16 
NODULE BEDS. 
being the only mineral industry of any importance connected with 
the Crag, it may be convenient here to give some further particu¬ 
lars relating to the economic value of the deposit. The mode of 
occurrence of the Nodule Bed ” has already been described. Its 
thickness varies considerably, for in many places there are only a 
few scattered lumps of the phosphate at the base of the Red Crag, 
while in others they form a seam as much as 18 inches thick. 
The usual thickness is less, pits seldom showing more than 10 or 
12 inches. In working the Nodule Bed, the method adopted is 
to begin at the outcrop, and work with a long straight face 
toward the rising ground. The overlying Crag is removed in 
successive steps and thrown into the abandoned part of the pit, 
the surface being made good as the work goes on, so that the land 
may be again available for agricultural purposes as soon as 
possible. When a sufficient area of the Crag has been cleared 
away, the lowest portion, which contains the phosphatic nodules, 
is carefully removed and screened, and then hand-picked to get 
rid of the valueless part, such as the flints, quartzite pebbles, 
shells, and box-stones. Though the box-stones are phosphatized, 
they contain apparently too small a per-centage of phosphate of 
lime to be worth taking. In the process of screening all the small 
phospatic nodules are lost, but it is difficult to see ho\v that can 
be avoided. 
It is impossible to obtain trustworthy estimates of the available 
amount of })hosphate, but no very large proportion has yet been 
removed. The depth at which it can be worked profitably varies 
greatly according to local circumstances and the market prices of 
the stone. More than 30 feet of overlying sands are removed at 
Foxhall, but this thickness is quite exceptional, and the working 
depends largely on the present low rate of wages in the district. 
There must be many square miles of the Nodule Bed within 30 
feet of the surface. 
No exact statistics are available as to the amount of phosphate 
raised; but Mr. W. Colchester has kindly supplied the following 
estimates :— 
Tons. 
Tons. 
1847 about 500 
1877 
about 10,000 
1848 „ 
1,000 
1878 
9 y 
10,000 
1849 „ 
3,000 
1879 
yj 
4,000 
1860 „ 
5,000 
1880 
9 9 
5,000 
185] „ 
6,000 
1881 
99 
5,500 
1852 „ 
8,000 
1882 
9 9 
5,500 
1853 „ 
10,000 
1883 
99 
6,500 
1854 „ 
12,000 
1884 
9 9 
7,800 
18551 
Average 
1885 
99 
6,000 
1856 [ 
about 
1886 
9 9 
4,000 
1857 J 
9,000 
1887 
9 9 
2,000 
1858 „ 
10,000 
1888 
9 9 
3,000 
18691 
Average 
1889 
9 9 
5,000 
to [ 
about 
1876 J 
9,000 
