[ELLSj r#)ÏES ON THE MINERAL FUEL SUPPLY OF CANADA 289 



From a comparison of the coal-iields of the Atlantic areas with 

 those of the Pacific slope and even as far east as the great plains, it will 

 be readily seen that their geological horizons are quite distinct. Thus it 

 has been pointed out that all the western coals are of comparatively re- 

 cent date, while those of the east belong to the Carboniferous formation 

 and in places closely approach even the Devonian. This discrepancy in 

 horiaons continues southward throughout the United States into Mexico, 

 large deposits of coal, both of the bituminous and lignite varieties, oc- 

 curring in the area between the Mississippi and the Kocky mountains in 

 rocks of Cretaceous age, though in several of the states west of the Mis- 

 sissippi coals also occur in rocks of 'the Carboniferous formations. In 

 eastern Asia, in China and in Japan, immense deposits of excellent 

 bituminous coal are also found in the Cretaceous and Tertiary forma- 

 tions, in the latter of which also large quantities of petroleum occur. 



In eastern Canada, on the other hand the petroleum is principally 

 found in rocks of Devonian age, though the original source of this oil, 

 by those who advocate its organic origin, may be in some lower series; 

 while in the case of natural gas the largest occurrences are apparently 

 from Silurian rocks or possibly from even a lower horizon. In the west, 

 however, wherever oil or gas occurs it is found, like coal, in association 

 with the more recent formations, land .throughout the country of the 

 plains where boring for oil or gas is now being carried on a.nd where the 

 latter has been found in large .quantity as at Medicine Hat, and further 

 north along the lower Athabaska river, ^ucli borings have, all been con- 

 lined to the Cretaceous. The outflow of natural gas 'from the borings 

 made along the Athabaska in the Tar sand formation is something enor- 

 mous,! ^^^ force of the discharge 'being such that 'the drill rods could not 

 be sunk beyond! a certain, depth, though but little petroleum was encount- 

 ered. Natural gas in the country east of the Eocky mountains will 

 eventually become an important factor in the fuel supply of the west. It 

 has been found in large quantity as at Medicine Hat, Calgary, Edmon- 

 ton, and further north along the lower Athabaska river such borings 

 have all been confined to the Cretaceous, 



Although borings for oil have been carried on for several years 

 along the eastern flank of the mountains as in the Pincher Creek district 

 the strata have been too much tilted and faulted to serve as reservoirs 

 and the operations have so far not been crowned with success. The fact 

 that the oil-fields of Florence in Colorado are situated in rocks of the 

 same age as those which occur along the east side of the mountains in 

 what is known as the Pierre shale formation, lends strength to the sug- 

 gestion that at some time and in certain localities, similar oil-fields will 



Sec. IV., 1906. 24 



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