GLACIAL GEOLOGY OF THE SCHENECTADY QUADRANGLE 29 



of ice, glacial waters swept across the floor of the Glenville basin, 

 along the foot of the Glenville hills, and southward to the Mohawk 

 channel. These waters deposited sands over an already till-covered 

 area, thus forming the surface materials of mixed composition — 

 sands or clayey sands of loose texture, with cobbles and boulders — 

 of the southeastern portion of the town of Glenville. 



Glacial till more or less washed and eroded by powerful cur- 

 rents of water, boulders mostly of large size. The vicinity of 

 East Line in the northern part of the sheet exhibits in its typical 

 development the glacial till as modified by powerful currents of 

 water. The surface of the country is marked by a general even- 

 ness or absence of hilly features. It is thickly strewn with boulders 

 and large cobbles. The soil or mantle of materials covering the 

 bedrock, is generally thin, with frequent exposures and outcrops of 

 rock. The soil is generally clayey, evidently consisting partly of 

 till clays and partly of residual clays from local rock detritus. 



Features and materials of like description mark the several water- 

 courses that radiate from the East Line vicinity. In the valley of 

 Drummond creek, flowing to the northeast, and in the valley and 

 on the slopes of Mourning kill, flowing north, and of Anthony kill, 

 flowing southeast across the Round lake depression, evidences of 

 the washing and eroding effects of moving flooded waters are definite 

 and unmistakable. In the last named valley, in the sec- 

 tion extending from near East Line to^ Round lake, the floor and 

 lower slopes have been stripped of all the till except large boulders 

 which now lie on the surface of rock. On the floor and slopes of 

 the Round lake depression the till shows eroded and water-swept 

 surface features. 



The three glacial watercourses just noticed were branches of a 

 more general watercourse occupying the Ballston channel. The 

 evidences are of the same nature as already described. The 

 region north of Ballston lake to East Line and on either side of the 

 northern end of Ballston lake is strewn with boulders and shows 

 water-swept surface features. The floor of the channel farther to 

 the south, near the head of the lake, is neither eroded till or worn 

 rock surface, partly covered with rock detritus. Similar features 

 characterize the southern end of the channel except that on its 

 western slope erosion took effect in the Lake Albany deposits and 

 not to the extent to expose the underlying till. 



