
Eee re Se ety ah mete ee ne yates 
é - . 
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VALUE OF LIGNITES AND IRONSTONES. 169 
which might have been of value to the future population of the North- 
west, is a matter of certainty. It would seem, however, that the com- 
bustion does not affect beds unless their edges have been laid bare to the 
weather by denudation; and the proportion thus exposed, in a country 
in which the strata are so nearly horizontal, must be small. The 
whole of the lignites, too, lying below the natural drainage level of the 
country must remain unaffected, and the fire would also seem unable to 
penetrate very far into a bed, unless it lies so near the surface as to be 
able to open communication with it, for the escape of its products of com- 
bustion, and to obtain a supply of oxygen. The face of the exposure, 
erumbling down on the ruins of the bed, must soon stop all access of air in 
that direction; though from the almost complete conservation of the heat 
of a combustion thus taking place in the mass of the formation, a very 
limited supply of air would be sufficient to maintain the necessary 
temperature. 
395. The only place in which the combustion was still found to be in 
progréss near the forty-ninth parallel, was in a locality on the Souris Ri- 
ver, and then it was only evidenced by the issue of a little smoke of a tarry 
empyrumatic odour. Other localities, from the immense amount of de- 
nudation which has taken place subsequent to the destruction of the lig- 
nite, show evidence that the fires have been extinct from a very remote 
period; though as a rule, in the region which I have examined, the pro- 
ducts of combustion appear to be pretty closely confined to the localities in 
which this can be proved to have taken place. Mr. Allen, however, has 
found “ this igneous material in a water-worn state, occurring in the drift 
which covers the general surface of the country, often many miles from 
the nearest seat of metamorphic action, as well as in the terraces that 
border the larger streams,” * and concludes that the combustion must 
have begun before the close of the drift period—a very important fact. 
Composition and Economic Value of the Lignites and Iron Ores. 
396. The following are proximate analyses of lignites from various 
localities in the vicinity of the forty-ninth parallel, and of the coal from 
St. Mary River. The greater part of these were published in the Report 
of Progress for the year 1873, already referred to :— 
397. Souris Valley. (§ 207.) Lowest lignite, two feet three inches 
thick. Conchoidal fracture with rather dull surfaces, and resembling 
cannel coal, ash reddish-white. 

*Loc, cit, 

