412 Newer Pliocene and Post Pliocene Deposits 



I know little of the fauna of this older sea area. The locality 

 above referred to aflfords only Saxicava rugosa, Mya (fragments), 

 Mytilus edulis, Tellina Groenlandica ; and we do not certainly 

 know that even the Leda inhabited the deep sea bottom 

 aroilnd Montreal at this time, since the lower part of the Leda 

 clay appears destitute of fossils. It was then over 60 fathoms un- 

 der water, and probably not tenanted by many animals. The 

 waters of this sea must have been traversed by the arctic currents, 

 ice laden in the spring, and its northern shores probably had a 

 climate of as low mean temperature as that of Labrador, though 

 perhaps less extreme. 



At a still earlier period than that indicated by the beaches last 

 described, the waters had been far higher ; for large boulders of 

 laurentian rocks are found on tlie summit of the mountain, and 

 much higher than this on the sides of the mountains of the 

 Eastern Townships and of New England. The limited seas there- 

 fore in which the marine fossils above named lived, were preceded 

 by a state of things in which an extensive oceanic surface was 

 spread over North America, and probably only a few isolated 

 peaks and ridges prcgected above the waters. Of the shores of 

 this ocean and the animals that may have lived near them, I know 

 nothing ; and the sea deposit corresponding to this period is the 

 lower part of the Leda clay and the surface of the great bed of 

 boulder clay below it, neither of which have afforded fossils. 



I have not as yet referred to this lower member of the forma-, 

 tion, and I have nothing new to offer in relation to it. All my 

 observations, whether in Nova~ Scotia or Canada, incline me to 

 adhere to the view long advocaied by Sir C. Lyell, and recently 

 very ably illustrated by Professor Hitchcock,* that the true 

 boulder clay has resulted from the gradual subsidence of the 

 land under the influence of a cold climate, producing a deposit 

 along the shores, resulting from the joint action of ice and water ; 

 and this, as the land sunk, spreading itself over the whole surface- 

 As an additional fact confirmatory of this view, I may mention 

 the appearance of successive ridges presented by the surface of the 

 drift, and the linear distribution of stones in it, where it ap- 

 proaches elevated land. These appearances are often observable 

 in cuts made in the drift in the vicinity of Montreal. This ex- 

 planation of course implies that the land whose elevation we have 



* Smithsonian Publications, 1856. 



