HO NORTH-CAROLINA GEOLOGICAL SURVEY. 



the marl bed owned by Col. Clark, three miles above Taw- 

 boro , on the Tar river. It consists of: 



Peroxide of iron and alumina, 6.80 



Carbonate of lime, 16.10 



Magnesia, 0.436 



Potash, 0.616 



Soda, 1.988 



Sulphuric acid, 0.200 



Soluble silica, 0.440 



Chlorine, 0.030 



Phosphoric acid, 0.200 



Sand, . . . 72.600 



Of one hundred parts, only about twenty-six can be re 

 garded as available matter, and yet good results have at 

 tended its use. 



Immediately above the shell marl of the Tar there is a bed 

 of clay some four feet thick. This clay I have submitted to 

 analysis for the purpose of ascertaining the quantity of potash 

 it contains. The results show, however, that as a fertilizer, 

 it is of no importance. It gave me : 



Sand, 84.00 



Peroxide of iron and alumina, 4.40 



Lime, 0.35 



Magnesia, 0.10 



Potash, 0.05 



Soda, 0.02 



Soluble silica, 0.20 



Organic matter and water, 10.50 



99.62 



All the beds except the upper beds of sand were submitted 

 to analysis. Only two in this bank are valuable fertilizers, 

 the shell marl and the upper bed of green sand ; both con 

 tain potash, soda and phosphoric acid ; and there is no neces 

 sity for rejecting the latter when hauling marl for the plan 

 tation. If some method could be devised by which the sand 

 could be cheaply separated from the mass, the remainder 

 would form a marl superior to the richest green sand ; the 



