100 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Feb. 23, 



stone near the bottom, with nodules of both pale and dark limestones. 

 The dark fragments are identical with the limestone of Jeune Lorette, 

 not only mineralogically, but as containing the same Trilobites, Corals, 

 Encrinital stems, and Micrchisonics. Mr. Logan states similar facts, 

 but does not point out the localities. 



The fissures of the clay-shale of this second road are often coated 

 with copper-pyrites ; and we meet with Graptolites, Fenestella, and 

 Glauconome. 



In the middle and at the foot of this road the strike is N.N.E. 

 and the dip E.S.E. Z85°. 



Calc-spar veins are common in the conglomerates here, and inter- 

 sect the nodules and matrix indifferently. 



The strata along shore from here either westward to the mouth of 

 the River Chaudiere, or eastwards toward Beaumont, as far as they 

 can be readily made out, are in kind and in mutual relation the same 

 as those on the north shore of the St. Lawrence and about Point 

 Levi ; but the ground is unfavourable for minute examinations. 



Ridges of clay-slate, principally red, but often green and black, 

 with layers of greywacke, form the barrier of the Chaudiere Falls. 



A third of a mile east of the Lauzon Ferry there is a horizontal 

 section of a set of contortions, the external layers of which gradually 

 return to the normal direction in the manner represented in PL 38. 

 fig. 5 of Sir H. De la Beche's " Geological Sections." 



General observations. — The gneiss of the north shore of the St. 

 Lawrence in this vicinity is of the kind prevalent in the Canadas, 

 and is conformable to it. The group of round-topped hills and 

 mountains, about twenty miles across, of which gneiss forms the 

 greater part, trends N.E. and S.W., with valleys interposed of various 

 sedimentary rocks, among which we find Trenton limestone. 



[We find Potsdam sandstone to be extremely thin here, as has 

 been verbally remarked by Sir R. Murchison. Its thickness in- 

 creases as we travel westward, until in Lake Superior and in the 

 Mississippi valley it is in great mass. — April 20.] 



The Potsdam sandstone and Trenton limestone here rest uncon- 

 formably upon the subjacent crystalline rocks, and are, therefore, 

 posterior to them. The same takes place on the Great Lakes, at 

 Montreal, Cape Tourment, Lower Canada, &c. 



The fossil remains in the Trenton limestone occur only in patches, 

 and the different localities, as Lorette, Beauport, &c., each have some 

 exclusively. The Asaphiis gig as and Rhynchonella herd together in 

 particular beds. 



Utica slate occurs in very limited quantity about Quebec ; a nar- 

 row band only is visible, characterized by its uniform shaly aspect, 

 and by the presence of Triarthrus Beckii and Graptolites. In 

 fact, here as elsewhere, it speedily merges into the Hudson River 

 Group. 



The Hudson River Group is enormously developed in this part of 

 North America. The tract occupied by it is at least 500 miles long, 

 from Lake Temiscouta on the N.E., to the State of New York near 

 Lake Ontario on the S.W. ; and it extends from thence in great de- 



