Bracklesham sands.—Layers of black flint pebbles, in yellow sand. Pipeclays and sands of many colours, enclosing several beds of lignite. 543 feet.
Bognor beds.—Coloured sands of many tints. 321 feet. Dark blue clay, with green earth and shelly nodules. 200 feet
Plastic clay and sands.—Clay, red, &c., between layers of yellow sand. 100 feet.
In the basin of London, the series is less complete.
Mr. Prestwich has determined the place of the London
clay in the series to be below the Bagshot sand, and on
the parallel of the Bognor beds. (GeoL Proc. 1847.)
Hence the following general section:—
Bagshot sands.
London clay, of a dull grey, or blue, or brown, sometimes red; often full of green grains. Septaria abound in certain parts: the rocks of Bognor and Selsea are supposed to belong to the lower part of it. 350 feet.
Sand of various colours, with occasional beds of lignite or plants.
Sand, and layers of clay, with or without shells.
Sand, green and ferruginous, accompanied by flint pebbles, oyster shells, &c.
In Essex, Suffolk, and Norfolk, the plastic clay group
is chiefly represented by the lower green sandy portions,
which appear seldom deficient (being found in the Isle
of Wight, at Reading, Woolwich, Sudbury, &c). The
London clay is seen at Harwich; and a superior marine
deposit, the " Crag, " unknown elsewhere in England,
appears at Ramsholt, Orford, &c. in two divisions,
while a third is added above in the vicinity of Norwich.
Thus we have:—
Upper, or mammaliferous crag; rich in remains of pachydermata, &c., and containing littoral shells.
Middle, or red crag; resembles a raised sea-beach, being composed of layers of sand and pebbles, mixed with marine shells and polypifers, worn fish teeth and bones, cetacean bones, &c., the whole generally ochraceous.
Lower or coralline crag, less ochraceous, almost without pebbles; containing abundance of shells not at all
