CHAPTER II. 



ARCH^AN SYSTEM AND ARCHEOZOIC ERA. 



THE events recorded in this oldest system of rocks, in 

 this first volume of the book of time, are so few and so 

 imperfectly recorded that their chief interest consists in 

 the fact that they are the first. There is a fascination 

 about the beginning the mythical period of all history. 

 The distinctness of this system was for a long time un- 

 recognized. It has now, chiefly by the labors of Ameri- 

 can geologists, been completely established. In no single 

 instance have these rocks been found to graduate into the 

 Paleozoic. There is absolutely everywhere an uncon- 

 formity between them and every other system. No such 

 complete and universal break occurs anywhere else in the 

 rocky series as occurs here (Fig. 165). It is, therefore, 



1 2 



FIG. 165. Section showing Primordial unconformable on the Archaean : 1, Archaean 

 or Laurentian ; 2, Primordial or lowest Silurian. (After Logan.) 



properly called a distinct system and a distinct era 

 more distinct, in fact, than any other. 



Here, then, we have the oldest known rocks. Are they, 

 then, absolutely the oldest the primitive rocks, as some 

 imagine ? By no means. They are stratified rocks, and 

 therefore consolidated sediments, and therefore, also, the 



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