190 "WHITE: EELATIONS BETWEEN COAL AND PETROLEUM 



origin, as, for example, by the contact of percolating waters 

 with deep-seated metalHc carbides. The observations presently 

 to be noted bear unfavorably on the theory of the inorganic 

 origin of petroleum. The arguments both for and against all 

 variants of the inorganic theory have been fully summarized 

 by many geologists, both American and foreign, ^ and will not 

 receive further attention in this paper, the aim of which is to 

 throw additional light, from the geological standpoint, on the 

 origin of petroleum. 



THE INGREDIENT MATERIALS OF COALS AND OIL ROCKS 



It is now almost universally agreed that coal of different kinds 

 had its beginning as relatively pure deposits of more or less 

 decomposed organic debris derived mainly from vascular plants. 

 Coals of the common or humic types had their beginning as 

 peats, mainly freshwater peats, those of the great coal fields 

 having been, for the most part, laid down in great swamps or 

 estuarine marshes."* The type of the coal — namely, whether it 

 be xyloid, ^'amorphous," cannel, etc. — depends on the kinds of 

 ingredient organic matter and on the conditions controlling the 

 deposition of this matter. The common types are, to a great 

 extent, composed of the remains of woody plants, portions of 

 which are readily visible to the unaided eye. The more dis- 

 tinctly xyloid coals are largely made up of somewhat altered, 

 but more or less readily recognizable wood, which may con- 

 stitute more than 80 per cent^ of the mass. Wherever the con- 

 ditions of decomposition have been favorable for a more advanced 

 disintegration of the debris through the action of micro-organ- 

 isms, of which the most important are the bacteria, megascopic 

 wood in the peat or coal is not so abundant; and where the 



3 See: Peckham, S. F., Tenth Census Report, 10: 59. 1884; Orton, Edward, 

 Gaol. Surv. Kentucky, Report on the occurrence of petroleum, natural gas and 

 asphalt rock in western Kentucky, p. 31. 1891 ; Haworth, Erasmus, Kansas Univ. 

 Geol. Surv., 9: 187. 1908; Engler, C, and Hofer, Hans v., Das Erdol, 2: 59. 

 1909; Clarke, F. W., U. S. Geol. Surv.^ Bull. 491: 693. 1911; Hofer, Hans, Das 

 Erdol und seine Verwandten, p. 214, 1912; Redwood, Boverton, Petroleum, 3rd 

 ed., 1: 268. 1913. 



* White, D., Bur. of Mines, Bull. 38: 62. 1913. 



^ Thiessen, R., Log. cit., p. 221. 1913. 



