Evidence of An Ice-Dammed Lake and Laurentide Readvance Upper Susquehanna Valley, New York State

Abstract

Landforms and well logs document a system of ice-contact and proglacial lakes in the upper Susquehanna valley during Laurentide Ice Sheet retreat from the Appalachian Plateau, central New York State.  Recessional moraines formed dams for all lakes, except a newly revealed “Ancestral Goodyear Lake” retained behind an ephemeral ice dam stranded at Colliersville.  A prominent dead-ice sink currently occupies the valley floor at the dam site Ancestral Goodyear Lake held a stable lake level at 1360 feet as represented by thick lake sediments perched in water well logs on the valley wall above Goodyear Lake.  A deltaic terrace at 1250 feet in the same vicinity marks a second, lower lake strand.   In addition, water well logs on the adjacent Portlandville Moraine contain lake sediments bound above and below by ice-contact material deposits thus demonstrating a Laurentide readvance that subsequently dammed the valley to form Glacial Lake Milford as part of the Susquehanna Lake System.