180 GEOLOGY OF OHIO. 
ern portion of London township, a coal is said to have been seen in plow- 
ing on top of high hills. If this be true, as is quite likely, the coal is 
the Pittsburgh or No. 8 of the Ohio section. Fragments of the limestone 
underlying that coal were observed at several points in these townships, 
showing that the coal at one time reached well up into this county. 
From this horizon downwards, about one hundred and thirty feet, to the 
Crinoidal limestone, the interval is occupied by sandstones and argilla- 
ceous shales, with a non-persistent limestone about midway, one foot 
thick, and non-fossiliferous. The Crinoidal limestone is well marked, but 
shows some interesting variations. It does not seem to reach further to 
the north-west than Carrollton, where it is seen only on the top of the 
ridge. On the road from that village to Harlem it is first seen at a dis- 
tance of about one mile. It is here very coarse grained, with a rude 
fracture like that of sandstone, and is not so rich in fossils as usual. A 
short distance beyond it resumes its ordinary character—dingy gray on 
the weathered surface—occurring in rude quadrangular blocks, and when 
broken showing a dull brown color. The fossils here are very numerous, 
but do not weather free from the rock, as they do not differ from it in 
hardness. The surface, consequently, is covered with sections of mollusca 
and crinoidal fragments, and only a few good specimens of Lophophyllum 
proliferum, Retzia punctilifera, and Athyris subtilita were obtained. The 
thickness of the stratum can not well be determined here, as there is 
no satisfactory exposure. Followed toward Harlem this limestone is 
seen to become double, the two layers separating more and more until, 
at Harlem, they are twenty-five feet apart, with Coal No. 7b between 
them. At this village the upper layer is fossiliferous, but differs from 
any other exposure, in that it contains much earthy matter and tends to 
disintegrate upon exposure to atmospheric influences. It is light blue 
in color, and is apparently free from iron, as the surface of fracture does 
not show the dull brown tint. The lower layer is thin, hardly one foot 
thick, and is non-fossiliferous. It is blue, breaks with a semi-conchoidal 
fracture, and rings clearly when struck with the hammer. In Perry 
township, between Perrysville and Palermo, both layers are even, with 
Coal No. 7b between them. The upper layer here shows none of the 
earthy character observed at Harlem, but is hard and flint-like, weather- 
_ ing into dingy nodules. It is so tough that it might be used with ad- 
vantage in macadamizing roads. This duplication of the stratum seems 
to be confined to Lee, London, and Perry townships, as it was not ob- 
served in Union, Center, Washington, or Fox. In the last two town- 
ships the stratum is admirably exposed along the ridge road from Car- 
rollton to Wattsville. It has been traced to the border of Columbiana 
