|2009 Portland GSA Annual Meeting (18-21 October 2009)|
|Paper No. 247-27|
|Presentation Time: 9:00 AM-6:00 PM|
LAKES, SHEAR & MULTIPLE TILLS: AN EXAMPLE OF A COMPLEX ICE MARGINAL POSITION IN THE EASTERN CATSKILLS
KOZLOWSKI, Andrew L., Geologic Survey, New York State Museum, 3140 Cultural Education Center, Albany, NY 12230, firstname.lastname@example.org, BIRD, Brian C., Department of Geoscience, Western Michigan University, Kalamazoo, MI 49008, SMITH, Colby A., Geology, New York State Museum, Cultural Education Center of the Empire State Plaza, Albany, NY 12208, KRUMDIECK, Newton W., New York State Geological Survey, New York State Museum, Albany, NY 12230, and STEFANIK, Paul, New York State Museum, Geological Suvey, Albany, 12230|
A thick (27m) exposure along a prominent ridge transverse to the
Detailed stratigraphic, sedimentologic and structural analysis reveals an uncharacteristic sequence inclusive of eight discrete diamicton units, interpreted as deformation tills interlaced with glaciofluvial and glaciolacustrine deposits. Diamictons are generally matrix supported, clast rich, overconsolidated and range in thickness from 0.24m- 7.0m. Diamictons exhibit pervasive deformation including folds, shearing, boudins and measurable fabrics.
In mid section of the exposure is a 4m thick sequence of varves composed of laminated silty-fine sand and clay. The majority of varves within the exposure do not display the deformation observed within the diamictons that occur above and below the varve section. Oversized clasts as large as 0.3m occur within the varve units and some couplets contain sandy horizons that contain gravel sized material. Diamictons below the varves display recumbent folds, clast plowing and boudins. The lower most diamictons contain a higher percentage of crystalline lithologies whereas diamictons in the upper section display a higher percentage of local Devonian sedimentary rocks.
The valley morphology upstream from the Willow Moraine displays a flat low relief plain 0.75km in width composed of sand, downstream from the moraine the valley develops a narrow 0.15 km wide sinuous expression, armored with cobbles and boulders. The upstream valley is interpreted as a proglacial lake basin that developed with ice retreat. Assignment of the varves is complicated by the existence of another large proglacial lake in the Esopus Creek valley the trunk stream to the Beaver Kill. The Willow Moraine is consistent with a model of active dynamic ice behavior. Evidence of valley glaciers have been proposed for other locations in the Catskill Mountains at present there is not enough data to substantiate if the Willow Moraine developed as an independent valley glacier or as a sublobe of the Hudson Lobe continental ice.
2009 Portland GSA Annual Meeting (18-21 October 2009)
General Information for this Meeting
|Session No. 247--Booth# 176|
Quaternary Geology (Posters)
Oregon Convention Center: Hall A
9:00 AM-6:00 PM, Wednesday, 21 October 2009
Geological Society of America Abstracts with Programs, Vol. 41, No. 7, p. 641
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