THE MILL EIVEE DELTA. 639 



The southern portion of tlie deha is composed of the contlucnt 

 deposits of Mill River and the north branch of the Manlian. The o-reat 

 glacial lake in Westhanipton (p. 594) served as a catchment basin for 

 sands which were carried ultimately by Roberts Meadow Brook and the 

 Manhan to augment tlie high terrace at this point. While the sands in 

 Northampton are in many beds clear gray, showing under the micro- 

 scope many rounded grains of black mica-schists like those of Goshen 

 and Chesterfield, in others they are reddish from the abundance of garnet 

 grains in them, both peculiarities indicating their origin from the garnetif- 

 erous mica-schists in the drainage area of Mill River. The sands of the 

 southern portion of the plain are more largely granitic and are derived from 

 the great granitic area of Westliampton. This may be taken as one of the 

 proofs of the assertion that the high terrace was mainly brought in from the 

 sides of the basin. The great sand plain is continued across to the North 

 Branch, is in all this distance more than a mile wide, and sinks in several 

 great terraces to the clayey lake bottom at Easthampton, and as it nears 

 the south line of Southampton it enters the western of the thi'ee passages 

 by which the waters passed out upon the Westfield plain, and just on. the 

 town line it received tlie abundant deposits of the southwest branch of the 

 Manhan at Russellville, and across the basin since eroded by this stream 

 it was plainly continuous with the north end of the Westfield plain. 



Just where the western channel widens by the dropping down of the 

 hill east of East Farms into this broad, open plain the abundant contril^u- 

 tions of the branch of the Manhan last mentioned were received and spread 

 clear across the channel, up nearly to the normal high terrace level — the 

 deep water of the lake bottom shallowing- southward in the channel and 

 coming to an end just opposite the mouth of the branch, and marking out 

 thus the channel whereby, on the recession of the waters, the Manhan was 

 compelled to take a com-se north across Southampton and Easthampton to 

 join the Connecticut at the head of the oxbow. 



THE LAKE BENCH ON THE EAST SIDE OF THE HADLEY LAKE IN LEVERETT AND 



AMHERST. 



Through the Narrows in Sunderland the bench (Ish) is well marked 

 along the west slope of Mount Tob}', and turning the corner of the mountain 

 it rests against its south side. It is characterized by fine sands in great 

 quantity, dependent upon the fact that the region is far from the mouth of 



