GLACIALLY VARVED SEDIMENTS AS CHRONOMETERS FOR LOCAL GLACIAL LAKES IN THE CATSKILLS, NEW YORK

The presence of varved lacustrine sediments in Stoney Clove and Beaverkill Valleys, both tributaries of Esopus Creek, is consistent with previous interpretations that Esopus Creek held a proglacial lake dammed by the Hudson Lobe of the retreating Laurentide Ice Sheet. However, whether the varved sediments are the result of alpine glaciers or small local lobes of the Laurentide Ice Sheet has yet to be resolved along with the age and duration of the ice-dammed lake.

Examination of a stream cut along the Beaverkill contains 92 varve couplets conformably overlying diamicton and underlying multiple diamictons. Correlation of the Beaverkill varve record to the New England Varve Chronology (NEVC) provides not only chronological constraint on the lake's presence but also provides information regarding the nature of glaciation in the Catskills at this time. Coupling the 200 m minimum ice thickness of the Hudson Lobe where it dammed Esopus Creek with the terminal location of the Hudson Lobe known, due to the NEVC, yields an estimate of surface slope which can be projected northward to determine which passes (if any) Laurentide ice overtopped at this time.