clays, their origin, composition and varieties. 67 



5. The Lower Freeport Clay. 



For the clay seam that underlies the Lower Freeport coal, no great 

 development can be asserted and no great peculiarity of composition can 

 be claimed. At one locality, viz., in the vicinity of Moxahala, Perry 

 county, the seam has been found in the condition of a hard or flint clay, 

 but of only moderate excellence. It carries enough oxide of iron to shut 

 it out from the highest grade. Usually the clay is of the ordinary type 

 of the plastic under-clays of the Coal Measures. It is possible that 

 special adaptations will be found in some of its outcrops when the demand 

 from our clay manufactures becomes more extensive. 



6. The Upper Freeport Clay and Shale. 



Much more can be said for the agillaceous deposits of this horizon 

 than for the two last named. They are found in large volume and 

 extend much more widely throughout the Coal Measures than the coal 

 from which they derive their name. At several points in its extent, the 

 Upper Freeport clay has assumed a hard or flinty phase, and then 

 becomes a refractory clay of greater or less excellence. In western Penn- 

 sylvania this phase is known as the Bolivar clay. In the Muskingum 

 Valley, below Zanesville, it has been worked to a small extent, under the 

 name of the Ballou clay. 



The common phase is found to be well adapted to all ordinary uses 

 in almost all parts of the state. It is certain to become one of the main 

 dependencies of the future clay-working industries of those districts in 

 which it occurs. 



The detailed description of the persistent deposits of clay and shale 

 of the state series, will not be carried beyond this point in our review. 

 The Lower Barren Measures that follow the Lower Coal Measures, next 

 in ascending order, contain vast deposits of shale, the true value of which 

 is just beginning to be understood and appreciated. It is the paving 

 brick industry that has, for the first time, shown the possibilities of 

 service that they contain. These shales are distributed through the 

 entire series, but about the middle portion of this division, some deposits 

 of peculiar excellence have been developed, particularly in the Sunday 

 Creek Valley. That part of the series bounded by the Cambridge lime- 

 stone below and the Crinoidal limestone above, seems admirably adapted 

 to paving block manufacture. No true fire-clays are known in this 

 division until its summit is reached in the Pittsburg coaj. A fire-clay of 

 some promise has been noted Underlying this great coal seam at a few 

 points in Athens county. It is not known that any test has been made 

 by which its character or value can be determined. At a single point in 

 eastern Ohio, Viz., at Bellaire, a bed of shale, twenty feet or more in thick- 

 ness directly underlies the Pittsburg coal. This deposit has lately been 

 made the basis of a promising paving block and sewer-pipe plant. 



