G. M. Dawson — Geology of British Columbia. 215 



have been much reduced by denudation. Their most important 

 area, including the coal-mining regions of Nanaimo and Comox, 

 may be described as forming a narrow trough along the north-east 

 border of Vancouver Island, 130 miles in length. The rocks are 

 sandstones, conglomerates, and shales. They hold abundance of 

 fossil plants and marine shells in some places, and in appearance 

 and degree of induration much resemble the true Carboniferous 

 rocks of some parts of Eastern America. In the Nanaimo area the 

 formation has been divided by Mr. J. Eichardson as follows, in 

 descending order : — 



Sandstones, conglomerates, and shales 3290 feet. 



Shales 660 „ 



Productive Coal-measures 1316 ,, 



5266 

 The last named consists of sandstones and shales, and holds 

 valuable coal-seams near its base. In the Comox area seven well- 

 marked subdivisions occur, constituting a total thickness of 4911 feet. 



Upper conglomerate . . . , 320 feet. 



Upper shales 776 ,, 



Middle conglomerate 11"0 ,, 



Middle shales 76 „ 



Lower conglomerate 900 ,, 



Lower shales 1000 ,, 



Productive Coal-measures 739 ,, 



4911 



The fuel obtained from these measures is a true bituminous coal, 

 with — according to the analysis of Dr. Harrington — an average of 

 6-29 per cent, of ash, and 147 per cent, of water. It is admirably 

 suited for most ordinary purposes, and is largely exported, chiefly 

 to San Francisco, where, notwithstanding a heavy duty, it competes 

 successfully with coals from the west coast of the United States, 

 owing to its superior quality. The output of 1879 amounted to 

 24:1,000 tons, and is yearly increasing. 



In addition to the main area of Cretaceous rocks above described, 

 there are numerous smaller patches, holding more or less coal, in 

 different parts of Vancouver Island, several of which may yet prove 

 important. 



In the Queen Charlotte Islands, Cretaceous rocks cover a consider- 

 able area on the east coast, near Cumshewa and Skidegate Inlets. 

 At Skidegate they hold true anthracite coal, which, besides being a 

 circumstance of considerable geological interest, would become, if 

 a really workable bed could be proved, a matter of great economic 

 importance to the Pacific coast. 



At Skidegate, where these rocks are most typically developed, they 

 admit of subdivision as follows, the order being, as before, descending : 



A. Upper shales and sandstones 1500 feet. 



B. Coarse conglomerates 2000 ,, 



C. Lower shales with coal and clay ironstone 5000 ,, 



D. Agglomerates 3500 ,, 



E. Lower sandstones 1000 ,, 



13,000 



