828 /. A. BOWNOCKER 



None of these formations produce oil, and the Ohio shales 

 alone yield gas. The available supply of this, however is very 

 small, and its use has been limited to domestic purposes. The 

 principal counties have been those along the lake shore in the 

 northeastern corner of the state. These shales, which underlie 

 the eastern half of the state, are wedge-shaped, with the apex 

 reaching from the lake to the Ohio. The cities, Columbus, 

 Delaware, and Bucyrus, lie on or near this apex. Eastward 

 the formation thickens rapidly and near Wellsville on the Ohio 

 river has been penetrated to a depth of 2,600 feet without 

 reaching the base. This feature has led to much confusion on 

 the part of the driller, who has expected to find the interval 

 between the Berea grit and the Devonian limestone, the same in 

 the eastern part of the state that he did in the central. 



The gas secured in these shales is not from any one horizon, 

 but varies stratigraphically from place to place. The wells are 

 all small. Very commonly the shales make a show of gas, but 

 usually the yield is so light as to be commercially valueless. 

 The aggregate amount contained, however, must be very large, 

 and if it could be collected would form one of the most valuable 

 supplies of fuel in the state. 1 



THE CARBONIFEROUS. 



Classifying the formations of this great division, as has been 

 customary, into the Lower Carboniferous, Coal-measures, and 

 Permian, it is found that the oil- and gas-bearing rocks are 

 restricted to the first two members. These will now be con- 

 sidered in order. 



I. THE LOWER CARBONIFEROUS. 



The Berea grit. — This is the most extensive sandstone of the 

 state. Its area above and below drainage is about 15,000 square 

 miles, or more than one-third of the area of the state. Its value 

 is commensurate with its extent. " Its economic value above 

 ground is great, but it is greater below. In its outcrop it is a 

 source of the finest building-stone and the best grindstone grit 



'For a full discussion of this subject see Geological Survey of Ohio, Vol. VI. pp. 

 410-42. 



