86 DEPARTMENT OF THE INTERIOR 



2 GEORGE V., A. 1912 



Fifty miles north-northwest of the Boundary section through the Clarke 

 range, the Livingstone range is adjoined on the west by the well known Crowsnest 

 geosynclinal, containing from 12,000 to 13,000 feet of Cretaceous rocks, with 

 possibly some conformable Jurassic beds at the base of the series.f This 

 intermont development of the Cretaceous has no equivalent at the Forty-ninth 

 Parallel unless it be represented in deeply buried strata beneath the Miocene 

 of the Flathead fault-trough now to be described. Elsewhere in the Boundary 

 belt the pre-Mesozoic terrane of the Front ranges is nowhere seen to be overlain 

 by the Cretaceous, though it underlies the planes of the Lewis thrust and other 

 contemporaneous major thrusts of the region. (See page 90.) 



In the Little Belt mountains of Montana the Cretaceous beds lie conform- 

 ably upon the thin Ellis formation which is assigned to the Jurassic. The Ellis 

 formation in turn rests with apparent conformity upon Mississippian 

 group of strata.:}: The relations are similar to those which obtain at the Crows- 

 nest Pass section, to which reference has been made. A hundred miles farther 

 north, at Moose mountain, and again at the Lake Minnewanka section, Dowling 

 has recently found the conformable Cretaceous- Jurassic series resting directly 

 upon the Mississippian limestone.§ At the latter point and at many others 

 McConnell and Dawson have described the Cretaceous as lying, always with 

 apparent conformity, upon the Carboniferous formation. These occurrences on 

 both sides of the Boundary line, comparatively near to it, and all located on 

 the line of strike of the Front ranges at the Forty-ninth Parallel, make it 

 highly probable that the same general relation holds within the Boundary belt 

 or its immediate, eastward extension. It will be noted that the Jurassic beds 

 are generally of no great thickness and there is no certainty that they are repre- 

 sented in the Boundary line section at any point. If they are absent the Cre- 

 taceous may be regarded as resting on an erosion-surface terminating the 

 Carboniferous limestone; it is further probable that the Carboniferous beds were 

 little, if any, folded before the Cretaceous beds were deposited. The pre-Creta- 

 ceous erosion of these Paleozoic rocks at the Forty-ninth Parallel seems, then, 

 to have followed a gentle, broad upwarp of the eastern part of the Cordillera. 



KISHENEHN FOKMATION. 



The floor of the wide Flathead trough at the Boundary line is generally 

 covered with glacial drift of extraordinary thickness and continuity. In the 

 northern half of the five-mile belt the river has cut through the drift sheet. 

 The bed-rock thus exposed may be seen at intervals in the low bluffs extending 

 about three miles northward from the Boundary slash. Throughout that 

 stretch the bed-rock belongs to a Tertiary fresh-water deposit which is not known 

 to have an exact stratigraphic equivalent anywhere else in the area covered by 



t J. McEvoy, Annual Export, Canadian Geological Survey for 1900, Vol. 13, Ottawa, 

 1903, page 90a. 



X W. H. Weed, Little Belt Mountains folio, U. S. Geol. Survey. 

 § D. B. Dowling, Bull. Geol. Soc. America, Vol. 17, 1906. p. 295. 



