PHOENICIA MAPPING SUGGESTS ALTERNATIVE GLACIAL HISTORY

Rich’s (1935) classic work represents the seminal volume on the last glaciation of the Catskill Mountains. Phoenicia quad mapping begun in 2009 continued with Rayburn’s REU students (Carey et al, 2011, Kiser et al, 2011, Sandstrom et al, 2012) who identified new exposures there & in surrounding areas.

Mapping confirmed the Esopus Valley floor is blanketed with thick red till. Very little clay is exposed except in fleeting stream bank cuts, typically beneath fluvial terraces. Cadwell (1986) showed extensive kame moraine & outwash. Rich showed minor outwash and kame deposits. The valley floor is here mapped as multiple Holocene fluvial terraces that are incised through a thick till blanket. There is no outwash & very little kamic sediment. A red clay-rich diamicton remained a puzzling unit until further work with REU students. We learned it is the basal facies of a red till that overlies lacustrine silt-clay. These lacustrines are widespread beneath the Esopus Valley floor (Carey et al, 2011). The till/clay contact shows deformation consistent with ice advance (Sandstrom et al, 2012, see next booth).

Where’s the deep water lacustrine sediment facies from Rich’s Peekamoose & Shandaken lakes? Perhaps these lakes didn’t exist during deglaciation but were large proglacial lakes ahead of the advancing Late Wisconsinan ice (Kiser et al, 2011). The lakes became deeper as the Hudson-Champlain lobe advanced, first blocking Wagon Wheel Gap & then Peekamoose Gap. Once ice advanced from the North through Stony Clove, Deep Notch & Grand Gorge into the Esopus basin, lacustrines were overridden & red till was deposited. During deglaciation, the Esopus basin was choked with stagnant ice; local lakes existed where isolated kame terrace & deltaic sediments accumulated as at Bushnellsville (Rich, 1935) & Big Indian Hollow (Smith, 2010). Active ice remained only in Beaver Kill & Little Beaver Kill Valleys (Kozlowski, 2009).