1 6 NEW YORK STATE MUSEUM 



lake area, instead of leaving the plains vrith steep fronts more than 

 loo feet high. A significant fact is that the low plains bordering 

 the lake on the west and south have the same height as those about 

 Round lake, namely, 200 to 220 feet. 



Probably the lake has been elevated and enlarged by the land 

 tilting and the lifting of the northward outlet through Fish creek. . 



Professor Woodworth recognized the e\4dences of ice occupation 

 of the Round and Saratoga Lake basins, but attributed the fact to 

 the slower melting of the western side of the Hudson ice lobe (4, 

 pages 135-36). He says: '' The ice remained longer over the 

 depressions occupied by Saratoga and Round lakes than it did in 

 the Hudson valley, immediately east of this district. The large 

 streams coming into the Hudson valley from the open ground on the 

 east probably favored the melting of the glacier more rapidly on the 

 side where their waters coursed along the ice margin." But the ice 

 margins here were not swept by rivers but laved by deep, open 

 waters. The lake basins were occupied by ice blocks detached from 

 the glacier front, and more or less protected by glacial and delta 

 drift. And the blocks of ice persisted while the ice front receded 

 unkno\\Ti miles to the north. 



ORIGIN OF BALLSTOX LAKE 



This lake Hes in the rock channel of the great Iromohawk river. 

 If it were qtdte shallow it might be thought due to the differential 

 northward uplift, along with the vegetal accumulation as a swamp 

 at the outlet. But in a letter to the writer Professor StoUer says: 

 " The depth is 109 feet at a point about 400 feet from the southern 

 end of the lake. Farther to the north, about half a mile from the 

 southern end, the depth measured 55 feet." 



As this lake lies along a line of faulting (see Gushing. 8, page 105) 

 it may possibly be attributed to postglacial dislocation and be called 

 a " graben." The earlier faulting possibly determined the course 

 of the river flow. . The subject desen'es further study. 



ABSE^XE OF :vIARIXE FOSSILS 



Because marine fossils have not been found in the water-laid 

 deposits of the Hudson valley, some geologists have regarded the 

 ancient waters as glacial, not as confluent with the sea. But marine 

 life should not have been expected, for some consideration of the 

 physical conditions shows that salt-water organisms could not enter 



