Possibilities of the Oil Resources of Canada 45 



A large area is underlain by Devonian beds that exhibit a very slight 

 degree of folding. This area extends from the Rocky Mountains east- 

 ward to the granite areas of the Canadian shield. The relief is generally 

 low and includes the Mackenzie valley. The disturbance which is 

 marked by the upthrust of the Rocky Mountains extended into the area 

 but with lessening force. A major fold or break crosses the valley from 

 south to north, dividing it into two distinct basins differing in structure. 

 The area east of this fold and extending to Great Slave lake and Great 

 Bear lake is a plain bounded on the south by the edge of the plateau built 

 up of Cretaceous sediments, on the west by the Nahanni mountains, and 

 on the northeast by the mamillated surface of the Archaean rocks. The 

 outcrop of the middle Devonian sediments on Slave lake shows several 

 oil springs. The rocks dip slightly to the southwest and seem to offer 

 a large field for prospecting. 



To the west of the dividing fold, noted above as the Nahanni Moun- 

 tains, and along the lower part of the Mackenzie valley, the sediments 

 show a series of strong folds and oil seeps are quite com,mon. In both 

 these fields thpre seem to be great masses of oil-saturated shales and 

 porous dolomites from which oil is expected to be obtained by drilling. 

 Should the drilling of the favourable structures not prove the presence of 

 a fluid oil in commercial quantities, the reserve of oil in the shales should 

 in itself be of great importance. 



Arctic Islands. 



The northward continuation of the strata exposed in the Mackenzie 

 valley is exhibited on several of the outer islands of the group. The 

 structure of the islands exhibits very little of the compressive strains of 

 the continent. Normal faulting probably is indicates as being the basis of 

 the geographic features. The blocks which form the islands show the 

 beds dipping at slight angles to the northwest and north. In rocks of 

 Carboniferous age, shales or cannel coals which appear to have a value 

 as oil shales have been found on Melville island. The measures in which 

 these occur are thought to thin out toward the east, as on Elesmere island 

 they appear to be wanting. The rocks there exposed are mapped as 

 Triassic overlying Devonian. 



James Bay Basin. 



Aji area of Devonian rocks to the south of the bay forms a small 

 prospective area in which oil or oil shales may be discovered. 



