156 GEOLOGY OF OHIO. 
In western Columbiana county the Barren Measures are finely shown 
in the range of high hills which border Yellow Creek. The section here 
shows most of this lower coal group well developed; about Hammonds-. 
ville, Nos. 3, 4,5, 6, and 7, all of workable thickness ; at Salineville, coals 
Nos. 6 and 7 only above drainage. Over these the hills rise to the height 
of 850 feet, and are for the most part composed of gray, yellow, and red 
shales; the latter predominating and giving a marked character to the 
landscape. Two thin seams of coal are here seen in the Barren Meas- 
- ures, but neither more than a few inches thick. Of these the upper lies 
_ just over the crinoidal limestone at a distance of about 250 feet above the 
Salineville Strip vein (No. 7). This crinoidal limestone is one of the 
most constant elements in the Barren Measures, as it runs through the 
entire series of counties underlaid by this group. This is Prof. An- 
drews’s Ames limestone, and is frequently mentioned in his reports on the 
southern counties. Its normal place is 140 to 150 feet below the Pitts- 
burgh coal ;* and in the central and southern portions of the State it is 
so constant in its presence and position that it forms a most useful guide. 
This is illustrated by the fact that the late Prof. Hodge, when con- 
nected with the survey, in making a reconnoisance of Jefferson, Harrison, 
and Carroll counties, used to call it the “blessed little limestone,” thereby 
expressing his appreciation of its usefulness and reliability as a geologi- 
cal guide. In south-eastern Ohio the Ames limestone is reported by 
Prof. Andrews to be as universal in its distribution and as inflexible in 
its position as farther north. It also has considerable paleontological 
interest, as it has furnished us a long list of fossils, which will be found 
enumerated in the reports of Prof. Stevenson. These are for the most 
part species common to other portions of the Coal Measures, but among 
them are some fish teeth which I have obtained from no other stratum. 
These are Petalodus Alleghaniensis and Peripristis, n. sp. I have also col- 
lected these fossils from the same limestone at Pittsburgh, and they may 
perhaps be characteristic of it. 
In central and southern Ohio the Barren Measures are less barren than 
farther north and east. The beds of coal which occur in them are more 
numerous, and they locally attain, in several instances, workable dimen- 
sions. They are, however, much smaller and less continuous than those 
of the lower or upper groups. In Carroll county one of these coals is 
seen at Harlem Springs, and is called the Harlem coal. It is mined in 
* This interval increases, however, toward the east. At Steubenville the crinoidal ~ 
limestone is 225 feet below the Pittsburgh coal, and in western Pennsylvania it be- 
comes 350 feet before the limestone is lost sight of. 
