18 THE CANADIAN NATURALIST. [Yol. ix. 



No. 3 includes : 



a. Utica slates. 



h. Hudson Kiver or Lorraine Shales. 



c. Trenton limestone. 



d. Bird's-eye and Black River limestone. 



e. The Quebec group and its equivalents, Chazy 



and Calciferous. 

 /. Potsdam. 



Subdivision e. the Quebec group, is the one about which so 

 much discussion has arisen and so many different opinions have 

 been expressed. Indeed so varied have these been that it is now 

 almost impossible to suggest anything which some one has not 

 already suggested, but most of these opinions have been advanced 

 on palseontological, mineralogical or theoretical grounds, without 

 any study of the actual stratigraphy in the field. According to 

 the latest determination, by the geological corps, under my pre- 

 decessor Sir W. E. Logan, the Quebec group is divided into 

 three conformable formations, viz. in decending order : — 



The Sillery. 

 The Lauzou. 

 The Ldvis. 



These have been supposed to occupy the whole of the region 

 lying south of the St. Lawrence between the great St. Lawrence 

 and Champlain fault and the Upper Silurian overlap, notwith- 

 standing the very diverse mineralogical, palaeontological, and 

 physical conditions under which they appear in different parts 

 of the area. The base and the summit of the middle division, 

 which was only introduced in 1866, has been supposed to be 

 characterised by copper ores, dolomites and serpentines, and it 

 would really seem that in mapping the structure the presence of 

 any one of these has almost invariably been made to determine 

 the limits of this division. It is not, however, my object now to 

 refer to the past, or to recapitulate the opinions of others, and I 

 shall confine myself as much as possible to a statement of my 

 own views respecting the stratigraphy of the Quebec group. 



First, then, I may say that I recognize in it three distinct 

 groups, which in descending order may be enumerated as 



1. The Lower Silurian group, Levis formation. 



2. The Volcanic group, probably Cambrian. 



3. The Crystalline Schist group. 



