THE NONMETALLIC MINEBALS. 365 



contain Tertiary shells (Specimens Nos. 44244 and 34318, U.S.N.M.). 

 The second or conglomerate variety occurs mainly in New Hanover 

 and Fender counties, the beds in some instances being 6 feet in thick- 

 ness, though usually much less. The following section, taken like 

 those above from Dr. Penrose's Bulletin, shows their position and asso- 

 ciation as displayed at Castle Hayne, New Hanover County. 



(1) AVhite sand, to 3 feet. 



(2) Brown and red ferruginous sandy clay, or clayey sand, 1 to 3 feet. 



(3) Green clay, 6 to 12 inches. 



(4) Dark brown indurated peat, 3 to 12 inches. 



(5) White calcareous marl, to 2 feet. 



(6) White shell rock, to 14 inches. 



(7) Phosphatic conglomerate, 1 to 3 feet. 



(8) Gray marl containing smaller nodules than the overlying beds, 2 to 4 feet. 



(9) Light-colored, calcareous marl, containing nodules which are smaller than 

 those in the overlying beds, which grow fewer and smaller at a depth. Many shells. 



The phosphatic nodules in this conglomerate are kidney and egg 

 shaped as sometimes make up as much as three-fourths the contents of 

 abed; usually, however, the proportion is smaller, and .sometimes there 

 are none at all. The mass as a whole does not contain more than 10 

 to 20 per cent phosphate of lime, but it is said to have been successfully 

 used as a fertilizer. The individual may be richer in phosphatic mat- 

 ter on the outer surface than toward the center. 



Aside from the phosphatic layer as described above, phosphatic 

 nodules are found in large quantities in the beds of rivers of these 

 districts, where they have accumulated through the washing action of 

 flowing water, the finer sand clay and gravel having been carried away. 

 Such phosphates naturally do not differ materially from those on land 

 except that they are darker in color and sometimes more siliceous. 



The deposits of South Carolina, though of low grade compared with 

 some others, are now more generally used than any other known phos- 

 phate. The output of the mines, which is yearly increasing, is shipped 

 to the North, South, and East by sea and to the West by rail. This 

 popularity is due not only to the cheapness of the phosphate ($5 to 

 $6 a ton in 1886), but to the many good qualities of the low-grade 

 acid phosphate made from it. The fact that the nodule bed extends, 

 at an accessible depth, over many miles of country, the easy approach 

 for large vessels up to the very mines, the abundance of water, fuel, 

 and labor, and a climate that permits mining operations to be carried 

 on throughout the whole year, all combine to make the South Carolina 

 phosphates the cheapest and consequently the most productive source 

 of supply of this material. Specimens Nos. 34317 and 34318, 34321 to 

 34324, and 34326 to 34328, U.S.N.M. are characteristic. 



Phosphates in the form of nodules and phosphatic marls and green- 

 sands occur in Alabama in both the Tertiary and Cretaceous forma- 

 tions. Their geographical distribution is therefore limited to areas 



