﻿490 Ccmadian Record of Science. 



These views were first published in the Canadian 

 Naturalist for December, 1860, and in the American 

 Journal of Science for March, 1861, where the opinion 

 was expressed that " this series of rocks, to which the 

 term ' Quebec Group ' was now first applied, represents a 

 great development of strata about the horizon of the 

 Chazy and Calciferous, brought to the surface by an 

 overturn anticlinal fold, with a crack and dislocation 

 running along the summit, by which the Quebec Group 

 was brought to overlap the Hudson River formation." 



In this connection it may oe mentioned that the new 

 views thus expressed by the Canadian Survey were con- 

 firmatory of those advanced by Emmons years before, who 

 had maintained that the strata of the group were beneath 

 the Birds-eye limestone. 



The discovery of these fossils and their satisfactory 

 determination as Calciferous by Billings, led naturally to 

 renewed explorations among the rocks of this area. The 

 presence of several great faults was recognized and their 

 relations to the various groups were determined. The 

 series of slates and sandstones, limestones and conglom- 

 erates of the Quebec and Levis area was divided into two 

 principal groups, of which the supposed lower portion 

 included the limestone, greyish slates and conglomerates, 

 which was styled the Levis division, while the great bulk 

 of the red and green slates with the sandstone was placed 

 at the top of the series and styled Sillery. These were all 

 held to be newer than the Potsdam formation. 



Exception was taken to these views of Logan by Prof. 

 Jules Marcou, who, after an examination of the rocks in 

 this locality, as well as of certain strata in the vicinity of 

 Phillipsburgh, which were also regarded by Billings as 

 about the same horizon, came to the conclusion that the 

 strata of the ' Quebec Group' of Logan were of the age of 

 the middle portion of the Taconic and far below the 

 Potsdam sandstone. 



