CHAPTER XVI. 

 THE GLACIAL PERIOD. 



THE PRESENT ROCK SURFACE AND THE AMOUNT OF GI.ACIAL AND 

 POST-GLACIAL MATERIAL ON THE SAME. 



If the unconsolidated deposits — sands, clays, and gravels — were 

 removed from the valley we should see a rocky floor, everywhere almost 

 the exact surface upon which the ice last lay, except where, from the north- 

 ward-facing cliffs of the Hol}-oke range, the frosts have since eaten into the 

 much fissured trap and formed the talus of sharp fragments which rests 

 against its base, and in limited areas where the streams flow on rocky beds. 



The whole horizon would be unchanged. The high ridge which stretches 

 south from Mount Toby, and upon which North Amherst, Amherst village, 

 and South Amherst are built, would be little changed until, coming south- 

 ward, we reached Mount Pleasant, the southern portion of which would be 

 lowered to the level of the street at its western base, and College Hill, 

 Mount Doma, and Castor and Pollux^ would also be absent. A ridge of 

 rock would also stretch southward from Mount Warner, much below the 

 present surface. The three depressions which, running north and south, 

 bound these two ridges, would be mvicli deepened, the East street depression 

 by at least 60 feet; the middle one, separating the two rocky ridges, to an 

 unknown depth; the western, in which the Connecticut now runs, to at least 

 110 feet below low Avater of that river, and thus down somewhat below 

 the level of the sea. On the west of the river, in Northampton, the changes 

 would be more extensive, as south of Elizabeth Rock and Roberts Hills and 

 east of Loudville all the elevated country. Round Hill, the Hospital Hill, and 

 the rest, would be removed, and the rock floor would be found everywhere 

 down near or below the present level of the river, except along Mill River 

 near the West street bridge. Under the Northampton meadows it may 

 well be a hundred feet lielow the river level. I have already indicated 

 the probable condition of the valley when the ice began to work upon it, 



' Names given by President Hitchcock to drumlius south of College Grove and north and south 

 of South Amherst. 



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