Sir W, E. Logan on the Quebec Groupj ^c, 201 



themus (Green), Trinucleus concentricus, Asaphus platycephalus 

 (Stokes) ; those contained in the black shales are GraptoUthus 

 hicornis (Hall), G. pristis (Hessinger). There is thus no doubt 

 whatever that the limestones are of the Trenton and the shales of 

 the Utica formation. 



On the opposite side of the north channel at the upper end of 

 the Island of Orleans there occur about 500 feet of black bitumi- 

 nous shale inters tratified "with occasional beds of gray yellowish- 

 weathering calcareous sandstone, and arenaceous limestone ; they 

 in some parts hold GraptoUthus hicornis and G. pristis, and there 

 is little doubt are subordinate to the Utica or Hudson River forma- 

 tion. They dip S. W. <^ 50®, and there rests upon them (the 

 contact being visible) a series of magnesian shales and conglome- 

 rates dipping in the same direction and at the same angle. These 

 magnesian strata are of the same character as those at Point 

 Levis, and belong to the Quebec group. They thus overlap the 

 black shales which are probably overturned as represented in 

 the diagram (fig. 1). 



Fig. 2. 



Campmentd'our3 Chahnel Sr Joseph 



a, Birdseye and Black River limestone. 



6, Ste. Marie sandstone. 



c, Huronian slate conglomerate and jaspar conglomerate. 



H, Level of Lake Huron. 



Sy Level of the Sea. 



Horizontal and vertical scale, 1 inch to 1 mile. 



In his explorations of last year on Lakes Superior and Huron 

 Mr. Murray ascertained that the lowest rock in that neighbour- 

 hood well characterised by its fossils belongs to the Birdseye and 

 Black River group, and that it rests conformably upon the sand- 

 stones of Sault Ste. Marie. These sandstones and their equivalents, 

 consisting of red and yellowish- white beds, are traceable on the 

 south side of Lake Superior from Marquette to the River St. Marie 

 and compose Sugar Island and probably the north part of Neebish 

 Island ; they extend to the north part of St. Joseph Island, and are 

 met with on the Island of Campment d'Ours. In one of the white 

 beds near Marquette, Mr. Murray obtained a Pleurotomaria resem- 

 bling P. Laurentina of the Calciferous formation and observed the 

 occurrence in the same bed of a species of ScoUthus. The mass 



