6(J DEPOSITS OF PHOSPHATE OF LIME. Ibull.4& 
VII. Argillaceous or arenaceous marls, containing 7 to 10 per cent, of phosphates. 
B. River deposits: 
Beneath the river deposits occur either — 
I. A gray marl, sometimes in nodules resembling phosphate, with 5 per cent, of 
phosphates, underlaid by 
II. A white, hard marl inclosing phosphate grains and containing 3 feo 5 per cent, of 
phosphates (Wando River) ; or 
I. A green sand with some clay and rich in black phosphatic grains, occurring with 
the phosphatic rock and beneath it, containing 15 per cent, of phosphates. 
II. Soft and hard marls several feet in thickness, and containing 10 to 15 per cent, 
of phosphates (Stono River) ; or 
I. Hard marls. Poor in phosphates (-£ to 1 per cent.) unless their tops be coated 
with phosphate rock (Coosaw River). 1 
It is difficult to calculate the yield of river nodules per acre, as the 
currents have heaped them up in some places and carried them away 
from others. 
As will be seen from the accompanying map by Dr. C. U. Shepard, jr. 
(PI. I), there are three principal localities in the phosphate region where 
active mining operations are now carried on. It is not, however, all 
over these areas, but only in certain parts of them, that the nodules 
are found. Nor are they the only places in South Carolina where phos- 
phates occur, but they are the districts where they are found at a depth 
beneath the superficial deposits not too great to permit profitable min- 
ing. 1 The first of these regions lies north and east of Charleston and 
stretches from tile Wando River and the eastern branch of the Cooper 
River on the northeast to Rantowles Creek and Stono River on the 
southwest. In this area are some of the largest phosphate diggings in 
South Carolina, including as it does the Bradley, Charleston Mining and 
Manufacturing, the Magnolia, Bolton, and Black and Williams's mines. 
There also are the river deposits in the W r ando, Stono, and Cooper Rivers. 
Large quantities of small nodules of excellent quality have been obtained 
from the bed of the upper part of the Wando River. Phosphate of good 
quality has also been gotten from the bed of Stono River, but the de- 
posit forms in some places such a solid floor on the river bottom that 
mining operations at the present low price of phosphate would be un- 
profitable. Mainly on account of their inaccessibility the deposits in 
the eastern branch of the Cooper have not been much worked. 
The second of the three principal phosphate districts is due west of 
the locality last described and extends from the Edisto River on the 
east to Horseshoe Creek on the west, including the river deposits in 
these two streams. The phosphate found in this region is of excellent 
quality, but does not occur in a continuous bed or at a constant depth. 
Consequently it can be profitably mined in few places. It occurs largely 
in pockets and patches on the underlying bed. 
The third locality where phosphate exists at a conveniently accessible 
depth extends with intervals from the Bull to the Broad Rivers, and 
x Dr. C. U. Shepard, jr. : South Carolina Phosphates. 
(540) 
