ARGILLACEOUS LIMESTONE: CEMENT ROCK. 



333 



diate vicinity of that fortunate area. As noted in the last chapter, 

 cement rock exactly similar to that used in the Lehigh district occurs 

 in other parts of Pennsylvania, in Maryland, and the Virginias. Similar 

 clayey limestones occur southward, along the Appalachian Valley, 

 through Tennessee and northern Georgia. In all this range, however, 

 they have never been used as Portland-cement materials, though a 

 natural-cement plant was erected a few years ago at Rossville, Ga., a 

 few miles south of Chattanooga, to utilize limestones closely similar to 

 the Lehigh rock in composition. 



The following analyses show the composition of "cement rocks" 

 used at various Portland-cement plants in the Western States, together 

 with that of the purer limestones used for mixing. 



TABLE 155. 

 ANALYSES OF "CEMENT-ROCK" MATERIALS FROM THE WESTERN UNITED STATES. 



In addition to the "cement rocks" noted in this chapter, it is neces- 

 sary to call atention to the fact that many of the chalky limestones 

 discussed in the following chapter are sufficiently argillaceous to be 

 classed as "cement rocks". Because of their softness, however, all 

 these chalky limestones will be described together. 



List of references on " cement rock ". 



Bassler, P. S. Cement materials of the Valley of Virginia. Bulletin 260, 

 U. S. Geol. Survey, pp. 531-544. 1905. 



Catlett, C. Cement resources of the Valley of Virginia. Bulletin 225, 

 U. S. Geol. Survey, pp. 457-461. 1904. 



Eckel, E. C. Cement-rock deposits of the Lehigh district of Pennsylvania and 

 New Jersey. Bulletin 225, U. S. Geol. Survey, pp. 448-456. 1904. 



Eckel, E. C. Cement materials and cement industries of the United States. 

 Bulletin 243, U. S. Geol. Survey, pp. . 1905. 



Kiimmel, H. B. Report on the Portland-cement industry in New Jersey. 

 Ann. Rep. N. J. State Geologist for 1900, pp. 9-101. 



Peck, F. B. The cement-belt of Lehigh and Northampton counties, Pennsyl- 

 vania. Mines and Minerals, vol. 25, pp. 53-57. 1904. 



