height that far exceeds spacing. At Stop 12, the height to spacing ratio is roughly 1:1, a characteristic of well-developed mechanical beds and a characteristic of turbidite or carbonate beds interrupting shale beds. At Stop 1, the silt beds are thin ( 6%) reveals that this portion of the Marcellus is in the hot bottom section as observed on gamma-ray logs (Fig. 2). J1 joints are well developed in this portion of the Marcellus and exhibit the characteristics of NHF by passing around some large concretions within the Union Springs (McConaughy and Engelder, 1999). In general, the surfaces are not as planar as seen in outcrops of black shale in the Finger Lakes District, New York. Like the J1 joints in the Snook quarry at Antis Fort, these joints form normal to bedding. When bedding is rotated to horizontal, the J1 joints return to vertical, again a sign of a prefolding origin. Also, like the Snook quarry, the J1 joints have a relatively weak cluster. In the Finck quarry the vector mean strike for the J1 set is 061°. While clustering is weak at both Stops 3 and 4, it is noteworthy that the orientation of J1 joints on both sides of the Nittany Anticlinorium are counterclockwise by approximately 10° from the strike of J1 joints in the Finger Lakes District of New York. This is consistent with the orientation of J1 joints along the entire Appalachian chain (Engelder and Whitaker, 2006). STOP 5. CLEAVED LIMEY SHALE AT THE BASE OF THE MAHANTANGO
Figure 8. Examples of joint development in the Oatka Creek Member of the Marcellus at the Ed Snook quarry along Old Fort Road off Route 44 west of Antis Fort. Bedding is overturned at 074°/72° (strike and dip by the right-hand rule). (A) Photo taken about March 2007. (B) Photo taken September 2008 after nearly a meter of bedding, including the layer of concretions, had been ripped away.
Mahantango Formation of the Hamilton Group Series (Eur. Stage): Middle Devonian (Eifelian) Location: Sunbury, Pennsylvania (road cut along Route 147 less than 2 miles south of the intersection with Route 61 in Sunbury, Pennsylvania) Coordinates: 40.839552° by −76.806962°
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Engelder et al.
Figure 9. Examples of joint development in the Oatka Creek Member of the Marcellus at the Ed Snook quarry along Old Fort Road off Route 44 west of Antis Fort. Bedding is overturned at 082°/65°. View looking west and parallel to J1 joints. Joints plotted in present coordinates (left) and rotated to their position with horizontal bedding using a fold axis plunging 05° toward 082° with a rotation of 115° (right).
Middle Devonian Marcellus and Burket/Geneseo black shales
27
Figure 10. Left: Concretion with fibers indicating differential slip between the concretion and bedding of Marcellus. Right: In places the Marcellus is fossil rich. Psilophytes are seen at the Ed Snook quarry, for example. These are primitive vascular plants known as white ferns with both stems and branches looking like thick cylindrical pieces of grass. The picture, above, is the stem of a plant. Note the crinoids that have attached to the stem. (Swiss Army knife shown for scale.)
Background: Day 1 focuses on the Marcellus in the transition between the Allegheny Front and the Anthracite District of the Valley and Ridge. The initial two stops are along the Allegheny Front in the Brallier distal turbidites and Burket/ Geneseo black shale. The Marcellus is first encountered on the north side of Bald Eagle Ridge where rocks are vertical to overturned on the northern limb of the Nittany Anticlinorium (Stop 3). Next is a look at the Marcellus on the south limb of the Nittany Anticlinorium (Stop 4). The first four stops sit in a region where layer-parallel shortening (LPS) measures little more than that encountered within the Appalachian Plateau detachment sheet (