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NEW YORK STATE MUSEUM 



but south of this latter named point there is no trace of deposits 

 so late as this stage in the glacial retreat now recognizable above 

 the summit line of the walls of the Hudson gorge. It is to be 

 inferred therefore 'that Lake Albany had its southern limit some- 

 where in the vicinity of Rhinebeck and Rondout and that south 

 of that point the surface of the rock terraces were then and have 

 ever since been above the level of standing water. 



The shore lines of Lake Albany, determined by the hight of 

 marginal deltas, now rise to the north at a somewhat steeper 

 rate then the land on the south of the Highlands, but from New- 

 burg northward for several miles there is great discrepancy in 

 the level of deltas marginal to the gorge, some of the terraced 

 deposits being of a character and elevation to suggest that the 

 water level varied greatly from time to time. On the whole the 

 deltas from Rondout northward to Albany appear to lie in a 

 tilted plane which, if continued southward, passes below that in 

 which the deltas from the Highlands southward lie. This is 

 interpreted to mean that, as time went on, the detritus in the 

 lower Hudson gorge and about its mouth, in and about the 

 terminal moraine, was swept away by powerful currents lower- 

 ing the level of the waters about the ice margin. This of course 

 could only take place if the land were far enough above sea level 

 to render the water levels in the Hudson valley independent of 

 the control which would be exerted by a submergence in the sea. 

 The facts seem to indicate that the land was so far tilted down 

 on the north and up on the south that Lake Albany, held in by 

 the ice front on the north, was caused to spread over the rock 

 terraces in the upper Hudson valley while an outlet for its waters 

 was found through the gorge on the south of Rhinebeck below that 

 at which the sea stands today. 



For a time the waters of Lake Albany extended northward over 

 the Fort Edward district, covering the lower portion of the 

 plateau about Fort Ann; and thence, connecting through the 

 narrow defile of Wood creek, united with a glacial lake which was 

 extending northward in the valley of Lake Champlain pari passu 

 with the retreat of the ice from that valley. The attitude of the 

 land from Lake Champlain southward to the region of Lake Albany 

 was now that of depression on the north so that the floor of Lake 



