white: relations between coal and petroleum 195 



deposits, humic coals, cannel, boghead, etc., are, as has been 

 indicated, dependent upon (1) the kinds of original contributary, 

 organic material, their chemical compounds and the varying 

 proportions of the latter; and (2) the character and extent of 

 the microbian action, whose work depends, both as to extent 

 and as to character, on the kinds of host detritus and the con- 

 ditions of deposition. The latter embrace all environmental 

 factors, such as temperature, moisture, access of air, concentra- 

 tion of toxic biochemical products, etc., and flushing by water 

 drainage, on which, to some extent, rests the conservation of 

 the varied biochemical decomposition products, especially those 

 that are liquid or that enter into aqueous solution. All this 

 concerns merely the accumulation and more or less complete 

 decomposition of the organic debris in the form of peat, organic 

 muds, calcareous oozes and so forth. As soon as the organic 

 debris is buried and the oxygen so far exhausted that bacterial 

 action is no longer possible, or when toxicity puts an end to all 

 micro-organic action in the deposit, there comes the end to this, 

 the first stage in the formation of coal. This is the hiochemical 

 stage of coal formation. The exact point at which the biochemi- 

 cal process terminates has not been accurately observed in any 

 single case, but it appears to correspond approximately to the 

 burial of the peat and the complete smothering of the organic 

 matter in the mud, beneath superposed deposits. 



A fact which is most important is that, complicated and indis- 

 pensable as is this biochemical process, it appears to carry the 

 organic deposits little or no farther than the formation of peats 

 and organic muds, buried oozes, etc. 



The Dynamo-chemical Process 



Leaving now the work of the biochemical process in the for- 

 mation of coals and other carbonaceous sedimentary deposits, 

 we pass to the consideration of the alteratiqn of these deposits 

 to coals and hydrocarbon rocks of higher ranks, as a result of 

 geo-dynamic action. We have now to do with the changes in 

 the physical and chemical characters of the organic matter, 

 accomplished through the dynamo-chemical process or the sec- 

 ond stage in coal formation. 



