walcott.] CANADIAN EXTENSION. 119 



entire section 2,000 feet. A number of species of the Olenellus fauna 

 were found in the pebbles of the conglomerate near St. Denis Station 

 on the Grand Trunk Railway, and also at Bic Harbor. 1 



The reference by Mr. Richardson of the rocks mentioned in the pre- 

 ceding paragraph to the Potsdam zone is objected to by Dr. A. R. 0. 

 Selwyn. 2 He says that after examining a considerable portion of these 

 supposed Potsdam rocks, there is in his opinion at present no sufficient 

 evidence, either paleontological, stratigraphical, or raineralogical, for 

 separating this belt from other very large areas of the Quebec group, 

 hitherto assigned, the larger part to the Lauzon, but in some places 

 also to the Levis and Sillery formations. He states that on any map 

 now published it is best to include the whole of the rocks of this great 

 fossiliferous belt in one group, as the data are insufficient to separate the 

 Potsdam zone from the other rocks of the Silurian. The group referred 

 to is No. I, 3 the Lower Silurian. The second is " the volcanic group, 

 probably Lower Cambrian." Group No. 2 is described as consisting of 

 a great variety of crystalline, subcrystalline, and altered rocks, includ- 

 ing red, gray, and greenish siliceous slates and argillites, great masses 

 of diorite, epidotic and serpeutinous breccias and agglomerates, etc. 4 

 Of the age of this group he says : 



If fossils are found I should expect them to indicate a lower horizon than the Levis 

 formation, probably not far removed from that of the St. John group and Atlantic 

 coast series of Nova Scotia, or Lower Cambrian. 6 



This series forms part of the Sillery formation of Mr. Logan. 



In speaking of the reference of the Volcanic group to the Cambrian 

 Dr. Selwyn quotes from the paper read before the Royal Society of 

 Canada in May, 1882, «s follows : 6 



The upper portion of this series was designated " the volcanic belt " from the asso- 

 ciation with it, especially on the southeast side of the main axis, of a great variety 

 of what were considered to be altered eruptive and irruptive rocks, but whether 

 the strata forming this igueous belt are more nearly allied to the Lower Cambrian 

 than to the Upper Huronian is not, fossils being absent, easily determined. 



On the map of the Dominion of Canada geologically colored from 

 surveys made by the Geological Corps from 1842 to 1882, under the 

 direction of Dr. Selwyn, there is quite a broad belt of rocks colored 

 Cambrian that extends from Cape Rosier on the Gaspe Peninsula 

 southeasterly along the shores of the St. Lawrence to Point Levis, Que- 

 bec. From Point Levis it turns more to the south, extending along the 

 western margin of the Archean anticlinal to Mississquoi Bay,, at the 

 foot of LakeChamplain. A narrower strip is represented as extending 



1 Op. cit., p. 130. 



2 Report of observations on the stratigraphy of the Quebec group and the older crystalline rocks of 

 Canada. Geol. Survey Canada, report of progress, 1877-78, 1879, p. 4A. Can. Nat., new ser., vol. 9, 

 1879, pp. 17-31. 



■Op. cit., p. 3 A. 4 0p.cit.,p.5A. « Op. cit., p. 6 A. 



•Notes on the geology of the southeastern portion of the Province of Quebec. Geol. Survey 

 Canada, report of progress, 1880-'81-'82, 1883, p. 2A. 



