368 THE GREAT ICE AGE 



absence on the hillsides, and with the prevalent direction of 

 striation and boulder drift from the north-east.^ 



All these indications coincide with the conditions of the 

 modern boulder drift on the lower St. Lawrence and in the 

 Arctic regions, where the great belts and ridges of boulders^ 

 accumulated by the coast ice would, if the coast were sinking, 

 climb upward and be filled in with mud, forming a continuous 

 sheet of boulder deposit similar to that which has accumulated 

 and is accumulating on the shores of Smith's Sound and else- 

 w^here in the Arctic, and which, like the older boulder clay, is 

 known to contain both marine shells and driftwood.^ 



<rhe conditions of the deposit of "till" diminished in intensity 

 as the subsidence continued. The gathering ground of local 

 glaciers was lessened, the ice was no longer limited to narrow 

 sounds, but had a wider scope, as well as a freer drift to the 

 southward, and the climate seems to have been improved. 

 The clays deposited had few boulders and many marine shells, 

 and to the west and north there were land-producing plants 

 akin to those of the temperate regions; and in places only 

 slightly elevated above the water, peaty deposits accumulated. 

 The shells of the Leda clay indicate depths of less than loo 

 fathoms. The numerous Foraminifera, so far as have been 

 observed, belong to this range, and I have never seen in this 

 clay the assemblage of foraminiferal forms now dredged from 

 200 to 300 fathoms in the Gulf of St. Lawrence. 



I infer that the subsidence of the Leda clay period and of 

 the interglacial beds of Ontario belongs to the time of the sea 

 beaches from 450 to 600 feet in height, which are so marked 

 and extensive as to indicate a period of repose. In this period 



^ Notes on the Post-Pliocene Canadian Naturalist^ op. cit. ; also 

 Paper by the author on Boulder Drift at Metis, Canadian Record of 

 Science^ vol. ii., 1886, p. 36, et seq. 



2 For references see '* Royal Society's .Arctic Manual," London, 1875, 

 op. cit. 



