106 E. W. ELLS ON THE GEOLOGY OP 



wide area. Aud it is with the hope that some of the puzzling questions in connection 

 with the peculiar series of rocks known as the "Quebec group" may be simplified, that the 

 evidence to hand and the conclusions as to its structure now arrived at are here put forth, 

 for there is no doubt that the conflict of opinion which has prevailed concerning this 

 group of strata, and the ajiparent mistiness which has attended their study during the past 

 twenty years has had the effect of discouraging investigation in this direction, except in 

 the case of those persons directly interested in the subject. 



Prior to 1860, it was held by Canadian geologists that the greater part of the rock 

 formations east of the St. Lawrence aud extending to the boundaries of Maine, New Tlamp- 

 shire aud Vermont, were of the age of what was then regarded as the Hudson liiver divi- 

 sion of the New York geologists, with the exception of certain areas towards the eastern 

 border, which were regarded as upper Silurian or Devonian, and certain other x)ortions in 

 the vicinity of, and to the south of, Montreal which were assigned to their proper places 

 in the geological scale as the equivalents of the Potsdam, Calciferous, Chazy and Trenton. 



The rocks of this great area east of the St. Lawrence, presenting a breadth of more 

 than 120 miles east of Montreal and a length from the Vermont boundary to the extremity 

 of Gaspé peninsula of about 4*75 miles, exhibit a very great diversity of character. Thus, 

 a large portion are fossiliferous, while other great areas are highly crystalline aud show 

 no traces of the remains of organic life. Other great areas of slates and hard sandstones 

 have also not yet disclosed any fossil evidence by which their age can be fixed, but are 

 clearly a distinct series of rocks from the fossiliferous sediments on the one hand and the 

 crystalline schists on the other. In structure and general arrangement, it may be said 

 these latter constitute a series of anticlinal ridges, generally prominent and easily recog- 

 nized, which extend parallel to the course of the St. Lawrence at a considerable distance 

 inland. 



The structure of the several formations here found is complicated by the presence of 

 numerous great faults, and by a wonderful series of crumplings, foldings and frequent 

 overturns, which have so changed the natural order of deposition as to present one of the 

 most complicated pieces of geological arrangement to be found anywhere on this 

 continent. Thus, in places, fossiliferous beds of the Trenton or Hudson River formations 

 are found in contact with, and in apparently conformable sequence beneath, recognized 

 strata of Cambrian age ; while, in other places, the Silurian and Devonian sediments are 

 so intimately infolded with Cambrian and Cambro-Silurian rocks as for many years to 

 cause them to be regarded as integral portions of the same formation. 



The Hudson River or Utica age of the rocks in the vicinity of the St. Lawrence, south 

 of Quebec, both on the north and south side of the river, was one of the first points 

 accurately determined in the geological structure of the province of Quebec' These 

 contain an abundance of characteristic fossils in an excellent state of preservation, and 

 present no difficulty from the paleontological standpoint. Where these Hudson River rocks 

 cross the St. Lawrence from north to south, about ten miles south of the city of Quebec 

 they dip directly beneath a great series of red, green and black shales, with hard sand- 

 stones, which can thence be crossed for many miles in a south-east direction and which 

 would therefore appear to form an upper portion of the Hudson River series, and this 

 was the view maintained by geologists generally for some years. The fact that 



' Rep. Geol. Survey, Logan, 1847-48. 



