Related Geological Conditions 55 



tlcally the whole world. While the detailed search for 

 these has gone forward rapidly, we still desiderate accu- 

 rate details as to the rocks that contain, or are near to, the 

 sources of the petroleum. But In many Instances we know 

 now that these are usually adjacent to beds that are rich 

 in fossil fish remains. 



But the writer now takes exception — as he will repeated- 

 ly do later — to a statement in Redwood's work (25 : 1 : 280) 

 and by implication to that of the other two authors cited, 

 which says regarding the possible origin of petroleum: 

 "The Engler-Hofer theory, as developed by its authors up 

 to the present time, states that petroleum is derived from 

 the natural decomposition in situ of the fatty remains of 

 marine organisms, both animal and vegetable." Up to 

 at least the Llassic period, we would distinctly affirm that 

 nearly all of the petroleum is the decomposition product 

 of freshwater fishes, and only from late Jurassic or early 

 Cretaceous times onward do marine fishes seem to have 

 contributed largely — In some cases perhaps entirely — to its 

 formation. 



That at least some species or even genera of fossil 

 fish were rich in products of an oily nature, throughout all 

 of the geologic formations, will be frequently emphasized 

 in later pages of this work. One of the many exact proofs 

 is, that often Isolated fossilized fishes are surrounded by 

 abundant oily products, that give a characteristic aspect and 

 odor to the enclosing block of rock. Again where masses 

 of ten to twenty are heaped together in a rock that other- 

 wise is sparcely fossiliferous, the area around the mass 

 specially shows an oily horizon. 



As to the exact manner In which the fat, oil, or other 

 more complex constituents of fishes may have contributed 

 to formation of petroleum. It might first be noted that in 

 the case of the living Protopterus "the nutrition of the 

 dormant fish is effected by the absorption of the fat stored 

 up about the kidnevs and gonads" (2:513). In contrast 

 to this, of Its ally Lepidosiren^ it has been said: "during 

 the rainy season the Lepidosiren eats voraciously, and a 

 reserve of fat Is stored up in the tissues. The great amount 

 present in the muscular tissues of fresh- and salt-water fishes 



