37S REVIEWS — ESQUISSE GEOLOGIQUE DU CAXADA. 



Esquisse Geologique du Canada. Pour servir a V intelligence de la 

 carte geologique et de la collection dee mineraux envoi/ecs a V Exposi- 

 tion I niverselle de Paris, 1855. Par W. E. Logan et T. Sterry 

 Hunt. Paris, 1855. 



This admirable little brochure, published in Paris during the Expo- 

 sition, was drawn up in French by Mr. Hunt, with the co-operation 

 of Sir William Logan, chiefly to serve as a guide to the geological 

 map and collection of mineral products exhibited in the Canadian 

 department. The beautifully executed map, alluded to in the first 

 number of the new series of our Journal, accompanies the volume. 

 A belter general view of Canadian geology it is impossible to obtain ; 

 and as no other connected view of our geology, beyond a few sketches 

 of very limited extent, has yet been given to the public, we are glad 

 to learn that its re-issue in an English dress may shortly be antici- 

 pated. Supplying a long-felt want, in a manner at once clear, accu- 

 rate, and entirely free from scientilie display, it cannot fail to com- 

 mand for itself the most extensive popularity. 



The Essay opens with an introductory chapter, chiefly explanatory 

 of the origin and general organization of the Survey, and then pro- 

 ceeds to discuss the various points of interest belonging to the fol- 

 lowing heads, each of which forms the subject of a separate chapter. 

 (1.) The Laurentine Mountains, and the range of the Laurentian 

 system generally. In a geological aspect, this zone of ancient me- 

 tamorphic and crystalline rocks divides the Province into two 

 broad districts, north and south : the latter being again subdivided 

 by an anticlinal, running from the Hudson valley and Lake Cham- 

 plain north-easterly towards Quebec, into an eastern and western 

 basin, each with special characteristics of its own. (2.) The Lau- 

 rentian system in its mineral and structural details. (3.) The Hu- 

 ronian system, the great copper-bearing region of the west, occupy- 

 ing a vast extent of country along the northern shores of Lake Hu- 

 ron and Lake Superior, and traversed by numerous dykes of trap. 

 (4 and 5.) The Palaeozoic rocks of the western basin, comprising, in 

 an ascending series, the Potsdam sandstone ; Calciferous Sand Bock ; 

 the Chazy, Bird's-eye, Black River and Trenton limestones : in places 

 so rich in fossils ; the Utica schist, with its peculiar trilobites ; the 

 Hudson River group ; the Medina sandstone, or base of the Upper 

 Silurians; the Clinton group; Niagara limestone; Onondaga salt 

 croup, with its gypsum beds and brine springs ; and finally the De- 

 vonian formations, comprising portions of the Helderberg series*, 



* The Oriskany sandstone and Corniferous limestone equivalents. The former feebly re- 

 presented. 



