1916] 



Lawson: Correlation of P 're-Cambrian Rocks 



17 



oughly established by the rules of priority and respect for the pioneer 

 workers in this field. From the point of view of stratigraphy Huron- 

 ian is the name of a system and embraces the Bruce Series of Lake 

 Huron and its equivalents as well as the Temiskamian and its equiva- 

 lents. By adopting these two terms, the first proposed by Collins 21 in 

 1914 on behalf of the Geological Survey of Canada and the second by 

 Miller 22 in 1911, we avoid the confusion which attaches to the terms 

 Upper and Lower Huronian. Coleman 23 has sought to substitute Sud- 

 burian for Temiskamian but the latter term has priority and should 

 be retained. 



For the third of the grand divisions of pre-Cambrian time repre- 

 sented by epigene rocks I propose, as I have done in previous papers, 

 the retention of the term Algonkian. A name is needed and I know 

 of no better use to which the term Algonkian can be put. The name 

 is, I am well aware, in bad repute and nearly meaningless, but I hope 

 it may be retained to serve the purpose for which it was originally 

 intended, namely, to designate the pre-Cambrian rocks laid down in 

 post-Archean time, and as a name for the corresponding period. Thus 

 defined, Algonkian is a system embracing the Animikian and the 

 Keweenawan. This system might with propriety be included in the 

 Paleozoic, to the great simplification of our general scheme of classi- 

 fication. 



The Ontarian period is separated from the Huronian by a long 

 lapse of time in which no epigene rocks were formed in the region 

 considered, nor anywhere else that we have cognizance of. Geological 

 processes not less important and even more interesting than sedimenta- 

 tion were, however, in operation ; and the record of events and of the 

 passage of time is just as clearly marked as it is in other periods by 

 the accumulation of strata. These events, from the point of view of 

 their distribution in time, comprise: (1) The development of batho- 

 lithic magmas accompanied by uplift and acute deformation of the 

 crust, and the solidification of these into vast bodies of granite. 

 (2) The prolonged degradation of the region and its reduction to a 

 surface of low relief. The rocks formed during the first of these two 

 time-divisions constitute so important an element in the structure of 

 the earth's crust that we can scarcely discuss the problems which they 

 present without the retention of the term Laurentian, which has been 



21 The Huronian Formations of Temiskaming Eegion, Canada, Geol. Survey 

 of Canada, Mus. Bull. no. 8, p. 26. 



Eng. and Min. Journ., Sept. 30, 1911, p. 648. 

 23 Out. Bur. Mines, 23, pi. 1, p. 205, 1914. 



