THE SUCCESSION OF DEPOSITS. 37 



(b) Mid-Pleistocene : Submergence of coasts and re- 



elevation of interior plateaus with milder 

 climate. — Inter-glacial period. 



(c) Later Pleistocene : Submergence of plains, and 



general ice drift, with local glaciers in 

 mountains. 



Early Modern or Post-Glacial. — Second continental 

 period, in which the land regains almost all the 

 extension of the Pliocene time. Age of the Mammoth 

 and Mastodon and of Paheocosmic man. — Post-glacial 

 Fauna. 



Modern or Recent. — Submergence of sliort duration, 

 terminating the age of Pahieocosmic man. Re-eleva- 

 tion of continents to present le\els. Modern races 

 of men and Modern Fauna. 



Let us now consider the several members of the Pleis- 

 tocene more in detail, especially in those regions in which 

 they have been studied by the author. 



GENERAL DESCRIPTION OF PLEISTOCENE DEPOSITS. 



1. — The Loioer Boulder-Clay. 



Throughout a great part of Canada there is over all 

 tlie lower levels a true "Till," consisting of hard gray 

 clay, filled with stones and thickly packed with boulders. 

 In many places, however, the clay becomes sandy, and in 

 some portions of the upper carboniferous and triassic 

 areas, the paste is an incoherent sand. The mass is usually 

 destitute of any stratification or subordinate lamination ; 

 but sometimes in thick beds horizontal lines of different 

 texture or colour can be perceived, and occasionally the 

 clay intervening between the stones becomes laminated, 

 or at least shows such a structure when disintegrated by 



