19 Ice sheets, glaciers, and landscapes, oh my!

Glaciers and ice sheets shaped the landscape of the Northeast. Ice continues to shape the landscape of alpine and polar regions. We welcome submissions on glaciers &  ice sheets of any size, shape, age, and location.

Monday, 23 March 2026
8:00 AM - 12:00 PM
CCC, Room 26

Last Glacial Maximum Ice Sheet Buildup of the Hudson Lobe in the Northern Catskill Mountains: New Age Constraints for Glacial Lake Grand Gorge

Paper number: 19-3
Program: Technical Sessions
Time: 8:45 AM – 9:05 AM

Authors

Abstract

In New York State, ice-dammed lakes were common along the Laurentide Ice Sheet during the Pleistocene. In the Schoharie Valley of the northern Catskill Mountains, New York, a 171 km2 lake phase known as glacial Lake Grand Gorge formed when the Schoharie Sublobe blocked northward drainage of Schoharie Creek. Previous workers suggested that deltas developed along the eastern shores of glacial Lake Grand Gorge from meltwater supplied by adjacent Hudson Lobe glaciers during deglaciation.

Lidar terrain models and new geological mapping in Albany County have identified a new Westerlo Sublobe of the Hudson Lobe. This sublobe advanced over the clastic and carbonate Devonian sedimentary rocks of the Helderberg Plateau and through passes in the northeastern escarpment of the Catskill Mountains. This study evaluates stratigraphy and sedimentology of deltas and lake deposits of glacial Lake Grand Gorge to determine the source of meltwater and sediment. Detailed examination of stratigraphy from quarries, stream exposures, and new exploration borings was combined with radiocarbon and OSL geochronology to establish event stratigraphy.

Sedimentologic and geomorphic data from deltas in the Manor Kill and Platter Kill Valleys demonstrates that braided outwash was supplied directly from Hudson Valley glaciers that crossed the northeastern escarpment of the Catskill Mountains and that the Westerlo Sublobe built up as an accretionary process of ice sheet growth. New geochronologic data indicates that the lake was established by 28 ka and likely persisted to at least 22 ka. Insects and twigs recovered from drill core of lake sediments complement the OSL data and indicate (1) that the lake was present significantly earlier than previous deglacial models predict, and (2) that it existed in an ice-free area of the northern Catskill Mountains during the last glacial maximum of the MIS 2 glaciation.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2

doi: 10.1130/abs/2026NE-411299

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