50 



The Phosphates of America. 



large number of pits under our direction, is represented in the fol- 

 lowing table, the figures being averages compiled from our field 

 not e-book : 



This is still further illustrated and will be probably more clearly 

 conveyed by the accompanying sketches of typical sections, pre- 

 pared by R. A. F. Penrose, Esq., and borrowed from Bulletin No. 

 46 of the United States Geological Survey. 



Section ENE. and WSW. through Pinckney's phosphate field. South Carolina. A, 

 sand ; B, ferruginous sand ; C, phosphate rock ; D, Ashley marl. Scale : 1 inch = 60 feet. 



So far as we have been able to discover, no systematic inves- 

 tigation has been made of those lands which contain the phosphate 





Average section in Pinckney's phosphate mine, Berkeley County, South Carolina. A, clay 

 sand ; B, ferruginous sand ; C, phosphate rock ; D, Ashley marl. Scale : 1 inch = 6 feet. 



deposit at a greater maximum depth than 15 feet, it having been 

 hitherto considered impracticable, under the conditions of abun- 



