200 white: relations between coal and petroleum 



i 



Without going further, at this time, into details as to the 

 effects of folding and faulting in neutralizing the dynamic stresses, 

 attention is called to (a) the larger volatile content in those parts 

 of the anthracite fields that extend into the region of closer fold- 

 ing; (b) the anomalous variations seen in the Broadtop, the Coosa 

 and Cahaba basins which lie in fault blocks; and (c) the rela- 

 tively low stage of the alteration of the coals behind the Poca- 

 hont.as, the Pine Mountain and the Elk Valley overthrusts. 

 Undoubtedly the greatest intensity of initial stress has, in most 

 cases, been exerted where the strata are most folded and broken. 

 Where the stresses have been equal, it has been competency 

 versus compensation. The gradual absorption of the energy 

 of the westward movement by compression in the horizontal 

 series is shown by the westward decrease of minor folding, as 

 well as by the westward increase of volatile matter in the coals. 

 There is no visible evidence that igneous rock metamorphism 

 has caused any regional alteration of the coals in the Appalachian 

 trough. 



In the districts where high rank coals occur in the Cretaceous 

 and Tertiary formations of western America, the evidence of 

 the efficiency of thrust pressure, as the dynamic force causing 

 the chemical change of the coals, is hardly less evident than in 

 the Appalachian province, the phenomena being the same as 

 in the Paleozoic areas, though the ranges in rank are often greater. 

 In the western regions, the influence of igneous intrusives, which 

 are relatively numerous, is conspicuously restricted and ineffect- 

 ive in the regional sense, 



THE "dEVOLATILIZATION" OF THE ORGANIC DEBRIS 



In the laboratory methods of "approximate" analysis of coals 

 and other carbonaceous deposits, the oxygen, hydrogen, nitrogen 

 and a part of the carbon of the organic debris are distilled by 

 a dry and semi-open air process, the matter, eliminated in the 

 form of gases, being known as ''volatile matter." It seems to 

 be assumed that, in the geologic processes also, the substances 

 eliminated are all in gaseous form and, accordingly the results 

 are frequently described as the " devolatilization" of the organic 



