S. F. Peckham — Origin of Bitumens. 393 



My friend, Prof. Orton, has in the kindest manner shown that 

 in Ohio there is no evidence that any rocks are changed by 

 metamorphic action. While I do not for a moment think 

 Prof. Orton ever intended to be unjust to any one, I do think 

 he has hardly given either Dr. Newberry or myself the j)osition 

 that belongs to ns.* 



Wise men hold any theory tentatively, no matter what it 

 may be. When Dr. Newberry, in 1859, proposed to account 

 for the origin of petroleum by considering it to be a distillate, 

 very little was known concerning the occurrence of rock oil 

 compared with our present knowledge. When I prepared my 

 essay for the Census Report the Trenton limestone was almost 

 an unknown factor in the production of petroleum ; yet, 

 enough was known concerning its occurrence with oil in the 

 cavities of its fossils, to lead Dr. T. S terry Hunt, in the same 

 manner as other local observers ; to conclude that all petroleum 

 originated in limestone, in situ, and that the Trenton lime- 

 stone w&sjpar excellence the home of petroleum. f As I have 

 said before, when I left California in 1865, with the positive- 

 ness born of observation within a limited horizon, I was ready 

 to declare that petroleum was formed by the decomposition of 

 fossil animals. I first wrote the paper read at the meeting of 

 the National Academy of Sciences at Northampton, in 1867, 

 maintaining that narrow view; but 1 afterwards included veg- 

 etable remains as a precaution.^: It has been many times 

 demonstrated that each observer may be correct as to his own 

 locality and wrong as to others ; yet, when the consensus of 

 opinion has been reached, the symposium miy have presented 

 a many-sided question from many points of observation, and 

 truth may be discerned in the midst. 



I therefore repeat, that in my judgment the derivation of 

 petroleum has not been uniform. Let it be admitted that 

 the earliest horizon of petroleum is the Trenton Limestone, in 

 which petroleum is indigenous, having been formed by some 

 peculiar sort of decomposition from animal remains at the 

 bottom of a deep, excessively hot, and saline sea. If any one 

 can prove that the Trenton Limestone extends beneath eastern 

 Ohio and western Pennsylvania, lying beneath the Devonian 

 shales, I am not prepared to dispute the assertion that the 

 different varieties of petroleum found in that region have been 

 fractionally distilled from the content of the limestone rocks, 

 buried from three to four thousand feet beneath the present 

 surface. I am confident that the heat required was to be found 

 in the gradual dying out of the heated area which involved the 

 Appalachian System. Accompanying this distillation, and a 



* Rep. Geol. Surv. Ohio, vi, p. 60-83. 



f This Journal, II, xxxv, p. 157-168; xlvi, p. 361. % See note 1. 



