Fig. 28 is a careful sketch of part of the Cyrena-bed, by Mr. S.
Skertchly. The section is as follows, in ascending order:—sands 4 feet,
wavy laminated brick-earth beds 6 feet, brick-earth 5 feet, a bed of
pebbles from the Woolwich series, brick-earth, and clay 6 feet;
the Cyrena sand-bed, C, passing upwards into laminated brick-
earth, gravel, and loam, 25 feet thick.
Fig. 29 is a section of the most fossiliferous part of the Crayford pit.
Fig. 29.—Section in Crayford Pit.
along the line K L (see P1. VI.). It represents about 30 feet in height
by 150 in length; so that the horizontal scale is about five times the
vertical. It is intended to show the variation in the pebble-beds, C,
and the thickening of the whole series in the direction of the escarpment. The pebble-beds, C, are in three divisions, and the great Cyrena-bed, D, rests on one of them; but shells are found in B, C, D, and
E, though not in the covering bed F, which contains flint-pebbles
distributed through it in the usual manner. The lowest beds are
not seen in fig. 29; but at X, near M N, there are several openings
at a depth of 35 feet from the surface, where a bed of coarse gravel
is visible, which is near the eroded surface of the chalk. The
chalk itself, with a covering of gravel or sand, is seen in the ponds
marked P in the Crayford pit, where the Water stands a little below
the level of high water.
