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 ]\Iills. 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. 



