60 GEOLOGY OP OHIO. 



The elements of interest to us in the present connection are the fol- 

 lowing: Tionesta clay and shale, Upper Mercer clay, Lower Mercer clay, 

 Quakertown clay and shales, Sharon shales. These elements will each 

 be briefly characterized in the order that has been followed thus far in the 

 chapter, viz., the ascending order. 



The lowest coal seam of our series, the true designation of which is 

 the Sharon coal, but which is also known as the Mahoning Valley coal, 

 the Youngstown coal, the Akron coal, the Massillon coal, the Jackson 

 Shaft coal, rests on a thin deposit containing a small amount of clay, 

 which in turn is supported by the massive Sharon conglomerate. No one 

 would venture to call this particular underclay as it generally appears, a 

 fire-clay. It is highly silicious and would serve as refractory material of 

 fine grade. It resembles in composition and character the gannister of 

 the English miner. No use has thus far been made of it in Ohio and it 

 is not therefore included in the list of our clay resources. 



(a) The Sharon Shales. — This series directly overlies the Sharon 

 coal in most sections. In thickness it ranges from one to fifty "feet. In 

 its most characteristic form it is a dark blue, sometimes an almost black 

 shale, carrying at certain levels heavy nodules of iron ore, which in the 

 early days of iron manufacture in western Pennsylvania and northeastern 

 Ohio were drawn upon to a small extent for furnace supplies ; but they 

 are not likely to be further molested. Near the bottom of the series and 

 overlying the coal, the shale frequently contains abundant and charac- 

 teristic fossil plants. The shales proper have lately become the basis of 

 one of the largest sewer pipe industries of the Un ted States, at Akron and 

 in its immediate neighborhood. The same deposit is also worked in Ak- 

 ron in one of the largest roofing tile works of the country. The shale is 

 generally high in iron oxide,, the amount of this substance ranging be- 

 tween 10 and 15 per cent. So important a proportion of iron as this in a 

 clay would be sure to impress a particular character on all the products 

 manufactured from it. The excellent color of the Akron sewer pipe, 

 which has done so much to. commend it in the general markets of the 

 country, is mainly due to the abundance of this element. 



(b) The Quakertown Clay and Shale. The deposits here named 

 occupy a few feet (5 to 30) between the two divisions of the Massillon 

 sandstone, when such a division occurs. They can, with a great deal of 

 propriety, be referred to the Quakertown coal, from which they take their 

 name, one body of the clay lying under and one directly over the carbon- 

 aceous streak that is the sole representative of this coal seam in a large 

 part of the area where it is due. The argillaceous depdsits of this age 

 are worked in but three counties of the state at the present time, so iar as 

 known, viz., Summit, Portage and Stark counties. In Summit they fur- 

 nish the stock for the important potteries of Springfield, and in Portage 

 for the Mogadore potteries. The Massillon Fire Brick Company has de- 

 veloped the most valuable deposit yet known on this horizon and so far 



