Geographical and Climatal Conditions. 



With reference to these I shall first refer to the district from the Atlantic 

 to the head of Lake ( Ontario. 



In this district and the eastern part of North America generally, it is, I 

 think, universally admitted that the later Pliocene period was one of conti- 

 nental elevation, and probably of temperate climate. The evidence of this 

 ia too well known to require re-statement here. It is also evident, from the 

 raised beaches holding marine shells, extending to elevations of 600 feet, 

 and from bowlder drift reaching to a far greater height, that extensive Bub- 

 mergence occurred in the middle and later Pleistocene. This was the age of 

 the marine Leda clays and Snxirum sands found at heights of 600 feet above 

 the sea in the St. Lawrence valley nearly as far west as Lake Ontario. 



It is reasonable to conclude that the till or bowlder clay under the Leda 

 clay belongs to the intervening period of probably gradual subsidence, ac- 

 companied with a severe climate and with snow and glaciers on all the higher 

 grounds, Bending glaciated stones into the sea. This deduction agrees with 

 the marine shells, bryozoa, and cirripedes found in the bowlder deposits on 

 the lower St. Lawrence, with the unoxidized character of the mass, which 

 proves Bubaquatic deposition, with the fact that it contains soft bowlders, 

 which would have crumbled if exposed to the air, with its limitation to the 

 lower levels and absence on the hill-sides, and with the prevalent direction 

 ofstriation and bowlder drift from the northea-l 



All these indications coincide with the conditions of the modern bowlder 

 drift on the lower St. Lawrence and in the arctic regions, where the great 

 belt- and ridges of bowlders accumulated by the coast ice would, if the coast 

 were sinking, climb upward and be tilled in with mud, forming a continue 

 sheet of bowlder deposit similar to that which has accumulated and is ac- 

 cumulating on the shores of Smith's sound and elsewhere in the arctic, and 

 which, like the older bowlder clay, is known to contain both marine shells 

 ami drift-wood.'j' 



The condition- of tin deposil of till diminished in intensity as the Bubsi- 

 dence continued. The gathering ground of local glaciers was lessened, the 



ice was no longer limited to narrow sounds, hut had a wider scope as well 



:,- :i tVe. r drift to the BOUthward, :i 1 1< I the climate seems to have been im- 

 proved. The clays deposited had few bowlders and many marine shells, 

 and to the west and north there were deposits of land plants, and on land 

 elevated above the water peaty deposits accumulated. 



The shells of the Leda clay indicate depths of less than Inn fathoms. The 

 numerous foraminifera, so far as have 1m en observed, belong to this range, 



• ei ii' in Natural lot, op oit. ; also paper by the author on Bowlder 



I > r i > < <it Metis, Canadian R< I ■•' 8< ience, Vol. II, i 



ee Royal 3 kretic Manual, London, 1876, op. clt. 



