146 THE ESSEX NATURALIST.
Working in the manner described, the labour of excavation
and transport of raw material would be reduced to a minimum,
waste material would be effectively disposed of, and the whole
mass of raw material on the site exposed for utilization. The
results obtained at selected holes are set out diagrammatically in
the table.
The burnt earth from the Canvey sites is of loose structure
and low density; the sandy loam from which it was presumably
derived has a sp. gr. 40 to 50 per cent. greater than that of the
burnt earth itself. The volume of material on any site where
the tired pots were retained for use must, on this supposition,
have increased in bulk by at least 45 per cent, and this would
account for the low mounds to which the name of "Red-Hills"
has been given, quite apart from the introduction of raw material
from outside.
The question now arises, how far are the operations carried
on at the Canvey sites comparable with those attributed to the
mainland sites, judged from the geographical environment and
the character of the subsoil and associated objects.
In their geographical situation and general character, no
doubt, there is close agreement between the Island and mainland
Red-hills, but close examination in detail reveals significant
differences. In the first place the Canvey sites, unlike those of
the mainland, appear to have all been occupied sites, and the
undoubted occupation that occurred during the Romano-
British period may have been repeated in mediaeval times. In
the second place the absence of saggars, butting pieces and fire
bars on the Canvey sites and the remains in quantity of a lighter
type of crude ware indicates that the industrial operations there
carried on, were not of precisely the same character as those on
the mainland. These various points are illustrated by the
results summarised below:—
7 Excluding Site D°, that of the Romano-British Waste tip.