674 GEOLOGY OF OLD HAMPSHIRE COUNTY, MASS. 



In the northern part, in Greenfield, the lake bottom is elevated nearly 

 to the level of the shore bench, as the lake was here shallow from the 

 beginning, and narrow, and it is covered mainly by quite coarse material. 

 Farther south, in the south of this town and in the north of Deerfield, the 

 original depth was greater, and a great thickness of clays gathered, over 

 which the flood sands were swept, as detailed in the section. (See p. 634.) 



South of the delta of Deerfield River, through the southern portion 

 of Deei-field and through Hatfield, the lake bottom is a broad, almost 

 perfectly horizontal sand plain; chosen for the base line of the Borden 

 survey as the most perfect plain in western Massachusetts. It is under- 

 lain by fine white sands, with delicate cross stratification dipping very 

 commonly about 15^ S., changing downward pretty suddenly into fine, 

 horizontal clays. This plain extends from the foot of "The Rocks" across 

 Hatfield with a height of only about 13 feet above the highest flood plain 

 of the Connecticut, and is continuous across the river in the extensive 

 plain of exactly similar character and elevation which extends from the 

 south of Sunderland down through North Hadley and the west of Amherst, 

 and, dividing on Slount Warner, sends one lobe down past its eastern base, 

 between it and the Amherst ridge, while the other entirely similar lobe, 

 which formerly skirted its western base, has been largely removed by the 

 oscillations of the river and disguised by the aliundant dunes which have 

 formed over the remaining- portion. 



One can not well cross the Amity street meadow, west of Amherst, and 

 study the lower slopes of Mount Warner and its southern prolongation with- 

 out feeling that the meadow was the bottom of a stream whose current 

 molded the sides of Warner. This hill stood like a pier in the midst of 

 the broad water, but nearer its western side, and the currents dividing on 

 it wore deepest around its northern base; and the grooves thus formed 

 extended south, widening and shallowing, being best developed at Amity 

 street — a little higher and less marked where it crosses the Northampton 

 road, but traceable like a distinct river bed for a long way south through 

 the woods, until it rises and blends with the broad jjlain in the southwest 

 part of Hadley, after the obstructing hill had been passed. 



It is plain that the western branch of this groove, occupying a narrower 

 passageway and directed toward the Holyoke notch, was the deeper, and 

 so determined the course of the main stream on the recession of the waters. 



