14 THE ESSEX NATURALIST
lected. For the moment, therefore, no detailed correlation by
terraces and biotas between Aveley, Trafalgar Square and Ilford
is possible. In their paper on the Ilford site West, Lambert &
Sparks (1964, 187) offered no correlation, on the grounds that
much further Stratigraphical work is needed to interpret the
terraces of the Thames Valley. It is hoped that some of these
sites and terraces may be correlated in a projected paper by
Dr A. J. Sutcliffe and Mr J. N. Carreck.
Summary. The deposits containing the elephants at Aveley
appear to have been laid down in a silted-up marsh or river
channel, probably of the Thames. The molluscan fauna shows
similarities to the Ilford, Ipswich and Trafalgar Square faunas,
and in spite of minor differences the molluscs from all four
sites do not show criteria permitting stratigraphic separation.
From Table 1, it will be seen that the molluscs are most abundant
in the middle part of the sequence, especially in H1 and H2, de-
creasing in numbers until there is another increase in B2 and
B2/C matrix. No molluscs whatever occur in Bl, the "peat"
layer with M. primigenius, but the conditions here are too acid
for molluscs to be preserved. The abrupt change here from the
brown silt with P. antiquus to the overlying peat may well indi-
cate a non-sequence. The lack of a good land mollusc fauna,
compared to Ilford, Ipswich and Trafalgar Square is particularly
striking: this could suggest that the area remained constantly
marshy throughout the sequence, with quiet conditions prevail-
ing, except for the possible hiatus between the two elephant
layers.
I would like to thank Dr M. P. Kerney (Department of Geo-
logy, Imperial College, London) for help with the literature and
Dr A. J. Sutcliffe for valuable discussion on the Aveley and Tra-
falgar Square sites and also for critically reading the manuscript.
References
Blezard, R. G. (1966). Field Meeting at Aveley and West Thurrock. Proc.
Geol. Aus., 77: 273-76.
Boycott, A. E. (1936). The habitats of Freshwater Mollusca in Britain.
J. anim. Ecol., 5: 116-186.
Franks. J. W. (1960). Interglacial deposits at Trafalgar Square, London.
New Phytol., 59: 145-152.
Sparks, B. W. (1964). The Distribution of Non-Marine Mollusca in the
Last Interglacial in South-east England. Proc. malac. Soc. Lond.,
36: 7-25.
Sutcliffe, A. J. (1964). The Mammalian Fauna. In OVEY, C. D. (ed.). The
Swanscombe Skull. A Survey of Research on a Pleistocene Site.
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West. R. G. (1969). Pollen Analyses from Interglacial Deposits at Aveley
and Grays, Essex. Proc. Geol. Ass., 80: 271-282.
West. R. G., Lambert, C. A. and Sparks, B. W. (1964). Interglacial De-
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Zeuner, F. E. (1959). The Pleistocene Period. London: Hutchinson.