ARGILLACEOUS LIMESTONE: CEMENT ROCK. 331 



mill necessitates very heavy blasting, and this prevents permanent 

 tracks and cable ways from being laid near to the working-face. 



At several quarries the loading into the cars or carts is accomplished 

 by means of steam-shovels. The cement rock seems to be well 



FIG. 68. Open cut in cement rock. 



adapted for handling by steam-shovels, but even then much sledging 

 is necessary and the blasting operations are interfered with. 



Cement production of the district. The importance of these Lehigh 

 district cement-rock deposits is well brought out by Table 154. 



Probable extension of the industry. As noted in the earlier portion 

 of this chapter, the cement deposits have been developed only from near 

 Reading, Pa., to a few miles west of Stewarts ville, N. J. Most of the 

 readily accessible cement land between these points has been taken 

 up by the cement companies or is being held at impossible prices by 

 the owners. Under these circumstances it seems probable that few 

 additional plants can be profitably established in the district now 

 developed, and that the growth of the industry here will be .brought 

 about by extending the district. A few notes on the distribution of 

 the same cement-beds in adjoining areas may therefore be of interest 

 to those desiring to engage in the manufacture of Portland cement 

 from materials of the Lehigh district type. 



