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EMERGING VIEWS OF ESOPUS BASIN GLACIAL HISTORY
Rich described Esopus basin deglaciation with “The key...seems to lie in the concept of general stagnation...” and noted “The valley of Esopus Creek...has thick deposits of lake clay, over most of which is a veneer of till.” Thus, the enigma is a basin covered with stagnant ice yet also filled with lake clay during deglaciation.
We proposed the model of a proglacial basin-wide lake ahead of advancing ice (De Simone & Rayburn 2012, Sandstrom et al 2012, Kiser et al 2011). This lake deepened as Rich’s outlets were successively blocked by ice. Thick laminated silt-clay filled the basin. Ultimately, ice overrode the lake, deformed the top of the lacustrine sediment & incorporated it into a red clay-rich till. Clay mineralogy indicates the till was derived from the underlying lacustrine unit. Till overlies clay on the valley floor; clay is not a mapping unit & it’s exposed only in stream banks & slumps (Rich 1935, De Simone 2009).
After the LGM, stagnant ice choked the Esopus basin. Hudson lobe retreat successively uncovered Rich’s outlets but only localized shallow lakes formed amid stagnant Esopus ice. Rich’s Bushnellsville kame terrace/delta (1320ft) records deposition in one such small lake. Sandy shallow water lacustrine sediments accumulated in many portions of the basin where local lakes existed.
Ice retreated at least to the north flank of the Catskills & perhaps approximately to LaFleur’s Tannersville ice margin. Meltwater flowed through Stony Clove Notch (2070ft) & deposited gravel-sand outwash graded distally to shallow sandy lacustrines in one of these local lakes. A readvance overrode these shallow water lacustrines & deposited a second red, clay-rich till. The timing & extent of this readvance remains problematic. Details of the Esopus basin stratigraphy can be found in this volume (Staley et al 2013).