224 GEOLOGY OF OHIO. 



a thin streak of coal, which, however, is of no value in this county. In 

 no other portion of the county was this limestone observed. 



Coal No. 7a is of value only in Liberty, Jefferson, and Monroe town- 

 ships, where it is between three and four feet thick, and in these town- 

 ships is used only because no other coal is accessible. Usually it is of 

 poor quality. Overlying it is a heavy sandstone, containing many vege- 

 table remains, and apt to be conglomerate. As in Harrison county, iron 

 ore is not unfrequently found above this bed, but, as far as observed, the 

 quantity is unimportant. Occasionally, blackband is found over No. 76, 

 and that may prove to be an ore horizon of some local value. 



Coal No. 7 is of little importance north of the Central Ohio Railroad, 

 and its variations are exceedingly perplexing. At one locality it is five 

 feet thick ; two miles north-west it is eight inches ; three miles farther 

 north it is thiee feet ; after which to the north it varies from ten to 

 eighteen inches. It can be traced through Cambridge, Center, Liberty, 

 Monroe, and Adams townships, but is worked only in Center and Cam- 

 bridge. South of the railroad it is of considerable value. The sandstone 

 above this bed is very massive, and apt to be conglomerate. The shales 

 resting on the coal are dark-colored, and occasionally become true black- 

 band. 



Coal No. 6 was observed onlj- in Liberty, Wheeling, and Knox town- 

 ships, in each of which it is extensively worked for domestic use. It varies 

 from thirty-three inches in Liberty to four feet in Knox. The coal is 

 usually of good quality. The shales overlying it are full of ferruginous 

 nodules, having fragments of zinc blende as their nuclei. At the junc- 

 tion of the shales with the sandstone above a large quantity of nodular 

 iron ore occurs, but it is so intimately associated with the sandstone as to 

 be practically worthless. 



Coal No. 4 was seen at several localities in Liberty and Wheeling town- 

 ships. The gray limestone above it contains great numbers of Spirijer 

 lineatus, and is not persistent. The coal varies from eighteen inches to 

 five feet, and is worked only in Liberty township. The distance between 

 this bed and No. 6 is very variable in this county, and equally so in Mus- 

 kingum county, as will be seen by reference to that report. In south- 

 east Liberty No. 4 is only twenty-eight feet below No. 6. Five miles to 

 the north-west the distance is somewhat more than forty feet ; while five 

 miles farther to the north-west it is one hundred and five feet. This evi- 

 dently shows that the subsidence which put a stop to the formation of 

 a coal-bed bore no fixed relation in its local extent to the length of time 

 intervening before the formation of the next bed above. 



Coal No. 3 was seen only in Wheeling township, the blue limestone 



