1862.] BIGSBY CAMBRIAN AND HURONIAN. 45 



Part II. — The Huronian Formation of Canada not Cambrian ; 

 with Remarks on its Regional Affinities. 



I. Introduction. — The Huronian formation, one of the several 

 great discoveries of the Geological Commission of Canada, will pro- 

 bably be found to be an important member of the fixed rocks of the 

 earth ; for on the north side of the Great Lakes of Canada, where it 

 was first detected, it occupies a district 710 miles long, and there 

 is a considerable area of it on the south-east side of Lake Superior. 

 It is largely and variously developed also in Norway, and probably 

 in other parts of Europe. 



This set of rocks is therefore of great importance, geologically as 

 well as economically, and is fully entitled to be called a formation if 

 we adopt Deshayes's definition of the term, that is, " a certain num- 

 ber of beds laid down under the influence of the same phenomena"*. 



The general feeling of geologists f is that the Huronian of Canada 

 is the same as the Cambrian of Western Europe ; but careful exami- 

 nation into all the circumstances seems to provoke more than a doubt 

 as to the correctness of this view. 



No true Cambrian exists in North America according to DanaJ; 

 and, as far as my experience goes, the Huronian constitutes a group 

 of beds which may be said to be its substitute in place, if not in time. 

 It has received a name from Sir W. E. Logan because it has a new 

 and distinct character, and needed a designation ; and by him and 

 Mr. Murray, his able and enterprising coadjutor, it has been minutely 

 described. 



As I have paid three visits to the greater part of this formation, 

 in Canada, I may be permitted to make the following brief comments 

 upon it ; my object being, first, a summary account of its place and 

 relations, with some small additions of my own; secondly, to point 

 out an all but perfect identity in the members of this formation in 

 Europe and America ; and thirdly, to show that it is not Cambrian. 



II. Characters of the Huronian. — a. Geological position. — The 

 Huronian of Canada occupies a stratigraphical horizon not far from 

 that of the Cambrian of "Wales, between the Laurentian gneiss and 

 the Silurian ; but it is older, for the Cambrian is continuous into, 

 and conformable to the base of the Silurian, when the latter is in 

 an undisturbed and normal state, while the Silurian is invariably 

 transgressive as regards the Huronian formation in both hemispheres. 

 I have seen this exemplified in numerous instances in Lake Huron 

 and Lake Superior. That the traces of life are not found in this 

 formation affords but moderate aid in fixing its date, for this happens 



* Deshayes, Bull. Soc. Geol. de France, N. S., vol. ii. p. 89. 



f Sir W. E. Logan, American Journ. Science, N. S., vol. xiv. p. 227. Sir R. 

 I. Murchison, Siluria, 2nd edit. p. 19. Coquand, Traite des Roches, p. 299. 

 D'Archiac (as I understand), Bull. Soc. Geol. de France, N. S., vol. xviii. p. G64. 

 Morris, Geologist, vol. i. p. 139. 



| Dana (Address, Rhode Island), Canad. Journ. 1855, p. 380. 



§ At the Twin Falls, River Menomonee, south side of Lake Superior ; see 

 Foster and Whitney, Geol. of Land District, p. 24. Also between the Rivers 

 Missassaga and St. Mary, Lake Huron ; see Sir W. E. Logan, Geol. of Canada. 

 1802, p. 5o. 



