AN ESSEX FOSSIL ZIPHOID WHALE
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of eastern Essex were fluviatile, constituting remnants of the 100
foot Boyne terrace of the Thames Valley and the lower beds of
the 50 foot Taplow terrace. The river terrace gravels often have
quantities of the flint artifacts of prehistoric men when the bones
of the animals they hunted have failed to survive.
At the present time N.E. Essex is a conspicuously flat plateau
with a maximum elevation of about 125 feet with very shallow
valleys. The latter fact seems to be due to the high level of the
Basement Bed of the Red Crag which in the vicinity of Wix is at
100 feet O.D., whereas in Suffolk it is sometimes near sea level and
the deeper valleys are primarily due to the action of strong springs
from the base of the Crag where it lies on the impervious London
Clay. The Plateau Gravels have been recorded as glacial outwash,
presumably of the penultimate (Gipping) glaciation but little or
no work seems to have been done on them; this may be due to the
rarity of large dry pits.
Figure 4. North-east Essex with sites mentioned in the text.
Work on the anti-aircraft gun site at Mistley Heath during the
1939-45 war resulted in the discovery of elephant and rhinoceros
remains in brickearth which was subsequently seen also at Wix
Lodge. This hitherto unknown mammaliferous deposit can only
be compared with the famous plateau site at Hoxne in Suffolk
which is the Type site for the Hoxnian (Great) Interglacial, in
which the Clacton and Swanscombe deposits are included.
At Hoxne the lake beds are situated at plateau level with a
new valley subsequently formed on each side. This site was first