286 The Origin and Relations of the Carton Minerals. 



no metamorphisin has affected it and where it is simply the 

 normal result of the long continued distillation of plant tissue, 

 hut the anthracite beds which are known and mined in so many 

 countries are the results of the metamorphism of coal-beds of 

 one or another age, by local outbursts of trap, or the steaming 

 and baking of the disturbed strata in mountain chains — nume- 

 rous instances of which are given on a preceding page. 



Mr. M. Mendeleeff, in his article already referred to, misled 

 by want of knowledge of the geology of our oil-fields, and as- 

 cribing the petroleum to an inorganic cause, connects the pro- 

 duction of oil in Pennsylvania and Caucasia with the neighboring 

 mountain chains of the Alleghanies and the Caucasus ; but in 

 all such localities, a sufficient amount of organic matter can be 

 found to supply a source for the petroleum, while the upheaval 

 and loosening of the strata along lines parallel with the axes of 

 elevation in mountain chains has favored the decomjiosition 

 (spontaneous distillation) of the carbonaceous strata. It should 

 be distinctly stated, however, that no igneous rocks are found 

 in the vicinity of productive oil-wells, here or elsewhere, and 

 there are no facts to sustain the view that petroleum is a vol- 

 canic product. 



In the valley of the Mississippi, in Ohio, Illinois and Ken- 

 tucky, are great deposits of petroleum very far removed from 

 any mountain-chain or volcanic vent, and the cases which have 

 been cited of the limited production of hydro carbons in the 

 vicinity of, and jn'obably in connection with, volcanic centres, 

 may be explained by supposing that in these cases the petro- 

 leum is distilled from sedimentary strata, containing organic 

 matter affected by the proximity of melted rock or steam. 

 Everything indicates that the distillation which produces tha 

 greatest quantities of petroleum known is effected at a low tem- 

 perature, and the constant escape of petroleum and carbu retted 

 hydrogen from the outcrops of bituminous shales, as well as the 

 result of weathering on the shales, depriving them of all their 

 carbon, shows that the distillation and complete elemination of 

 the organic matter they contain may take place at the ordinary 

 temperature. 



