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ANCIENT WATER LEVELS OP CHAMPLAIN-HUDSON VALLEYS 175 



Chapter 8 



LAEGER GLACIAL LAKES OF THE CHAMPLAIN AND 



HUDSON VALLEYS 



LAKE ALBANY 



The preceding descriptions of the successive stages of frontal 

 and marginal deposits of .the shrinking ice sheet and the attendant 

 evidences of local water bodies within the Hudson valley make 

 it evident that as the ice front retreated from the terminal 

 moraine, bodies of water stood at the ice front increasing in length 

 northward as the ice withdrew in that direction. Doubtless at 

 many of these stages the water in front of the ice might justifiably 

 be denominated a lake regardless of the relation to sea level. If 

 the land were at the same level as now the outpour of fresh water 

 would have excluded the salt and made the conditions those of 

 an estuary or lake; with the land 100 feet lower so as to bring 

 the deltas and terraces at Peekskill south of the Highlands at 

 sea level the same conditions would have held; if for any geo- 

 graphic reason the entire southern Hudson valley were above 

 sea level at that time lacustrine rather than estuarine conditions 

 would have prevailed. These considerations hold good also for 

 the conditions in front of the retreating ice sheet as far north as 

 the vicinity of Poughkeepsie at least. But north of Staatsburg 

 and thence northward throughout the Hudson valley there is a 

 record of continuous lacustrine conditions for a time marked by 

 beds of clay and marginal deltas which indicate typical lacustrine 

 conditions in the total absence of marine fossils from the beds 

 deposited at this time. To this body of water whose clays were 

 early designated the ^'Albany clays " by Ebenezer Emmons, no 

 name is so appropriate as Lake Albany. 



E. Emmons^ wrote " the Albany clay, or as it is in other places 

 called Post-tertiary clay," in 1843, long antedating the name 

 Albany as used in the geology of Texas.^ He regarded the clays 



' Natural Hastory of New York, division 5, Agriculture. 1846. 1 :260. 

 ^U. S. Geol. Sur. Bui. 191, p.42. 



