6io POPULAR SCIENCE MONTHLY. 



ture of the regions within which the new fields are embraced, 

 and the tracing of the chief factors that influence or control the 

 productiveness of the oil rock, with the description of the special 

 features and boundaries of the several fields and the setting forth 

 of the leading facts and present development of these lately found 

 sources of power. Two principal conditions under which the new 

 oil rock had proved petroliferous on a large scale were found to be 

 porosity, connected with and apparently dependent on the chemical 

 transformation of the upper portion of the limestone, for a number 

 of feet in thickness, into a highly crystalline dolomite; and a relief 

 resulting from slight warping of the strata, whereby the common 

 contents of the porous portions of the Trenton limestone had been 

 differentiated by gravity, the gas and oil seeking the highest levels, 

 and the salt water maintaining a lower but definite elevation in 

 every field. Professor Orton found nothing in the new experience 

 to make it safe to count the Trenton limestone an oil rock or a 

 gas rock in any locality, unless it could be shown to have under- 

 gone the dolomitic replacement by which its porosity was assured; 

 and even in case it had suffered this transformation it would not 

 be found a reservoir of gas or oil in an important sense unless 

 some parts of it had acquired the relief essential to the due separa- 

 tion of its liquid and gaseous contents. X 



The report on the Rock Waters of Ohio concerns, first, those 

 waters, chiefly in the northwestern and western part of the State, 

 that are obtained from a considerable depth as compared with ordi- 

 nary wells, the knowledge of which was almost wholly derived from 

 wells drilled in the search for oil and gas, and was necessarily frag- 

 mentary and incomplete; because water was not included among 

 the objects of search, but was considered a hindrance and obstruc- 

 tion to be got out of the way as well as possible; and, second, flow- 

 ing wells, including only those having considerable head of pres- 

 sure and those occurring in considerable areas, all of which belong 

 entirely to the drift. Further, a brief review is given of some facts 

 of unusual interest that were developed in the deep drillings con- 

 cerning the preglacial drainage system of the part of the State 

 in question. Indications of old river channels, one of which seems 

 to have been extensive, were found at several points. Among the 

 curious results of these studies was the conclusion, " seeming to 

 be already established," " that the Ohio River, as we now know 

 the stream, is of recent origin, and that the main volume of water 

 gathered in it at the present time originally flowed across the 

 State to the northward at least as far as Auglaize and Mercer 

 Counties, where it turned to the westward toward the present lines 

 of Wabash drainage in Indiana." Professor Orton seems to have 



