310 CHARLES: S” PROSSER 
gists have reported a white, sharp sandstone, 75 feet thick, the 
top of which is 313 feet below the base of the Sharon conglom- 
erate ;' which Mr. Carll regarded as probably identical with 
the Pithole grit of Pennsylvania and the Berea grit of Ohio.’ 
CONCLUSION. 
It has been shown in this article that the Sunbury shale is in 
general a well-marked and sharply-defined lithologic division, 
which extends from Vanceburg, in northern Kentucky, across 
Ohio to the eastern part of Trumbull county, and perhaps into 
Pennsylvania. It is usually thin, fissile, black, strongly bitumi- 
nous, varying in thickness from about 6 to nearly 28 feet. The 
lower part of the shale is very compact and tough, splitting into 
thin sheets of considerable size, which are somewhat arenaceous ; 
frequently containing some iron pyrites, and often rich in fossils, 
especially inarticulate Brachiopods. Near Bedford, in northern 
Ohio, however, it loses its decidedly black color, and is mainly 
bluish-gray or blackish-gray, with some blackish bituminous 
layers. The base of the shale is always sharply separated from 
the underlying massive Berea grit. At the top, wherever 
exposed, it is also, lithologically, clearly separated from the over- 
lying Cuyahoga formation, although the line of contact is not so 
well marked and conspicuous as the one at the base. In northern 
Ohio, at the base of the Cuyahoga formation, are bluish-gray 
alternating shales and thin sandstones, while in the bluffs of the 
Ohio river occur 5 feet of blue to drab “firey clay) andyshale, 
which is followed by 5 + feet of brownish to bluish-gray 
massive Buena Vista sandstone. Perhaps in Cuyahoga county 
the contact between the Sunbury and Cuyahoga shales is not 
so clearly defined as in most of the state, while again in 
Trumbull county and in the eastern part of the state there 
are bluish-gray to blackish shales in the lower part of the 
Cuyahoga formation, which resemble somewhat the subjacent 
t Second Geol. Surv. Pa., Q4, 1881, p. 70; also see I3, 1880, Atlas, Pl]. IV, Fig. 3, 
where the interval is given as 310 feet ; Q?, 1879, pp. 298, 303 ; and Q3, 1880, p. 119. 
2 Jbrd., 13, p. 93. 
