72 DEPOSITS OF PHOSPHATE OF LIME. [bull. 46. 
phatization of the surface of a bed of sandy marl. The phosphate, 
having a tendency to segregate, formed in some places richer than in 
others. Then, when the bed was exposed to erosion, only the parts 
which were strongly enough cemented together survived. Often, around 
the siliceous pebbles in a nodule, concentric bands of phosphate of lime 
may be observed, showing its strong tendency to form in segregations. 
These deposits have not as yet been put to any commercial use. 
They are of a low grade, averaging only about 45 per cent, phosphate 
of lime, and occur only in small patches of from one to twelve acres. 
(2) The second variety of phosphate deposits found in North Carolina 
belongs to the class of phosphatic conglomerates. They are found in New 
Hanover and Pender Counties and consist of a mass of Tertiary shark 
teeth, bones, nodules, and quartz pebbles, all well rolled and rounded 
and cemented together, along with grains of greensand, in a calcareous 
matrix. At Castle Hayne, New Hanover County, they occur in a bed 
sometimes over six feet deep. The largest pebbles and nodules are 
nearest the top of the formation and never exceed the size of a horse- 
chestnut. They grow smaller with the depth, and at six feet they are 
not larger than an apple seed. The character of the whole mass of the 
deposit also varies very much with the depth. The top of the bed is a 
hard and solid rock, but at two feet it begins to get softer, and at three 
to four feet the conglomerate bed is simply a mass of loose, calcareous 
marl containing pebbles. The section below, from near Castle Hayne, 
N. C, will show the nature of this bed. • 
1. White sand to 3 feet. 
2. Brown to red, ferruginous, sandy clay or clayey sand, 1 to 3 feet. 
3. Green clay, 6 to 12 inches. 
4. Dark-brown, indurated peat, 3 to 12 inches. 
5. White, calcareous marl, to 2 feet. 
6. White shell rock, to 14 inches. 
7. Phosphatic conglomerate rock, 1 to 3 feet. 
8. Gray marl containing smaller nodules than the overlying bed, 2| to <\% feet. 
9. Light colored, calcareous marl, containing nodules which are smaller than those 
in the overlying beds and which grow fewer and smaller at a depth. Many shells. 
The line between the shell rock (6) and the conglomerate bed (7) is 
very sharply drawn. There are occasionally a few nodules found in the 
shell rock near the line of contact, which may have been derived from 
the conglomerate. The surfaces of all the beds are very uneven, espe- 
cially that of the calcareous marl in the above section, which occurs only 
in patches on top of the shell rock (Fig. 30). 
Near Wilmington, N. C, the following section was obtained: 
1. Sandy soil, 2 feet. 
2. Greensand bearing a few phosphatic nodules about the size of a pea, 4 feet. 
3. Gray marl, 6 feet. 
4. Limestone rock bearing a variable amount of nodules, of the same size as near 
Castle Hayne. 
The nodules in 4 sometimes make up as much as three-fourths of 
the contents of the bed; at others they occur scatteringly through the 
(546) 
