THE BELCHERTOWN AND MOUNT TOBY NOTCHES. (363 



Just at the north Hne i»f H(>l\()ke the eastern trap ridge sinks below 

 the level of the lake, and over most of the town a g-reat body of till rises 

 much above its level, and in this the lake cut back a broad terrace flat, and 

 where these drift deposits sank below the level of the lake the latter spread 

 its sands broadly across Holyoke and West Springfield. From the north 

 line of Holyoke the influence of the great body of sand sent clear across 

 the basin from the Chicopee Eiver becomes apparent, and although there 

 was no drainage down the trap slope on the west, and the till beneath was 

 very largely made up of Triassic shale, the gneissic sands fi'om the east of 

 the basin extend out over the till along the line indicated. They bring a 

 broad area nearly up to the level of the high terrace, because it was ([uite 

 near that level before; and south of the Westfield River, in Agawam, the 

 terrace expands to nearly the width of the town, largely for the same 

 reason. It was here, of course, somewhat reenforced by material brought 

 through the notch of the Westfield River, but I question if much came that 

 way, as the source of the supply in the Westfield basin was across on the 

 west side, and the sands were in the main swept south. I think more came 

 south over Ashley's pond and west from the Chicopee River, and that the 

 difference of level of the high terrace here and in the Westfield basin is 

 almost wholly owing to a deficit of material in Agawam and West Spring- 

 field. Toward the river in Agawam the sands come to be of great volume, 

 and they once extended across to meet those of Longmeadow, and the lake 

 was in this part well filled uj) when the recession of its waters began. 



THE SIMILARITY OF THE BELCHERTOWN NOTCH TO THE NOTCH EAST OF MOUNT 



TOBY. 



I have already shown (p. 584) how the ice in the Montague basin, 

 abutting against the eastern margin of the basin and against the northeast 

 shoulder of j\Iount Toby, turned the waters of the Locks Pond Brook south 

 into the gorge between Mount Toby and the high ridge of crystalline rocks 

 in the west portion of Leverett, and how these waters cut a watercourse, 

 still well defined, through the gorge and sent out a broad delta — the present 

 South Leverett plain — into the Hadley basin. Just so the waters of the 

 Pelham brooks flowed south from the Hadley basin into the Springfield 

 basin tlu'ough the Belchertown notch and spread the long reaches of sand 

 westward down the present course of Bachelors Brook and south to Lvidlow 

 Mills. 



