35-5 Rapid deglaciation of the Laurentide Ice Sheet from the High Peaks Wilderness, Adirondack Mountains, New York, USA during the Allerød Warm Interval

Session: Ice sheets, glaciers, and landscapes, oh my! (Posters)

Presenting Author:

Authors:

Abstract:

During the last glacial period, the Laurentide Ice Sheet (LIS) contained 75-85 m of global sea

level equivalent making it the largest ice sheet by volume and a substantial influence within the

climate system. Understanding the timing and rate of LIS deglaciation is of considerable

importance in associating its contribution to sea-level rise, abrupt climate change, and climate

feedbacks. Studies of LIS retreat through the northeast United States have used various

geochronometers (e.g., surface exposure dating, radiocarbon, varves) and methods to constrain

changes in the vertical and lateral components of the ice sheet. Yet, reconstructions of the LIS

in this region exhibit areas of limited geochronologic data leading to assumptions about the

character and timing of ice-sheet retreat. Here we present new 36Cl surface exposure ages from

the High Peaks Wilderness region of the Adirondack Mountains paired with transient ice-sheet

model simulations of LIS retreat through the region. Our results show full retreat of the LIS from

the region occurred within a 500 year interval at 13.5 ± 0.3 ka, consistent with the rate of

deglaciation presented in model simulations through the Adirondacks. The timing of local

deglaciation is younger than previously proposed, while remaining in agreement with

minimum-limiting radiocarbon ages indicating reoccupation of fauna and flora by ~13 cal ka. The

model simulations demonstrate low ice-flow velocities in the mountains relative to the

surrounding lowlands which may have acted as an impediment to ice retreat. These new results

shift the timing of deglaciation from the Adirondack High Peaks later to the Allerød warm interval

with implications for the response time of the ice sheet to abrupt climate warming as well as the

influence of subglacial topography on deglaciation.

Geological Society of America Abstracts with Programs. Vol. 58, No. 2, 2026

© Copyright 2026 The Geological Society of America (GSA), all rights reserved.