522 THE AZOIC SYSTEM AND ITS SUBDIVISIONS. 



Barrande, in his earliest communication embodying the results of his 

 life-work among the Palieozoic rocks of Bohemia (1846), did not use the 

 term " primordial," which he later adopted, and in which he included 

 the lowest zone of life ; but he speaks of his division " C " as " forming 

 the base of the Protozoic rocks, according to the latest classification 

 of the Rev. Professor Sedgwick." His (Barrande's) groups " A " and 

 " B " constitute the " Lower Division," comprising all the Azoic forma- 

 tions, subdivided into two gi'oups, their upper one (" B ") being identi- 

 fied by him as the equivalent of Sedgwick's Cambrian, — the confusion 

 in geological nomenclature caused by the introduction of this term hav- 

 ing begun as far back as these earliest days of discussion in regard to 

 the Azoic. and Palaeozoic rocks. 



It appears, however, that Sedgwick, as late as 1854, had not arrived 

 at any definite conclusions in regard to the existence of an Azoic series, 

 for he says of his Cambrian, " that it seems to contain no organic re- 

 mains." But he hastens to add, that the answer to the question when 

 organic life began " is involved in inextricable obscurity." * 



In 1851 1 Messrs. Foster and Whitney made known the existence of 

 a series of rocks on the south shore of Lake Superior, in regard to which 

 they wrote as follows : — 



" Below all the fossiliferous groups of this [the Lake Superior] region, there 

 is a class of rocks, consisting of various crystalline schists, beds of quartz, and" 

 saccharoidal marble, more or less metamorphosed, which we denominate the 

 Azoic System. This term was first applied by Murchison and De Vemeuil to 

 designate those crystalline masses which preceded the Palaeozoic strata. In it 

 they include not only gneiss, but the granitic and plutonic rocks by which it 

 has been invaded. We adopt the term, but limit its signification to those 

 rocks which were detrital in their origin, and which were supposed to have 

 been formed before the da\Yn of organized existence." | 



It is now known that a large part of the vast region adjacent to Lake 

 Superior on the north and east, and included within the limits of Can- 

 ada and British North America in general, is occupied by rocks which 

 by their infra-Silurian position and lithological character belong in the 



"Siluria" (1867), the Azoic is called " Lauren tian, " and is regarded as being "the 

 base of all Palajozoic deposits." 



* British Palseozoic Rocks and Fossils, 1854, Introduction, p. xxxii. 



t A synopsis of their results had in the previous year (1850) been presented to 

 the Department of the Interior, and in this the nature and geological position of the 

 " Azoic System " had been clearly set forth. Senate Documents, 2d Sess. 31st 

 Cong.. 1850-51, II., Doc. 2, pp. 147-152. 



t Foster and Whitney's Report on the Geology of the Lake Superior Land Dis- 

 trict, Vol. II. The Iron Region, together with the General Geology, 1851, p. 3. 



