1874.] 199 [Whittlesey. 



above the so-called " Mahoning Sandstone." If I am correct in the 

 profile at Bridge 42, there are four more beds in the lower series 

 below Salineville No. 6, making eleven in all, with a strong probabil- 

 ity that another should be added at Steubenville. If the Creek vein 

 is properly No. 3, No. 1 of the same profile, or the block coal, if it 

 exists so near the centre of the basin, should be found within one 

 hundred and sixty to two hundred feet below the channel of the Ohio. 



It has been assumed that the " Mahoning sandstone " of the Penn- 

 sylvania Reports is a reliable guide rock in Ohio. Its position, ac- 

 cording to Prof. H. D. Rogers (Final Report, pp. 477 and 493), is at 

 the base of the "lower barren measures." On the Ohio side of the 

 State line it has always one seam of coal (No. 7) above it, and at the 

 mouth of Yellow Creek, on the Ohio River, it has two. The furnace 

 coal of Steubenville has not been shown to be identical with the 

 upper seam at Yellow Creek, and if not there are three seams in the 

 " barren measures " ; seams that are not thin and valueless, but of 

 workable coal. From the furnace seam at Steubenville as far as 

 Wheeling, the real barren measures, where the true Mahoning should 

 be, are something over 500' in thickness. 



Comparing the numerous profiles in Ohio with each other, the sand- 

 stone between Nos. 6 and 7 is no more heavy or irregular than three 

 other beds of this rock which are found beneath it, on or near beds 

 Nos. 3, 4 and 5. The profiles show it to be every where a changeable 

 rock, replaced by shale frequently within distances of a mile. This 

 changeable feature of all the beds of the series, is particularly dwelt 

 upon by Prof. Rogers when treating of the country between the 

 Alleghany River and the Ohio line. 



The Mahoning sandstone of the Pennsylvania and Virginia Re- 

 ports belongs to the lower part of the lower barren group. That of 

 Ohio is placed between seams No. 6 and 7, and is often wanting. In 

 some places there is a bed of coal above No. 7, before the barren 

 ground is reached, making every where one, and often two seams of 

 coal in the barren measures, if this classification is correct. 



Between the passage of the Pittsburg seam beneath the hills 

 northwest of the Ohio, and its reappearance in the valley of Wills 

 Creek, between Barnesville and Cambridge, the thickness of the 

 barren measures has contracted from 500 to 140 feet, the seams of 

 coal not being much farther apart from the bottom of the series to 

 the top, than they are in the productive measures. The limestone 

 group overlying the Pittsburg seam, forty to sixty feet thick, has also 



