208 



CEMENTS, LIMES, AND PLASTERS. 



of which affords an admirable floor for the galleries. For about 18 

 inches at the bottom the dark cement rock is too sandy for use. With 

 this exception and a few small layers of chert it is all available. At 

 Whiteport the upper bed is 12 feet thick and the lower 18 feet, while 

 they are separated by 17 to 20 feet of limestone. 



TABLE 93. 

 ANALYSES OP NATURAL-CEMENT ROCK, ROSENDALE DISTRICT, N. Y. 



1. Lawrenceville. J. O. Hargrove, analyst. Letter to writer, Oct. 4, 1900. 



2. Rondout. L. C. Beck, analyst. "Mineralogy of N. Y.", p. 78. 



3. Lawrenceville. J. O. Hargrove, analyst. Letter to writer, Oct. 4, 1900. 



6. " Rosendale district. C. Richardson, analyst. Brickbuilder, vol. 6, p. 151. 

 July, 1897. 



7. Lawrenceville. J O. Hargrove, analyst. Letter to writer, Oct. 4, 1900. 



8. Average of preceding seven analyses. 



Northward and northwestward from the Rosendale-Rondout dis- 

 trict no natural-cement plants are to be found until Schoharie County 

 is reached. Here, at Howe's Cave, a single plant has long been engaged 

 in the manufacture of cement from a 7-foot bed of rock. 



TABLE 94. 

 ANALYSES OF NATURAL-CEMENT ROCK, SCHOHARIE COUNTY, N. Y. 



1. Bottom of cement-bed, Howe's Cave. C. O. Schaeffer, analyst. 18th Ann. Rept. N. Y. State 



Geologist. D. 69. 



C. O. Schaeffer, analyst. 18th Ann. Rept. N. Y. State 



,.., n. 69. 



3. Howe's Cave. 



Geologist, p. 69. 



L. C. Beck, analyst. "Mineralogy of New York", p. 79. 



