328 THE CANADIAN NATURALIST. [Vol. viii. 



The boulders which are contained in the upper till, or which 

 lie upon its surface, are of all sizes up to ten feet, or rarely even 

 twenty or thirty feet, in diameter ; and in this state, they have 

 nearly all been transported southward from their native ledges. 

 Where an outcrop of rock is so peculiar that its boulders cannot 

 be confounded with those from other ledges, we may trace them 

 southward or south-eastward, but not in other directions. They 

 are abundant near their source, and diminish in numbers and 

 size as we advance. The till of New Hampshire contains 

 boulders which are thus known to have travelled a hundred miles. 



The distribution of the till in this State and in eastern Massa- 

 chusetts is quite irregular. Sometimes no considerable accumu- 

 lations of it are seen for several miles, and the ledges lie at or 

 near the surface. Elsewhere the till occurs in large amount, 

 covering the ledges, which are scarcely exposed over some whole 

 townships near the coast. Wherever it is found plentifully, it is 

 to a large extent massed in peculiar oblong or sometimes nearly 

 round hills, which usually have quite steep sides and gently 

 sloping rounded tops, presenting a very smooth and regular con- 

 tour. These hills are of all sizes up to one-third or one-half mile 

 long, with two-thirds as great width ; and their longest axis is 

 most frequently north-west to south-east, coinciding nearly with 

 the current of the ice sheet. Their height varies from forty or 

 fifty to two hundred feet. These accumulations of till are very 

 prominent near the coast, where they sometimes occupy nearly 

 the whole territory for many miles, while adjoining areas on each 

 side may be almost destitute of surface deposits, showing only 

 naked, striated ledges. 



About Winnipiseogee lake, which is 500 feet above the sea, 

 beds of stratified clay are often found underlain and overlain by 

 till. The clay is free from pebbles, and well suited for brick- 

 making. It varies from five or ten to thirty feet in thickness, 

 and occurs at various heights from the level of the lake to three 

 hundred ieet above it. The overlying till is from two or three 

 to ten or fifteen feet in thickness, wholly unstratified and very 

 coarse, containing numerous boulders, which may be five or six 

 feet in diameter. These remarkable clay beds were probably de- 

 posited, where drainage was obstructed, in hollows melted under 

 the margin of the departing ice-sheet. This lake basin lies 

 at the south side of the White Mountains, from which source 

 we might expect a greater depth of ice to move southward and 



