MODERN THEORY OF ORIGIN 729 



which show that the organic deposits composed most complete!}^ of waxy 

 spores, resins, fatty products, gelatinous algae, and other associated or- 

 ganisms and their decomposition products will, when distilled, yield pe- 

 troleums nearest typical and of higher ranks. This fact, which was 

 demonstrated by Eenanlt^ and C. E. Bertrand,'' and given practical inter- 

 pretation by Potonie,^ seems now to have won Engler,^ among others. It 

 may be noted that the rich oil shales of the Green Elver Eocene forma- 

 tion in the Uinta Basin of Colorado and Utah were found by the late C. A. 

 Davis, who was studying them, to consist largely of spores, algae, fungi, 

 etcetera, mingled with the debris of other vegetable and animal types. 



The organic muds destined to form the mother rocks of petroleum were 

 deposited in both saline and fresh waters; but while it is probable that 

 certain types or certain characters of the oils were predetermined by the 

 characters of tlie organic debris and the conditions of its deposition, in- 

 cluding the duration of the anaerobic action, the special office attributed 

 by some chemists, including Ochsenius, to the presence of salt in the gen- 

 eration of petroleum remains to be demonstrated. Even as a preserva- 

 tive tending to retard the decay of the organic detritus, as suggested by 

 Zaloziecki,^^ its value is doubtful, for marine bacteria are as numerous 

 and as efficient as those in fresh water, and it is well known that the de- 

 struction of animal matter in the ocean is not less rapid and complete 

 than in lakes and ponds. In fact, it appears generally to l)e more com- 

 plete. The sulphur in the Trenton and other marine limestone oils was 

 probably yielded by the decomposition of marine animal organisms, only 

 to be gathered again in the organic mud through the action of the sul- 

 phur bacteria, which are more common in the salt water. From the ma- 

 rine deposits, which are thus rich in sulphur, the latter has probably been 

 taken in greater amounts by the oils. However, in other cases, as has 

 recently been pointed out by Mabery, and fully established by G. S. Eogers 

 in the Coalinga region of California, the sulphur is carried as sulphates 

 in downward percolating waters, and liberated as hydrogen sulphide or 

 free sulphur on reaching the first zone of the hydrocarbons, below which 

 sulphates are absent. The tendency of oils to take up sulphur to their 

 great deterioration has l)een strongly emphasized by Mabery.^^ The dis- 

 appearance of the sulphates on reaching the hydrocarbon zone accounts 

 also for their absence, as remarked by Thompson, in the underlying sands. 



« Micro-organismes des Combustibles Fossiles. Comptes Rendus, vol. 117, 1893, p. 593. 



■^ Comptes Rendus Congr. Geol. Internat, 1900, p. 4.58. 



8 Entstehung d. Steinkohle. 5th ed., 1910, p. 95. 



" Engler and Hofer, Das Erdol, vol. 2, 1909, p. 59. 



10 Chem.-Zeit, vol. 15, 1891, p. 1203. 



"Econ. Geology, vol. 11. no. 6, 1916, p. 526. 



