606 CLAY, ROAD MATERIALS, ETC. 



in both counties, and as nearly all of these shales are of ma- 

 terial that can be made into brick of some sort it would be 

 possible for each magisterial district to have its own plants 

 for manufacturing its own building material both for residence 

 and paving purposes. A plant of this sort, operated with con- 

 vict labor, under the present state law, would reduce by about 

 one-half the cost of brick for road making. For paving pur- 

 poses the red shales of the Conemaugh Series, described in 

 detail in Chapter VII, will be found best suited. The outcrop 

 of this Series is shown on Map II, and the position of any 

 shale horizon may be easily determined by referring to the 

 general section at the beginning of the Chapter. The Clarks- 

 burg and Pittsburgh Red Shales would probably make a good 

 grade of roofing tile as well as good brick. 



Fire Clay. 



The surface rocks of Lewis and Gilmer, so far as observed, 

 do not carry fire clay of commercial thickness and purity. No 

 flint clay of any kind was found, and no plastic clay of any 

 consequence. 



ROAD MATERIAL. 



River and Creek Gravel. 



Attention has been called in many previous Reports of 

 the Survey to the fact that most of the rivers and creeks of 

 the State contain an abundant supply of gravel, which, being 

 the more resistant portions of the rocks from which they came, 

 afford good material for improving roads that is often cheaper 

 than any other that can be secured. The roads often follow 

 the streams closely, making it possible to macadamize with 

 gravel at much less cost than with stone quarried from the 

 hills. 



Limestone. 



The only calcareous stratum of importance cropping in 

 the two counties is the Redstone Limestone of the Monon- 

 gahela Series, which is found usually only a few feet above 



