GLACIAL GEOLOGY OF THE COHOES QUADRANGLE 47 



ancient valley a falls developed which, through recession, formed 

 the present falls and gorge of the Mohawk at Cohoes. 



The stage of flooded waters in the MohaWk valley lasted until 

 the general ice sheet had retreated to the north so far as to open 

 a passage for the overflow waters of the great interior lakes north 

 of the Adirondack region, thus diverting the outlet to the sea from 

 the Mohawk valley. 



Whether flooded waters continued for a still longer time in the 

 Hudson valley depends upon whether the northern outlet of the 

 great lakes, when first opened, connected with the sea through the 

 St Lawrence basin as now or, for a time, found a course to the sea 

 through the Champlain-Hudson valley. Assuming the latter case, 

 there is no evidence that the flooded waters ever rose to a level 

 higher than the foot of the clay bluffs bordering the present valley 

 floor of the Hudson. 



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