FILLING IN THE GAPS FOR LAURENTIDE DEGLACIAL THINNING IN THE ADIRONDACK MOUNTAINS, NEW YORK, USA

Anthropogenic warming has led to an acceleration in global ice sheet mass loss over the last few decades with an associated rise in eustatic sea level. Yet, considerable uncertainty exists in how the world’s ice sheets will respond to future warming and their impact on sea level. Geologic evidence of ice-sheet activity provides an opportunity to refine cryospheric sensitivity to changing climates. Various geochronometers (e.g., cosmogenic nuclide surface exposure ages) provide constraints on Laurentide Ice Sheet (LIS) deglaciation, which, during the Last Glacial Maximum (LGM), contained ~75-85 m global sea-level equivalent. While much is known about LIS margin retreat, fewer data exist for vertical constraints needed to quantify ice-volume changes following the LGM and contribution to sea-level rise. Here we present 14 new ³⁶Cl surface exposure ages from the Adirondack Mountains (ADK) of New York. Each sample was strategically chosen from a condensed spatial region of the ADK High Peak Wilderness, where elevational contrast that is largely unique to the northeastern United States exists. These data provide geologic constraints to the LIS surface over a ~1000 m range and therefore ice surface thinning rates. Our ³⁶Cl ages are paired with a high resolution (sub-km scale) ice sheet model (ISSM) to provide insight into ice sheet characteristics (i.e., basal conditions) at the LGM for the southeastern portion of the LIS.