No. 2.] MACFARLANE — CANADIAN STRATIGRAPHY. 93 



take notice when discussing the theory which Mr. Selwyn builds 

 upon it. 



III. Mr. Selwyn states that, on the River Etchemin, the rocks 

 of his second division crop out apparently unconformably from 

 beneath the fossiliferous belt or Levis formation. But he is 

 uncertain whether this " apparent unconformity" may not be a 

 fault, and therefore it would seem hazardous to base much 

 theorizing upon it. I cannot detect, elsewhere in Mr. Selwyn's 

 paper, any unequivocal example of discordance such as would 

 prove that the Levis formation is quite distinct from the under- 

 lying "Volcanic Group." 



IV. Mr. Selwyn notes the occurrence in his second division 

 of " altered volcanic products," both intrusive and inter-stratified, 

 and speaks of a great development of those Volcanic rocks. The 

 term "volcanic" is very seldom used by modern lithologists as 

 indictaing a particular texture or composition in a rock. Among 

 older authors, Sartorius von Waltershausen writes of the volcanic 

 rOcks of Sicily and Iceland, all of which occur in the neighbour- 

 hood of active volcanoes. Von Richthofen, in his Natural System 

 of volcanic rocks, writcen in 1868, refers exclusively to tertiary 

 and post-tertiary eruptive rocks ranging from rhyolite to basalt. 

 Mr. Selwyn in applying the term to intrusive rocks of Cambrian 

 or Silurian age probably uses it in the sense of eruptive, for it 

 would be very difficult to shew any connection between them and 

 volcanic vents. In this case he does not put on record a new 

 fact, but merely an old opinion expressed by previous observers. 

 But Mr. Selwyn claims further in reference to these rocks " that 

 " neither their true stratigraphical position nor their geological 

 " characters have been correctly defined, and they have, regardless 

 " of these, been confounded and incorporated with the true Sillery 

 " sandstones, which are only a local development of thick sand- 

 " stones at several horizons in the Quebec group or fossiliferous 

 " Ldvis formation." The geological characters mentioned have 

 probably reference to their lithological features, and we are left to 

 infer that certain eruptive crystalline or sub-crystalline rocks have 

 been described as sandstones by 3Ir. Selwyn's predecessors, and 

 that he has been the first to determine them correctly. But when 

 Sir William and his assistants classed a certain diorite, for 

 instance, in the Sillery formation they did not therefore deter- 

 mine it as a sandstone. When I speak of the Primitive Gneiss 

 formation I do not necessarily mean that every rock in it is a 



