HOW TO RECOGNIZE A DEAD ICE SINK (DIS): NOT YOUR ORDINARY STAGNANT ICE ENVIRONMENT

Retreat of the Laurentide ice sheet from the high relief Appalachian Plateau of central NYS led to the formation of valley ice tongues in all major valleys. Detached, massive ice blocks sufficiently large to occupy the full valley floor were occasionally stranded in aggrading outwash as the ice front retreated, thus leaving ice blocks partially buried in valley train.

With continued retreat from the northern edge of the Plateau, meltwater was eventually diverted to the Mohawk Valley thus restricting downvalley stream flow to meteoric discharge. Consequently, depressions over progressively down wasting ice blocks eventual development in size into enormous kettles that occupy the entire valley floor width. The mechanism of formation and subsequent sediment accumulation yields the name “Dead Ice Sink”.

The resulting landform may resemble a lacustrine plain but differs by being confined upvalley and down by valley train segments. Consequently, subsurface deposits collapsed by ongoing ice block downwasting, may include limited segments of lacustrine fines, fluvial sand and gravel and inwash. Such an active sedimentary environment is bound to result in complex groundwater aquifers of limited lateral extent.