Subsurface geologic investigations of New York Finger Lakes: impliations for Late Quaternary deglaciation and environmental change (GSA Special Paper 311)

Subsurface Geologic Investigations of New York Finger Lakes: Implications for Late Quaternary Deglaciation and Environmental Change Edited by Henry T. Mullins and Nicholas Eyles

PIIPER 311

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Library of Congress Cataloging-in-Publication Data Subsurface geologic inve tigation of New York Finger Lakes: implications for Late Quaternary deglaciation and environmental change I edited by Henry T. Mullins and Nicho.las Eyles. p. em. -- (Special paper ; 3ll) Includes bibliographical references and index. fSBN 0-8137-2311-6 I. GlaciaJ epoch--New York (State)--Finger Lakes Region. 2. Geology--New York (State)--Finger Lakes Region. 3. PaJeoclimatology--Holocene. 4. PaJeoclimatology--New York (State)--Finger Lakes Region. I. Mullin , Henry T. II. Eyles, N. ill. Series: SpeciaJ papers (Geological Society of America) ; 31 I. QE697.S898 1996 551.7'92' 09747--dc20

96-35721 CIP

Cover: Satellite photograph of New York Finger Lakes taken March 23, 1973 (ERTS-1243- 15244-5). Large lake in upper left-hand comer is Lake Ontario. Data available from U.S. Geologica] Survey, EROS Data Center, Sioux Falls, South Dakota. 10 9 8 7 6 5 4 3 2 I

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Geological Society of America Special Paper 311 1996

Seismic stratigraphy of the Finger Lakes: A continental record of Heinrich event H-1 and Laurentide ice sheet instability Henry T. Mullins Department of Earth Sciences, Heroy Geology Laboratory, Syracuse University, Syracuse, New York 13244 Edward J. Hinchey ERM-Northeast, 5788 Widewaters Parkway, Dewitt, New York 13214 Robert W. Wellner* Department of Geology, University of Alabama, Tuscaloosa, Alabama 35487-0338 David B. Stephens Worcester Academy, 81 Providence Street, Worcester, Massachusetts 01604 William T. Anderson, Jr.,* and Thomas R. Dwyer* Department of Earth Sciences, Heroy Geology Laboratory, Syracuse University, Syracuse, New York 13244 Albert C. Hine Department of Marine Sciences, University of South Florida, St. Petersburg, Florida 33701

ABSTRACT Seismic reflection surveys of 8 of the 11 Finger Lakes of central New York State have documented the deep (as much as 306 m below sea level) glacial scour of these lake basins and their subsequent infill by thick (up to 270 m) unconsolidated sediment. Drill data indicate that sediment infill occurred rapidly during a short interval between ~14,400 and 13,900 14C yr ago, coeval with Heinrich event H-1 when large volumes of icebergs and meltwater were discharged into the North Atlantic during an unstable phase of the Laurentide ice sheet. Six acoustically defined depositional sequences beneath the lakes, correlated with drillcore and piston core samples, record the infill history of the Finger Lakes during the late Wisconsin. Depositional sequence I is equivalent to thick, water-laid sands and gravels of the Valley Heads moraine deposited ~14.4 ka. During retreat of the ice margin from its Valley Heads position, subglacial meltwaters transported large volumes of fine-grained sediment into the Finger Lake basins (sequences II and III). Sequence IV records a phase of high-level proglacial lakes when ice blocked northern outlets of the Finger Lakes and fine-grained sediments continued to be transported into the basins from the north. An abrupt drop of proglacial lake levels and a drainage reversal is recorded by sequence V when sediments first began to enter the Finger Lakes from the south following retreat of the ice margin past the northern outlets of the lakes. The well-known modern glens and waterfalls of the Finger Lakes region formed at this time when lateral streams adjusted to dramatically lowered *Present addresses: Wellner, Exxon Production Research Company, P.O. Box 2189, Houston, Texas 77252-2189; Anderson, Geological Institute, Swiss Federal Institute of Technology (ETH), Zurich, Switzerland; Dwyer, Blasland, Bouck and Lee, Inc., 6723 Towpath Road, Syracuse, New York 13214. Mullins, H. T., Hinchey, E. J., Wellner, R. W., Stephens, D. B., Anderson, W. T., Jr., Dwyer, T. R., and Hine, A. C., 1996, Seismic stratigraphy of the Finger Lakes: A continental record of Heinrich event H-1 and Laurentide ice sheet instability, in Mullins, H. T., and Eyles, N., eds., Subsurface Geologic Investigations of New York Finger Lakes: Implications for Late Quaternary Deglaciation and Environmental Change: Boulder, Colorado, Geological Society of America Special Paper 311.

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H. T. Mullins and Others local base levels. Radiocarbon dates across the sequence V/VI boundary indicate that proglacial lake levels dropped ~13.9 ka. Depositional sequence VI represents thin (