When ice meets bedrock: variation in regional lithology as a control on the size variation of the Finger Lakes in Western New York

The Finger Lakes are a set of eleven elongate lakes in Western New York that were carved by glaciers at the edge of the Laurentide Ice Sheet and are one of the most iconic glacial features in the world. Despite their common genesis, the lakes vary greatly in their length and depth. This study investigates the hypothesis that variation in the regional bedrock, rather than differences in ice flow patterns, may have been responsible for this size variation, with the longest and deepest lakes occupying an optimal location in easily erodible bedrock. To test this hypothesis, a simple one dimensional (1D) numerical model of glacier advance and erosion was used to find that lithologic changes alone can explain first-order Finger Lakes size differences using three lakes as case studies. Results also show that lithology can explain the observed bathymetric morphology of the lakes, with the deepest points of each lake occurring approximately two-thirds of the way down the trough from the northern shore. Regional lithology may thus provide an explanation for the dimensions and profiles of the Finger Lakes with likely implications for other glacially carved landscapes.