248 



The Ottawa Naturalist. 



[January 



on these older rocks. The two maps, constituting what are 

 known as sheets Nos. 131 and 138 of the Canadian Series, lie in 

 the Upper Ottawa district along the border of the two provinces 

 of Quebec and Ontario, and comprise portions of both. Lake 

 Nipissing- and Lakes Temagami, Temiscaming and Keepawa, as 

 well as many smaller bodies of water, are included in the area, 

 and afford along their shores especially good opportunities for the 

 prosecution of geological work. 



After presenting a general account of the early explorations 

 in this region, some of which date back almost to the time of the 

 earliest settlement of the country by the French, and of previous 

 surveys, the physical features of the country are described. The 

 area is a great uneven or gently undulating rocky plateau, sloping 

 somewhat to the east and northeast, having a general elevation of 

 of 900 to 1200 feet above sea-level, the level being so nearly 

 uniform that hills 50 to 100 feet higher are conspicuous topo- 

 graphical features. This peneplain is traversed in a north and 

 south direction along one line of a very deep and rocky gorge, in 

 which lie Lake Temiscaming and the Ottawa River. The hills, or 

 cliffs, rise to a height of 400 to 600 feet from the water on either 

 side, while the water of the lake is 400 feet deep, the bottom of 

 the gorge being filled with a fine silt. The depression is thus 

 1000 feet deep and represents a great canon similar to those which 

 are found on the margin of the northern protaxis at so man) other 

 points. Several smaller rivers also occ\ipy similar depressions. 

 "The detailed examination of the region, however, amply demon- 

 strates that the sculpturing to which the surface owes its present 

 configuration was practically completed long before the advent of 

 the glacial epoch, and that the main valleys, especially those of 

 the Ottawa and Mattawa rivers, were in existence long prior to 

 the deposition of the Palaeozoic sediments." With the exception 

 of some comparatively small areas occupied by Palaeozoic outliers, 

 ranging in age from Black River to Niagara, the district is under- 

 lain by rocks of Laurentian and Huronian age. The Laurentian, 

 with the exception of a few small occurrences, is represented 

 exclusively by the Fundamental Gneiss, a mass ol granitic and 

 dioritic rocks, usually possessing a foliated structure in which are 

 many streak^, bands or inclusions of basic character, allied to 



