DISCUSSION. 



Dr. Alfred R. C. Selwyn :* Sir William Logan alone assigned the rocks 

 of the city of Quebec to the Levis division of his Quebec group ;t Selwyn 

 alone assigned the rocks of the city of Quebec to the Hudson-Utica horizon , 

 or above the Trenton, and pronounced them, before any fossils had been 

 found in them, to be the same as those on the northern shore of the Island of 

 Orleans, which had been assigned by Logan to Hudson-Utica. Fossils since 

 found in the city of Quebec have proved the correctness, so far, of Selwyn's 

 view. Whether Logan and Selwyn are right in placing these rocks above 

 the Trenton is thus the only question now at issue. 



Do the fossils determined by Mr. Ami conclusively prove his contention, 

 that they are not above but below? In this connection, see "Geology of 

 Canada," 1863, pages 199 to 204, for list of fossils and description. 



Mr. C. D. Walcott : Sir William Logan, in his original definition of the 

 Quebec group, divided it into two parts in the vicinity of Quebec. The 

 Point Levis series consists of the graptolite-bearing shales of Point Levis, 

 with their enclosed conglomerates, in which upper Cambrian or Potsdam 

 fossils were found, as he supposed, in association with fossils of the age of 

 the Calciferous formation of New York. Although no fossils were found in 

 the rocks of Quebec city proper they were correlated with the Levis series. 

 Mr. Ami has now found a fauna in the Quebec city rocks which is distinct 

 from that of Point Levis, and I think that there should be two names, one 

 for the rocks of Calciferous age at Point Levis, and another for the Quebec 

 rocks. I think the name Quebec should be restricted to the Quebec city 

 rocks, which carry a distinct fauna from the strata at Point Levis, and that 

 the name Levis should be applied to the graptolitic shales and the lime- 

 stones in which the Calciferous fauna occurs. If Mr. Ami's determination 

 of the fauna is correct, the horizon of the Quebec city rocks is that of the 

 Trenton, probably the lower Trenton, and perhaps the upper portion of the 

 Chazy of the New York section. As the rocks at Quebec are of a peculiar 

 physical development and contain a peculiar fauna, I would suggest, if ac- 

 ceptable to the Canadian geologists, that the name Quebec be restricted to 

 that series of rocks, and that the Point Levis rocks be arranged under the 

 name Levis. 



For the series of strata that have been formerly included under Quebec 

 as about the Calciferous-Chazy horizon, as originally defined by Logan, 

 which includes the Point Levis series, the Quebec city series, the Phillipsburg 



*In a note communicated to the Society, 

 t" Geology of Canada," 1803, p. 201. 



LX XIII— Bull. Geol. Soc. Am., Vol. 2, 1890. (i^Ol) 



