20 ANNUAL REPORT 
The Clinton.—Of these divisions, the second and fourth only call 
for recognition in this chapter. Along its line of outcrop in southwestern 
Ohio, the Clinton consists essentially of a highly crystalline limestone, 
rich in fossils, especially crinoid stems. Commonly it has a light color, 
the tint of which varies from place to place. The rock takes a good 
polish, and is sometimes.called marble. Occasionally the formation con- 
tains lean hematite, and one of the earliest blast furnaces in the state 
1elied.on this ore. In composition the rock is calcareous, and at one 
point becomes the purest rock of this type in the state. 
~ Northward, under cover,the rock undergoes notable changes, the re- 
sult being that it closely resembles the overlying Niagara. It is in the 
central portion of the state, however, that the greatest change is found. 
Instead of a well-marked limestone, there is found in its place shales of 
different colors and composition and a conspicuous sandstone; the latter 
the repository for the great reservoirs of gas in Fairfield, Hocking, Lick- 
ing and Knox counties. In northern Vinton county a pool of oil also has 
lately been found, and one well has been secured in Perry county. 
The relations of these beds to the overlying Niagara are shown in 
the following partial log of a well on the Bauer farm, near Sugar Grove. 
Samples of drillings below the Niagara were taken by the writer: 
Feet 
: top at 620 
BOLO OTE inchs: ean Ne euansior ones iene reeks rie eetneTe - 
nif | bottom at 645 
Corniferous, Helderberg, top at 1,430 
and ‘Niagara limestones. :....:...¢...0.... bottom at 2,132 
{ Shales, light chocolate-colored. top at 2,132 
| Little linie ; 3. eae bottom at 2,168 
Shales, green and chocolate-colored, top at 2.168 
the latter fossiliferous. Some lime. bottom at 2,199 
Clinton 
4 
| Shales, green and chocolate-colored. top at 2,199 
MCh iM Greer eee ee hes eee cna hottom at 2,236 
@Glintonweandit. se ee eee 2,236 
Generally when the gas sand has been penetrated to a depth of 
from 10 to 15 feet the drill is stopped, and consequently data farther 
down are less abundant. In western Ohio the basal portion of the 
Niagara is commonly occupied by shales,! but northward and eastward 
this member contracts. In central Ohio it consists of shales and thin beds 
of limestone, and the bottom of these is regarded as the line of junction 
of the Niagara and the Clinton. 
1Geol. Survey of Ohio, Vol. VII, pp. 11-18. 
