724 GEOLOGY OF OHIO. 



tance from the Pittsburgh coal to the crinoidal limestone is 207 feet, and 

 to the shaft coal is 511 feet. At LaGrange the interval is 540 to 550 feet. 

 The interval between Coals No. 6 and No. 8 is 512 feet, as measured by 

 barometer. 



The hills which form the banks of the Ohio at Pittsburgh are geo- 

 logically the same as those at Steubenville, and those who have noticed 

 the great thickness of olive and gray shales which chiefly form them, 

 with nothing of interest or value below the Pittsburgh coal and above 

 the Ohio, will perceive the appropriateness of the term chosen by Prof 

 Rogers to designate them. 



As has been stated, the coals of the Barren Measures are generally of 

 little or no value, but on Wills Creek the coal under the crinoidal lime- 

 stone, about two hundred and twenty-five feet below the Pittsburgh 

 seam, is two and a half feet in thickness, and of very good quality. This 

 is Coal No. 7b of our series, and is that worked at Harlem, in Carroll 

 county. There are a few places in the northern partof Jefferson where 

 it is worth working. South of the railroad it is generally but a few 

 inches in thickness, and has no economic value. 



THE LOWER COAL GROUP. 



In all the northern part of the county five workable seams of the 

 Lower Coal Group lie above drainage, and are opened and worked in 

 many places. These are Coal No. 7, locally known as the "Groff Vein" 

 and "Salineville Strip Vein;" Coal No. 6, the "Big Vein;" Coal No. 5, 

 or the "Roger;" Coal No. 4, the " Hammondsville Strip," and Coal No. 3, 

 the "Creek Vein." The latter lies about thirty feet above the Ohio, at 

 the mouth of Yellow Creek, and runs along the river bank at about the 

 same level to Sloan's Station. Here a rapid southerly dip begins, which 

 soon carries all the lower coals beneath the surface. 



Borings and shafts in the northern part of the county have revealed 

 the presence of two, or, sometimes, three thin coal seams within a hun- 

 dred and fifty feet of the "Creek Vein," but, so far as known, these are 

 nowhere of workable thickness. Deeper borings, of which a large num- 

 ber have been made for salt and oil in the northern part of Jefibrson 



members of the GeoJogical Corps. Since it is impossible in this vicinity to obtain a 

 vertical section, the outcrops of the Pittsburgh coal being west of the river, while the 

 shafts are located on the river bank and down a south-easterly dip, the true distance 

 between the two coals has been doubtless somewliat exaggerated. The sections at 

 LaGrange and Eush Knn are, however, so nearly vertical that there is no great liability 

 of error from the cause cited above, and the distance as measured there between the 

 Pittsburgh and shaft coals — a little over 500 feet— is probably about the average for 

 ,this region. 



