GEOLOGY. 261 



Hunt, of the Canada Survey, in the ' Geology of Canada,' p. 526, 

 dissents, and quotes approvingly the views of Mr. Wall, who 

 investigated the bitumens of Trinidad, and who writes that the 

 bitumen 'has undergone a special minerahzation, producing a 

 bituminous matter instead of coal or lignite. This operation is 

 not attributable to heat, nor of the nature of a distillation, but is 

 due to chemical reactions at the ordinary temperature and under 

 the normal conditions of climate.' It would appear to be Mr. 

 Hunt's opinion that the bitumens, of which petroleum is the liquid 

 form, are the product of chemical reactions changing the original 

 organic materials directly into oil and kindred hydrocarbons. . . . 

 There is no doubt that, at the original bituminization of organic 

 matter, vast quantities of bitumen were formed. The greater 

 portion of this was absorbed by the sediments wliich now consti- 

 tute bituminous strata. For examjjle, the black shales of the Ohio 

 Devonian rocks are two hundred and fifty feet thick, and in them the 

 bitumen is uniformly distributed throughout the whole mass. This 

 disti'ibution would imply that the bitumen was once in such a state 

 of fluidity as to allow it to diffuse itself. . , . All the oil that 

 I have ever seen, except very insignificant quantities in isolated 

 cavities in fossiliferous limestones, has evidently strayed far from 

 its place of origin. It is seldom, indeed, that we find any oil in 

 juxtaposition with bituminous strata of any kind. It is more often 

 found in fissures in sand-rocks, rocks in which no oil couUl ever 

 have been genei'ated ; for whatever organic matter they might 

 have contained was too much exposed to atmosjjheric ox3"gen to 

 admit of the possibility of any bituminization. It is not only im- 

 possible that the oil could have originated in these sand rocks, or 

 in the arenaceous shales which underlie them in western Pennsyl- 

 vania, but it is most probable that the oil ascended from the still 

 lower rocks, in the form of vapor, which condensed in the superior 

 cavities. In other words, the oil which, according to the theory, 

 was formed far below in the original bituminization of organic 

 matter, must have undergone a process of distillation. 



" In favor of the other theory, that petroleum, as now generally 

 found, is the product of a distillation of bituminous shales, etc., as 

 suggested by Dr. Newberry and others, the following arguments 

 may be urged : 1. Oil may be artificially produced by distilling 

 such shales and other bituminous materials. ... 2. The phe- 

 nomena of oil and gas exhibited in our oil fields greatly resemble 

 those observed in the artificial distillation of oil from bituminous 

 materials. . . . 3. It is believed that some petroleum has 

 been actually pi'oduced in the earth by distillation. ... 4. 

 There is an abundance of oil-making material in the earth. . . . 

 6. A comparatively low temperature is believed to be adequate to 

 set free the oil vapors. 6. By this theory there might be produced 

 an almost indefinite quantity of petroleum, since bituminous strata 

 are found widely distributed. . . . Finally, the agency which 

 would volatilize the liquid bitumen, or petroleum formed by direct 

 bituminization, and bring it up and distribute it through the pres- 

 ent oil horizons, would certainly be adequate to distil the bitumin- 

 ous shales, etc., and bring up the oil to the same elevations. 



