TJie Origin and Relations of the Carhon Minerals. :i85 



dei'ivcd in i:)art, at least, from animal organisms ; but the lime- 

 stones are generally compact, and if cellular, their cavities are 

 closed, and the amount of petroleum which, under any circum- 

 stances, flows from or can be extracted from limestone rock, is 

 small. On the other hand, the bituminous, shales Avhicli under- 

 lie the different oil regions, and are constantly associated with 

 the flow of the petroleum and carhuretted hydrogen, afford an 

 abundant source of supply, holding the proper relations with the 

 .reservoirs that contain the oil, and are spontaneously and con- 

 stantly evolving gaa and oil, as may be observed in a great num- 

 ber of localities. For this reason, while confessing the occurrence 

 of petroleum and asphaltum in many limestones, I am thorough- 

 ly convinced that little or none of the petroleum of commerce 

 is derived from them. 



Prof. S. F. Beckham, who has studied the petroleum field of 

 Southern California, attributes the abundant hydro-carbon ema- 

 nations in that locality to microscopic animals. It is quite 

 ])ossible that this is in part true in this and other localities ; but 

 the bituminous shales which are evidenily the sources of the 

 petroleum of Pennsylvania, Ohio, Kentucky, etc., generally 

 contain abundant impressions of sea-weeds, and indeed these are 

 almost the only organisms which have left any traces in them. 

 I am inclined therefore now, as in my report on the Rock Oils 

 of Ohio, published in 1860, to ascribe the carbonaceous matter 

 of the bituminous shales of Pennsylvania and Ohio, and hence 

 the petroleum derived from them, to the easily decomposed cell- 

 ular tissue of algae whicli have in their decomposition contrib- 

 ured a large percentage of diffused carbonaceous matter to the 

 sediments accumulating at the bottom of the water where they 

 grew. In a recent communication to the National Academy of 

 Sciences, Dr. T. Sterry Hunt has proposed the theory that 

 antliracite is the result of tlia decomposition of vegetable tissue 

 when buried in porous strata like sandstone ; but an examin- 

 ation of even a few of the important deposits of anthracite in 

 the world will show that no such relationship as he suggests 

 obtains. Anthracite may and does occur in sedimentary rocks 

 of varied character, but so far as my observation has extended, 

 never in quantity in sandstone. In the Lower Silurian rocks 

 anthracite occurs, both in the old world and in the new, where 



