2 BULLETIN 18, U. S. DEPARTMENT OF AGRICULTURE. 
no determination other than that of their lime content was made. 
Holmes, 1 in 1844, described " a remarkable bed of nodules or conglom- 
erates 12 inches thick bedded in clay which overlaid the heavy beds 
of marl." 
Tuomey, 2 who succeeded Rufhn, issued a report in 1848 in which 
lie described the same stratum and called the phosphate nodules 
"marl stones." He was convinced that they were derived from the 
underlying marl, for he says, "There is little more left than the silica 
and alumina of the marl." In the appendix of this same report 3 are 
a number of analyses made by Prof. Charles U. Shepard showing the 
phosphate content of the marl, but none showing the amount of phos- 
phoric acid in the nodules. Holmes, 4 in a later publication, also 
regards the phosphate nodules as silicified fragments of the underlying 
marl. 
Chazal 5 states that Prof. Charles U. Shepard was the first to point 
out the true value of the phosphate nodules. He quotes from a lec- 
ture delivered by Shepard before the medical society in 1859, which 
indicates that the latter was then acquainted with the nature of the 
phosphate stratum. Chazal also quotes from letters which show that 
-Shepard had advised the use of the Ashley phosphates in lieu of bones 
as far back as 1860. The outbreak of the Civil War, however, put a 
stop to fertilizer operations, and it was not until 1867 that Dr. St. 
Julien Ravanel, Dr. F. S. Holmes, and Dr. N. A. Pratt revived inter- 
est in these deposits and obtained capital sufficient for their exploita- 
tion. To Dr. Pratt belongs the credit of the first recorded analysis 
of high-grade South Carolina phosphate. 
From 1868, when 12,262 tons of rock were produced from the South 
Carolina fields, to the year 1893, which showed a production of 
618,569 tons, the industry steadily grew, but since the latter date the 
production has diminished, till in 1911 the total amount mined was 
only 169,156 tons. 
GEOGRAPHY AND TOPOGRAPHY. 
The phosphate area of South Carolina lies along the coast in a belt, 
which is in places fully 20 miles wide, extending from the Wando River 
in Charleston County to the Broad River in Beaufort County. (See 
fig. 1.) The coast region as a whole is very little above tide level 
and is intersected with numerous creeks, rivers, and arms of the sea. 
Most of these streams are navigable and afford the phosphate oper- 
ators a ready means of transportation for their product. Many of 
> South Carolina Agriculturist (1844). 
2 Geology of South Carolina, p. 165 (1848). 
s Geology of South Carolina. Appendix (1848). 
i Post Pliocene Fossils of South Carolina. Introduction, p. n (I860). 
5 A Sketch of the South Carolina Phosphate Industry (1904 . 
