GEOLOGY. 24' 



THE NODULAR PHOSPHATES OF SOUTH CAROLINA. 



The belt of nodular phosphates appears to extend, more or less 

 interrupted, from the Wando and Cooper Rivers, some 15 to 30 

 miles above Charleston, in a south-south-westerly direction, par- 

 allel to the coast line, as far as St. Helena Sound and Bluti"ton, 

 near Port Royal. As yet the precise area is unknown ; no ac- 

 curate survey having been made, although this want is daily felt 

 by the community. It would be erroneous to suppose that there 

 is a well-defined stratum of any such extent as this area above 

 mentioned. On the contrary, the bed appears only in patches, 

 some of which, however, are many miles in diameter. On the 

 Wando and Cooper Rivers the nodules are found in compara- 

 tively small beds, generally but a few inches in thickness ; still, 

 limited deposits, one to three feet thick, have been deposited in 

 some localities of this neighborhood. On the peninsula between 

 the Cooper and Ashley Rivers the deposit assumes the form of a 

 well-defined stratum, in many places attaining a thickness of 18 to 

 24 inches, and underlying hundreds of acres, at an average depth 

 of about 3 feet from the surface. The nodules vaiy in size from 

 that of a walnut to masses weighing 200 pounds and over ; they 

 lie compactly together with but little marl between them. This 

 marl is composed of 30 to 60 per cent, carbonate of lime, a few 

 per cent, phosphates of iron, lime, and alumina, the balance being 

 chiefly sand and peroxide of iron. At other points on the penin- 

 sula the nodules rarely exceed a few pounds in weight, and are 

 sparsely distributed. The favorable localities lie east of Goose 

 Creek, near the Cooper River. The Ashley beds were the first 

 discovered, are the best known, largest in extent,, and most 

 mined. This deposit extends, at an accessible depth, over, per- 

 haps, 1,000 acres, on both sides of the river, and running back 

 from it ibr several miles in some places. The beds are quite accessi- 

 ble, not only on account of the depth of Ashley River and their 

 proximity to Charleston, but because of their lying close to the 

 surface (generally within two feet), in a light soil, which sepa- 

 rates easily from the nodules on handling or washing. The nod- 

 ules are of a yellowish-gray color, of less specific gravity than 

 those elsewhere found, their surface but slightly irregular, and 

 their composition tolerably uniform. The best beds lie on the 

 river 10 to 20 miles from Charleston ; further up stream the nod- 

 ules are found in a sandy soil, and become permeated with sand 

 to the amount of 30 per cent, and over, when the phosphates do 

 not reach 50 per cent. On some plantations the bed of phosphatic 

 nodules is over two feet in thickness ; and the amount of marl^et- 

 able material produced from mining an acre may exceed 1,200 

 tons. On the Stono and Edisto Rivers there have been found but 

 few rich deposits, the stratum exhibiting continuity in but occa- 

 sional spots. As a rule, tiie nodules lie deeper on these rivers 

 than on the Ashley. Heavy deposits have been discovered on the 

 flats in the neighborhood of St. Helena Sound, covering vast sur- 

 faces at little depth from the surface, occasionally forming a com- 



