The Phosphate Deposits of South Carolina

The deposits of phosphate rock in the vicinity of Charleston, S. C., were among the first discovered in the United States, and until about 20 years ago the field was one of the largest producers in the world. The workable deposits are confined to the region lying in general between Charleston and Beaufort and extending about 25 miles back from the coast. The phosphate rock occurs in a thin bed which underlies irregular areas within the region defined. This bed is commonly less than 18 feet below the surface, and is thus comparatively easy to mine, but, owing to the rather low grade of the rock and the exploitation of richer and more easily accessible deposits in Florida and Tennessee, production in the South Carolina field has now almost ceased. A number of papers describing this field have been published, most of them 20 years or more ago, but in view of the present more extended geologic information concerning this region it has been thought advisable to prepare this account, which is based on a brief field study by the writer. The examination of the field was made in January, 1914. The writer is indebted to Mr. Earle Sloan, formerly State geologist of South Carolina, for many courtesies and for some unpublished information concerning the geology. Mr. John Hertz, who has long been engaged in phosphate mining, kindly contributed several maps and furnished valuable data, and Messrs. William Gaillard, Bachman Smith, and William Alston assisted in many ways. In addition to information privately communicated, several of the earlier reports on the field have been freely drawn upon for pertinent facts. .The earliest report on the phosphate deposits was published in 1868 by N. A. Pratt, 1 and this was followed in 1870 by a more extended account by F. S. Holmes.2 Both of these papers are written in narrative and more or less popular form. In 1870 N. S. Shaler 3 contributed a short scientific description. In 1880 C. U. Shepard, jr., 4