VII. 

 PALEONTOLOGY. 



The length of time which has elapsed since the 

 first known life began upon the earth is to be counted 

 by millions of years, but whether we are to regard it 

 as fifty or a hundred million there is no general 

 agreement. As to when life began, or what were its 

 first forms, no one claims to know. 



The Archsean rocks of Canada, which extend from 

 the region of the great lakes to the northeast and the 

 northwest, and which constitute the backbone of the 

 continent, are regarded as the oldest known sediment- 

 ary rocks. Their maximum thickness is estimated at 

 from forty to fifty thousand feet. 



In this metamorphic Archaean rock is found 

 Eozoon canadense, which, if it is a fossil, represents 

 by far the oldest known living being. 



It is thought by some to be a low form of com- 

 pound protozoan, but the latest authorities have de- 

 cided against its organic origin.* 



Lyell, quoting from Sir Wm, Logan, says: "Its 

 antiquity is such that the distance of time which sep- 

 arated it from the upper Cambrian period, or that of 

 the Potsdam sandstone, may be equal to the time 

 which elapsed between the Postdam sandstone 

 and the nummulitic limestones of the Tertiary period. 

 The Laurentian and Huronian rocks united are about 

 50,000 feet in thickness." 



JEozoon is found in the lower Laurentian. 



* Text Book of Geology. Geikie, p. 695. 

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