THE CAKBONIFEBOTJS SYSTEM. 155 



THE BARREN COAL MEASURES. 



By the Pennsylvania geologists the term Barren Measures was given 

 to the strata lying between the Mahoning sandstone and the Pittsburgh 

 coal, in western Pennsylvania. These consist of alternations of sand- 

 stone, shale, and limestone, to the thickness of about 400 to 500 feet. For 

 the most part this series consists of shales which are peculiarly high- 

 colored, being often bright yellow, red or blue, or red and yellow mottled. 

 These constitute a peculiar feature in the geological column, and one 

 which serves to identify the horizon at a glance, as no such shales are 

 found above or below. With these are interstratified numerous layers 

 of nodular, frequently ferruginous, limestone. Here and there streaks 

 of coal run through the strata, but they rarely become of workable thick- 

 ness ; and this is emphatically, as its name indicates, barren ground. At 

 the summit of this series lies the Pittsburgh limestone, and above this 

 the great Pittsburgh coal seam (Coal No. 8, or H), the first and lowest of 

 the upper coals. 



Coming westward into Ohio, we find the Barren Coal Measures holding 

 for a long distance almost precisely the character I have described. They 

 are found to contain, however, in Columbiana county, even at the Penn- 

 sylvania line, a workable seam of coal, our No. 7, above the place of the 

 Mahoning sandstone. This may be the representative of the Elk Lick 

 coal of Pennsylvania, or, as likely, a new element introduced into the 

 series. In either case it is so continuous and important a coal seam, 

 and is so closely associated with our group of lower coals, that I have 

 classed it with them. Near Steubenville, however, we find the Barren 

 Measures as completely barren as they are in Pennsylvania. Coal No. 7 has 

 there run out, and throughout the entire interval of 502 to 564 feet between 

 Coal No. 6 — the Steubenville shaft coal — and the Pittsburgh seam, which 

 crowns the hills in the vicinity, no coal of workable thickness is found. 

 Just at this point the Barren Measures are mostly shales, but on the oppo- 

 site side of the river, and on the Virginia side of the Ohio for some miles 



above, they are replaced by heavy beds of sandstone.* 



f 



* I may here remark in passing that this region was peculiar for the formation of 

 sandstones almost throughout the Coal Measures, as will be seen by reference to the 

 sections given by Mr. Briggs in the annual report of the? Geological Survey of Vir- 

 ginia, under Prof. William B. Bogers. From these we learn that at New Cumberland, 

 below Coal No. 7, sandstones fill nearly the entire space and cut all other coals to 

 Coal No. 3, while on the opposite side of the river, a little above, this interval is 

 filled for the most part with shales, and contains three workable seams of coal. A 

 little further down the river, in Vineyard Hill, opposite Steubenville, which lies 

 entirely above the place of Coal No. 7, that coal is cut out, and the Barren Measures 

 are composed mostly of sandstone, as remarked above. 



