247 



which are added all the unstratified crystalline rocks forming the centre 

 of the Laurentine Mountains, such as granite, syenite, diorite and 

 porphyry, mixing together strata and eruptive rocks, an attempt which 

 was unexpected from a stratigraphical geologist. His Huronian 

 system is formed of a mixture of the St. Albans group of the Upper 

 Taconic, with the Triassic rocks of Lake Superior, the trap native- 

 copper bearing rocks of Point Keeweenaw, and the dioritic dyke con- 

 taining the copper pyrites of Bruce mine on Lake Huron. 



The different dislocations which have affected the rocks of the 

 vicinity of Quebec have not brought to light the complete series of 

 the Taconic nor of the LoAver Silurian, and the difference of opinion 

 that exists between Mr. Logan and myself is partly owing to this 

 want. In his Remarks on the Fauna of the Quebec Group of Rocks and 

 the Primordial Zone of Canada^ Jan., 1861, and in his Considerations 

 relating to the Quebec Group^ May, 1861, Mr. Logan gives the following 

 series for the vicinity of Quebec : — 



u". — Dark gray shales and sandstones ("Hudson Eiver). 



u^ — Black shales (Utica). 



b. — Limestone (Birdseye, Black River, and Trenton). 



q^. — Sandstone and red shales (Sillery). 



q^. — Red and green shales. 



q*. — Green and gray shales and sandstones. 



q^. — Sandstones and magnesian conglomerates. 



q^. — Green shales. 



q^. — Magnesian conglomerates and shales. 



p^- Sandstones. Uotsdam. 



p\ — Black shales and limestones. ) 

 g. — Gneiss (Laurentian). 



All the fossils found at Point Levi are placed by Mr. Logan in a 

 single group of strata, which he calls the Quebec group. He speaks also 

 several times of shales and limestones beneath the Quebec group, 

 which he considers as deep-water deposits of the Potsdam Sandstone. 

 Unhappily he does not give any precise localities or section at Quebec 

 or Point Levi where that Potsdam may be found, and I was unable 

 to discover what strata he thus names. But wherever these strata 

 may be located, he says that he found no fossils in them in Canada, 

 " but that the shales resemble those in which Oleni have been found in 

 Georgia." So that Mr. Logan considers the Georgia Slates and the 

 Potsdam Sandstone as the same group, one being a deep-water deposit 

 and the other a coast deposit. I will only remark that at Mr. Parker's 

 house, in Georgia, the two groups are found one above the other. 



Mr. James Hall, in his last descriptions of the Georgia Trilobites 

 (Thirteenth Annual Report of the State Cabinet of Natural History 



Quebec Group. 



