196 Tertiary Fossils of Canada, ^c. 



or been removed by denuding agencies. The question awaits 

 further explorations for a satisfactory answer. 



In the mean time it is certain that the boulder clay and 

 deposits corresponding in arrangement and mechanical character 

 to the Leda clay and Saxicava sand of the Lower St. Lawrence 

 exist in these more western regions, though they have not been 

 found to contain marine fossils. 



4. CLIMATE OF CANADA IN THE PLEISTOCENE PERIOD. 



The climate of this period and the causes of its difference from 

 that which now obtains in the northern hemisphere, have been 

 fertile subjects of discussions and controversies, which I have no 

 wish here to re-open. I merely propose to state in a manner 

 level to the comprehension of the ordinary reader, the facts of 

 the case in so far as relates to Canada, and an important infe- 

 ence to which they appear to me to lead, and which if sustained 

 vvill very much simplify our views of this question. 



Every one knows that the means and extremes of annual tem- 

 perature differ much on the opposite sides of the Atlantic. The 

 isothermal line of 40° for example passes from the south side of 

 the gulf of St. Lawrence, skirts Iceland and reaches Europe near 

 Drontheim in Norway. This fact, apparent as the result of obser- 

 vations on the temperature of the land, is equally evidenced by 

 the inhabitants and physical phenomena of the sea. A large pro- 

 portion of the shell fish inhabiting the gulf of St. Lawrence and the 

 coast thence to Cape Cod, occur on both sides of the Atlantic, 

 but not in the same latitudes. The marine fauna of Cape Cod 

 is parallel in its prevalence of boreal forms with that of the south 

 of Norway. In like manner the descent of icebergs from the 

 north, the freezing of bays and estuaries, the drifting and pushing 

 of stones and boulders by ice, are witnessed on the American coast 

 in a manner not parallelled in corresponding latitudes in Europe. It 

 follows from this that a collection of shells from any given latitude 

 on the coasts of Europe or America, would bear testimony to the 

 existing difference of climate. The geologist appeals to the same 

 kind of evidence with reference to the climate of the later tertiary 

 period, and let us enquire what is its testimony. 



The first and most general answer usually given, is that the 

 pleistocene climate was colder than the modern. The proof of 

 this in Western Europe is very strong. The marine fossils of this 



