THE "RED HILLS" OF CANVEY ISLAND. 141
arrested at the surface. Rain falling on a land surface, and
passing through soil containing sand and clay on descending
to lower levels would carry with it suspended particles, and these
would tend to form bands wherever the subsoil was of a nature
to retard filtration, a condition that is eminently met with at
compacted burnt clay levels.
Operations Carried on at the Canvey Red-Hill Sites.
The conclusions reached by the Exploration Committee have
been referred to. Mr. Chalkley Gould, writing in the Victoria
History of Essex, vol. i., p. 307, regards with favour the view
expressed by Mr. William Cole in 1906, viz., that the Red-hill
mounds are the site of potter's works. If this be so the manufac-
ture of crude red pottery in quantity would demand an adequate
supply of suitable material—a sandy loam or brick-earth
containing a notable proportion of sand. Such material must
then have existed at or near the surface and in the immediate
neighbourhood of the place where it was moulded and fired, as
the excavation from a depth and transport to a distance of the
huge mass of material handled on the Red-hill sites would have
been a lengthy and laborious operation in the age we are con-
sidering. At the Canvey sites, it is true, the clay at the surface
to-day is an alluvium containing only 3 to 4 per cent. of sand, a.
material that by itself would have been quite unsuitable for the
manufacture of bricks or pottery. The old land surface is there
buried underground and is difficult to locate, but loam containing
up to 40 per cent. of sand has been identified at the old working
surface beneath the sites, and exists to-day on the Island locally
near the surface of neighbouring but unworked sites, see Map,
sites A, B, C, D, E, F and G.
On the mainland itself along the estuaries of the Blackwater
and Crouch, where the bulk of the Red-hill mounds are situated,
the geographical environment is favourable to the same suppo-
sition, consisting, as it does, in one area of widespread deposits of
glacial sands, gravels, and derived brick-earths, and in the other
of local deposits of Bagshot Sand that indicate the probability
that suppplies of sandy loam were located at or near the im-
mediate neighbourhood of the Red-hill sites.
A sample of the surface material taken from the side of one of