oe, ANNUAL REPORT 
None of these formations produce o:l, 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 con- 
tained, 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 cus- 
tomary, 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 considered 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 of the country, and when it dips beneath the surface 
it becomes the repository of invaluable supplies of petroleum, gas and 
salt water.” 
The composition and structure are very constant. The color is 
gray below drainage, but has a tinge of yellow above. The sand is of 
moderate fineness, and composed almost wholly of silica. Occasionally 
it contains carbonate of lime, probably as a cement, but this never consti- 
tutes more than a very small fraction of the formation. That found 
1For a full discussion of this subject see Geological Survey of Ohio, Vol. 
VI, pp. 410-442. 
21bid., Vol. VII, p. 28. 
