284 Tlie Origin and Relations of the Carbon Minerals. 



Among those wlio are agreed as to the organic origin of the 

 hydro-carbons, there is yet some diversity of opinion in regard 

 to the nature of the process by which they have been produced. 



Prof, J. P. Lesley has at various times advocated the theory 

 that petroleum is. indigenous in the sand-rocks which liold it, 

 and has been derived from plants buried in them. (Proc. Amer. 

 Philos. Soc, Vol. X, pp. 33, 187, etc.) 



My own observations do not sanction this view, as the number 

 of plants buried in the sandstones of the Coal measures or the 

 Conglomerate must always have borne a small proportion in 

 volume to the mass of inorganic matter; and some of those 

 which are saturated with petroleum are almost completely des- 

 titute of the impressions of plants. 



In all cases where sandstones contain petroleum in quantity, 

 I think it will be found that there are sheets of carbonaceous 

 matter beloAV, from which carburetted hydrogen and petroleum 

 are constantly issuing. A more probable exj^lanation of the 

 occurrence of petroleum in the sandstones, is that they have, 

 from their porosity, become convenient receptacles for that 

 which flowed from some organic stratum below. 



Dr. T. Sterry Hunt has regarded limestones, and and especi- 

 ally the Niagara and Corniferous, as the principal sources of 

 our petroleum ; but, as I have elsewhere suggested, no con- 

 siderable flow of petroleum has ever been obtained from the 

 Niagara limestone, though, as at Chicago and Niagara Falls, it 

 contains a large quantity of bituminous matter ; also, that the 

 Corniferous limestone which Dr. Hunt has regarded as the source 

 of the oil of Canada and Pennsylvania, is too thin, and too 

 barren of petroleum, or the material out of which it is made, to 

 justify the inference. 



The Corniferous limestone is never more than fifty or sixty 

 feet thick, and does not contain even one per cent, of hydro- 

 carbons ; and in southern Kentucky, where oil is produced in 

 large quantity, this limestone does not exist. 



That many limestones are more or less charged with petro- 

 leum is well-kiiown ; and in addition to those mentioned above, 

 the Silurian limestone at Collingwood, Canada, may be cited as 

 an example; and as I have elsewhere shown, we have reason to 

 believe that the petroleum here is indigenous, and has been 



