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Seneca Lake, Our Focus
Erosion by the glaciers cut into a significant portion of the Devonian strata and it may have penetrated as deep as the evaporites, especially in Seneca Lake. Products of this erosion are to be found in the Valley Heads Moraine south of the lake and in the thick valley-fill further south under Horseheads and Elmira. The rock surface under the lake is buried deeply. Geophysical studies on the lake and the results of drilling at Watkins Glen and Geneva show that a thick mass of glacial deposits sits on and fills the rock valley which forms Seneca Lake. Each basin has as much as 150-200 meters of glacial-lake sediments. This entire mass was in place by 12,000 years ago. Since then, the lake basin has been tilted south slightly exposing lake sediments near Geneva. At the same time, deltas were built at several locations along the shore and a massive fill of stream deposits was poured in to form both the alluvial fans on which the villages of Watkins Glen and Montour Falls are built and the swamp between them. At the same time the open lake has received a "quiet rain" of mud and an occasional pulse of coarser sediments from storm-related processes. Up to 10 meters of postglacial muds have accumulated in Seneca Lake some 12,000 years ago. Along with the physical characteristics listed below, modern Seneca Lake is thermally stratified over part of the year. The thermal structure and its variation both over time and from place to place are of great interest if we are to understand the biology and chemistry of the lake. Plants, animals and various chemical constituents will be distributed in part as a response to the thermal structure. Physical Characteristics of Seneca Lake Drained by the Seneca River (NYS Barge Canal, NE corner)
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Like all of the Finger Lakes, Seneca is in a valley carved by Pleistocene glaciers. The events that shaped the lake basin had accomplished their work by 12,500 years ago. Since then the region has remained about as we see it today. The Seneca Lake Basin, like the Cayuga Lake Basin east of it, is
a major valley which penetrates far south into the Appalachian Plateau. It is developed in Devonian sandstones and shales which have been slightly folded and broken by faults in a few places. A few hundred meters below the Devonian rocks are Silurian carbonates, shales, and most important, evaporites. The evaporites are mainly halite (rock salt). 