162
THE ESSEX NATURALIST.
they were criss-cross. In this layer were pockets of midden rubbish,
used for repairs of the road, containing : (a) Bones, mainly broken
for cooking, of red deer, horse, dog, sheep or goat, pig, Bos longifrons
and half of a human mandible, (b) Tools. (c) Shells of edible
molluscs, (d) Pottery of Hallstatt-La Tene I. period.
The upper surface of the causeway was level, 7 ft. above O.D., 51/2 ft.
below T.H.W., and 4 ft. from the surface ; it was subaerial throughout.
The islet road is 6-12 in. and the corduroy road 31/2 ft. thick ; the latter was
partly submerged, resting on the bed of the mere at 31/2 ft. above O.D.
The average water-level of the old mere is 51/3 ft. above O.D. ; this estimate
is based on the distribution of shells of Limnaea pereger (Mull.) and
Planorbis leucostoma (Milii.) in the corduroy road. These freshwater
molluscs were very abundant and are characteristic of permanent water
in shallow sedgy meres ; they were the only aquatic forms found in this
part of the causeway and the only shells below the estimated water-level ;
they were accompanied here by many elytra of freshwater beetles, of dark
purple and vivid green colour ; a few shells occurred just above this level,
the result probably of freshets or winter rains which caused a temporary
rise in the water-level ; with this exception all the shells above the water-
level are terrestrial. The islet road was entirely subaerial ; the shells
are nearly all terrestrial, except for a few varieties of aquatic forms
characteristic of swamps with pools liable to desiccation. The causeway
is black throughout, contrasting with the pale dove-grey colour of the
lacustrine clays on which it rests and the dark-grey or yellowish-grey
colour of the marine clays which cover it.
The surface of the islet road yielded fragments of British gritted ware,
whose forms indicate the influence of Romanization. Here also were
large numbers of shells of Helix aspersa, whole and fractured. Mr. A. S.
Kennard is of opinion that Helix aspersa, a native of the West of England,
was deliberately colonized for food by the Romans ; it appears in the
South-east wherever Roman remains occur. In Southchurch, it may have
been introduced in the Roman period and eaten instead of Helix pomatia,
or of Helix nemoralis, which appear on many prehistoric sites. Sherds
of later Roman pottery have been found on the land site, derived probably
from the Roman pottery kilns at South Shoebury.
The causeway, therefore, was constructed mainly of fascines,
uniformly arranged and supplemented where necessary with
larger timbers ; the materials being collected from the margins
of the mere and stream, the gravel beds and forest. The careful
construction and concerted labour imply an important objective,
and the contents of the pockets suggest an approach to a habita-
tion site in the Eastern Mere. The construction may be assoc-
iated with the West Alpine immigrants who settled in the
Thames Valley in 800-500 B.C. and left their traces in South-
church and its neighbourhood. The pottery of the pockets
shows that it had surface repairs in the Hallstatt-La Tene I.
period, c. 500-300 B.C. This pottery has decoration very similar