THE OIL- AND GAS-PRODUCING ROCKS OF OHIO. 1 



This state began producing oil in i860. From that period 

 until 1885 the output was restricted to the eastern part of the 

 state, and was derived entirely from rocks of Carboniferous age. 

 The production during that time was relatively small, and of 

 little importance in a commercial sense. In 1885 the vast 

 repository in the Trenton limestone was discovered, and this at 

 once gave the industry in the state great impetus. The yield 

 was such that in 1895 ^ surpassed that of Pennsylvania and 

 New York combined, and since that date the state has held the 

 first rank. Gas first became an important fuel in Ohio in 1884, 

 the year of the great discovery at Findlay. From 1888 to 1900, 

 inclusive, the value of this product exceeded $28,000,000. 



The rocks, particularly the lower ones, producing these vast 

 supplies have been in part studied, especially by Orton, 2 but 

 thus far no paper has been published which considered all the 

 producing strata. It is the purpose of this article to enumerate 

 these, to discuss briefly their composition and general charac- 

 ters, and to show their stratigraphical position. 



THE ORDOVICIAN^ 



In Ohio the upper half only of this great division needs be 

 considered. This is divided by Orton as follows: 



3. Hudson River series - - - 300-750 feet 



2. Utica shales - - 0-300 



1. Trenton limestone - - - - 50 



The upper two members contain both oil and gas, but rarely 

 in commercial quantities. Occasionally high-pressure gas wells 

 are found, but these soon give out. Nowhere in Ohio can either 

 of these formations be regarded as a producer of natural gas. 

 Occasionally in the northwestern corner of the state oil is found 



1 Published by permission of Edward Orton, Jr., state geologist. 



2 Geological Survey of Ohio, Vol. VI, and First Annual Report ( 1890). 



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