12 
NODULE BEDS. 
of the district do they occur in sufficient abundance and sufficiently 
near the surface to be worth working. It is consequently only 
from a limited number of localities that the older fossils, vvith 
which we are especially concerned in this Chapter, have been 
obtained. A triangular area enclosed within a line drawn from 
Ipswich to the sea at Orford, and another to the Stour at Dover- 
court, will include the whole of the district over which phosphate 
has been dug. As the sections of the Nodule Bed will be de¬ 
scribed with the Bed Crag, it is unnecessary here to enter into 
details respecting them; it will be sufficient to mention that box- 
stones are especially abundant around Trimley, between the 
Kivers Orwell and Deben. 
The materials included in the Nodule Bed may be classed 
under several heads. First we have the rocks and fossils 
belonging to periods older than the Tertiary. These are:— 
Granite and igneous rocks. 
Jurassic rocks and fossils. 
Cretaceous fossils, large flints, Lower Greensand chert. 
The next group includes undoubted Eocene fossils : — 
Mollusca, many species 
Crustacea, many species 
Teeth of Lamna and Otodus 
Coryphodon 
Hyracotherium 
Septarian nodules 
|>from the London. Clay. 
J 
Then come a number of Upper Tertiary vertebrate remains, 
perhaps belonging to more than one period, and the box-stones. 
It is with this last group that we have now more especially to 
deal. 
So many difficulties stand in the way of the separation of the 
various phosphatized bones into groups according to their 
geological age, that it will be advisable to deal first with the 
mollusca contained in the box-stones. The box-stones are rounded 
fragments of a peculiar brown sandstone, easily recognizable, and 
belonging, with little doubt, to a single horizon. The sand varies 
in fineness, but is usually somewhat coarse, many o£ the lumps 
containing small quartz pebbles; in fact it is just such a bed 
as might from its disintegration yield the coarse sand of the 
Bed Crag. The cementing material is largely calcareous, but 
Mr. Teall, who has tested two samples, states that they are both 
also highly phosphatized, though from the quantity of sand 
contained in them they may be too poor to be worth working. 
Shells are abundant, but generally occur in the state of hoUow 
moulds, the shell itself having been entirely removed by percolating 
water. These casts—as is the case in the Lenham ironstone—are 
often so sharp and well-defined that there is no difficulty in 
determining the species. Sometimes, however, the moulds have 
been subsequently filled with crystals of quartz, oxide of iron, or 
