Burning Clifs on the Mackenzie River. 563 



the chief part of the banks and also much of the undulated valleys 

 between the elevated spurs. It is based on horizontal beds of limestone 

 and in some places of sandstone. Covering the shaly beds, there 

 exists in many places a deposit of sand, sometimes cohering as a 

 friable sandstone. . . . The shale crumbles readily and often takes 

 fire spontaneously, occasioning the ruin of the bank ; it is only by 

 the encroachments of the river carrying away the debris that the true 

 structure is revealed." 



" When exposed for even a short time to the atmosphere, the coal, 

 which is probably all or mostly of Tertiary age, splits into rhomboidal 

 fragments, which again separate into thin layers, so that it is difficult 

 to preserve a piece large enough to show the woody structure in 

 perfection. Much of it falls eventually into a coarse powder ; and if 

 exposed to the action of moist air in the mass it takes fire and burns 

 with a fetid smell and little smoke or flame, leaving a brownish-red 

 ash, not one-tenth of the original bulk of coal taken from the purer 

 beds, for some contain much earthy matter." (p. 187.) 



" From the readiness with which the coal takes fire spontaneously, 

 the beds are destroyed as they become exposed to the atmosphere ; 

 and the bank is constantly crumbling down, so that it is only when 

 the debris has been washed away by the river that good sections are 

 exposed. The beds were on fire near Bear River when Sir Alexander 

 Mackenzie discovered them in 1785, and the smoke, with flames 

 visible by night, has been present in some part or other of the 

 formation ever since." (p. 188.) 



" Potter's clay, of a grey or brown colour, alternates with the beds 

 already named, in layers varying from one foot to forty or more in 

 thickness. This clay is often highlj^ bituminous, and is penetrated 

 by ramifications of carbonaceous matter, resembling the roots of 

 vegetables. About 10 miles above Great Bear Eiver, a layer of this 

 material, lying immediately over a bed of coal which was on fire, has 

 been baked so as to resemble a fine yellowish- coloured biscuit porcelain} 

 In a part of this I found numerous impressions of leaves, most of them" 

 Dicotyledonous, but one of them apparently coniferous and belonging 

 probably to the yew genus." (p. 190.) 



" Chief Factor Alexander Stewart told me that beds of coal are on 

 fire on the Smoking Eiver, which is a southern affluent of the Peace 

 Eiver, and crosses the 56th parallel of latitude, and also that others 

 exist on the borders of Lesser Slave Lake, that lies between Smoking 

 Eiver and Edmonton. There are coal beds on fire, also, at the present 

 time near Dunvegan on the main stream of the Peace Eiver. All 

 these places are near the base of the Eocky Mountains or the spurs 

 issuing from that chain, and their altitude above the sea varies from 

 1,800 to 2,000 feet and upwards. The beds at Great Bear Eiver are 

 probably not above 250 feet above the sea-level." (p. 195.) 



H.W. 



^ These porcellanous shales, with plant impressions of Tertiary Dicotyledonous 

 leaves, etc., collected by Sir John Richardson on the cliff banks of the Mackenzie 

 River from above the "burning coal-seams, are now preserved in the Geological 

 Department of the British Museum (Nat. Hist.), Cromwell Road. Many of the 

 species agree with those from the plant-beds of Atanekurdluk, Greenland. 



