238 ^ THE CARBONIFEROUS SYSTEM. 



Some specimens of the mineral are laminated, and have brilliant 

 discs about a line in diameter on the surfaces of the lamina. Under 

 the microscope, these discs exhibit very fine concentric and radiating 

 lines, but they are merely concretionary, and in Pictou coal such discs 

 sometimes occur in an oblique position as regards the lamination. 

 The Albertite has been declared to be free from sulphur ; but minute 

 concretions of ironstone and iron pyrites occur in it, and films of iron 

 pyrites line some of the fissures of the containing beds. These 

 appearances are, however, rare. 



In inquiring into the origin and mode of fonuation of the deposit, 

 the following alternatives present themselves : — (1.) It may have been 

 a bed or sheet of bituminous matter, thinning out at the edges, like 

 that in Kent, U.C., described in the Report of the Canadian Survey 

 for 1851-2,* and probably produced by the oxidation and hardening 

 of the liquid produce of naphtha- springs. (2.) It may be bituminous 

 matter melted by internal heat or fluid at ordinary temperatures, like 

 petroleum, and jDOured into an open fissure, and subsequently consoli- 

 dated, as was perhaps the case with the chajyapote of Cuba.-J- (3.) It 

 may, like jet and other coals, have resulted from the bituminization 

 of woody matter. With respect to these several hypotheses, I can 

 merely state the probabilities which occur to me from the facts already 

 known, and which may of course be greatly modified by the more 

 perfect exploration of the deposit. 



On the first of these hypotheses, though there is no great improba- 

 bility in supposing the deposit to have been a conformable bed, it does 

 not seem likely that so large and exti'emely pure a mass of bituminous 

 matter could be a deposit from springs, or that, without alteration of 

 the containing beds, it could have assumed an aspect and consistence 

 so much akin to those of coal. It also seems difiicult on this view to 

 account for the deposition, In waters tenanted by fish, of the accom- 

 panying laminated bituminous shales. 



The second view requires us to suppose that, after the cnimpling 

 and contortion of the beds, and the production of an open fissure, an 

 underlying portion of the bituminous shales was exposed to heat and 

 pressure, which caused Its bituminous Ingredient to be melted, forced 

 upward, and consolidated In the upper and unaltered portion of the 

 beds, or that the more liquid bituminous matter naturally oozed out of 

 the containing rocks. This would account for the occurrence and 

 most of the appearances of the coaly deposit ; but we must of course 

 still sujjpose that the bituminous matter was originally produced 

 during the deposition of the shales, probably from organic matter. 

 * Page 90. t Taylor, Statistics of Coal. 



