542 GEOLOGY OF OLD HAMPSHIRE COtWTY, MASS. 



under discussion. The latter differs from the former also in the origin of 

 its material. On the east the Ijowlders, except the abundant far-traveled 

 quartzites, are mostly from Mount Toby and the granite south of it. I 

 have rarely found a piece of the spangled mica-schist of the great western 

 range, although the bowlders of psilomelane and yellow cavernous jasper 

 found across Amherst seem certainly to have come from the locality in 

 Conway on the northwest. On the west all the rocks to the north and west 

 are abundantlv represented by large bowlders, and very large masses of the 

 Vermont quartzites are also abundant ; one taken from near D. Deuniston's 

 now adorns the old Whitney homestead, on King street, in Northampton, 

 and is about 6 feet in diameter.^ I have been inclined to connect the excep- 

 tional coarseness and abundance of the subglacial debris gathered here with 

 the peculiar direction of motion impressed upon the lower portion of the ice 

 by the trend of the great valley. As the ice moved toward the valley from 

 the northwest it came upon its western rim well charged with bowlders 

 from the area it had crossed, and was below deflected southward by the 

 trend of the valley, and still farther deflected to the west of south and 

 obstructed bv the transverse Holyoke range, and its morainic material was 

 gathered in a sort of eddy imder the western cliff's or swept southward in 

 the valley, and so failed to reach the eastern side of the basin. 



DISTRIBUTION OF THE COAESE VALLEY TILL WEST OF THE EIVEB. 



The most northerly exposure of the bowlder clay in the river side is at 

 the westernmost point of the great Hadley bend, where the river has worn 

 into it, and the bowlders, accumulating upon the shore, have formed a natural 

 "riprap" and thrown the current across against the Hadley side, where it 

 will in time cut off the point of the bend and leave its present channel. 



This exposure seems to be the northern end of a long ridge or series of 

 drumlins which runs in a general way southward across Northampton, 

 mostly covered by the later sands. It is exposed on Slough Hill, west of 

 the north end of King street, and deeply cut into by the Canal Railroad at 

 the Black Pole bridge. Its further prolongation, Round Hill, is a mass- 

 ive drumlin. Under the Forbes Library, Smith College, and the asylum 

 the bowlder clay rises to the surface and reaches just the same level as the 

 surrounding sands which form the level surface of Elm street. These two 



' It has been placed over the grave of Prof. Josiah D. Whitney, late professor of geology in 

 Harvard University. 



