24 PARALLELISM OP THE QUEBEC GROUP. 



least 6000. In Pennsylvania, Prof. Rogers says, his Auroral series, 

 — supposed by him (and correctly too I believe) to represent the 

 calciferous Chazy and Black River, — is from 2500 to 5500 feet 

 thick. It is thus very clear that, either the same strata must be 

 greatly thicker in the south-eastern region than they are in the 

 north-western, or else that the whole formation is swollen by ad- 

 ditional deposits. Perhaps both of these reasons should be taken 

 into account. 



In 1859 I made an examination of all the Calciferous and 

 Chazy fossils, in the Provincial Museum, and found that there were 

 41 species in the former and 129 in the latter, but not one species 

 was clearly identified as common to the two formations. I believe 

 that between the Calciferous and Chazy, as developed west of the 

 line, in Canada, there is an almost total break in the succession of 

 life. There are few geologists who believe in periodic extinctions 

 of all animal life extending over the whole earth. It is almost 

 certain, that gaps of this kind are mere local phenomena. 



And if so,then somewhere else strata will sooner or later be found, 

 holding a fauna composed partly of species occurring in the beds 

 below and partly of those found in beds above the gap, thus 

 connecting the two formations. I think it probable that a large 

 portion of the Quebec group is of an age between the Calciferous 

 and Chazy. But I do not believe that this would be sufficient to 

 account for so great a number of species distinct from those of 

 these two formations. The existence of zoological provinces in 

 the Silurian seas, although not yet clearly proved, is something that 

 should always be kept in mind, while endeavouring to work out 

 a problem such as that presented by the fauna of the Quebec 

 group. 



Of the 129 species of the Chazy limestone, twenty-one pass up- 

 wards into the overlying formations. In the Black River limestone, 

 lying just on the top of the Chazy, we find a sudden and great in- 

 crease in the number of species. Nearly all of these pass upwards 

 into the Trenton and many of them into the Hudson River. 

 There is here another break (between the Chazy and Black River) 

 but not so decided as that between the Calciferous and Chazy. 

 When we find (as in the instance of the Black River and Trenton 

 Fauna) a sudden appearance of a vast number ot new species, 

 we must suppose either that all these new species were suddenly 

 created at the time the beds, in which we first find them, were 

 deposited ; or, that previous to the deposition of these beds, they 



