GLACIAL GEOLOGY OF THE SCHENECTADY QUADRANGLE 2^ 



an extensive land surface. These deposits filled the lake up to the 

 level of 420 feet. 



The overflow waters of the lake followed lines of depression 

 across the belt of moraine forming the dam. Gradually, through 

 difference in rate of erosion a single outlet stream was formed and 

 began to cut out the gorge east of High Mills. At the same time the 

 lake was drained leaving the deposits in the form of a plain, 420 

 feet in elevation. 



Alplaus creek and its .tributaries, by downward cutting and 

 meandering, have since formed broad and deep 'valleys in the de- 

 posits; while below High Mills the gorge with vertical walls of 

 rock in places 60 feet high, has been eroded out. 



