16
The Essex Naturalist
Archaeology
The terraces of the Lower Thames have yielded many Palaeolithic artefacts,
mostly flint, in the forms of flakes, cores (from which the flakes were struck) and
hand axes. Views on the significance of archeological industries are changing.
Formerly, an early Clactonian Industry was recognised, which used relatively
simple technology to produce cores and flakes, thought to give way to the
Acheulian Industry which included hand-axes as well as cores and flakes. It is
now thought that the distinction is not valid and that the presence or absence of
hand-axes may reflect factors such as the availability of suitable raw material.
However, the Levallois industry is distinct from the earlier industries in that the
cores indicate a high degree of preparation so that the type of flakes struck off
could be pre-determined.
The Orsett Heath Formation and the Corbets Tey Lower Gravel yield only
artefacts of the Acheulian and Clactonian type combined. However, from the
Corbets Tey Upper Gravels to the East Tilbury Marshes Lower Gravel, artefacts
of the Levallois technique are found. During the time of the Ipswichian
Interglacial, only occasional reworked artefacts are known, suggesting there was
no human occupation, possibly because humans were unable to re-enter Britain
after the OI. Stage 6 cold stage due to rapid sea-level rise. Thus archaeology does
have some value in resolving stratigraphic problems.
Comment
It is recognised that there is a mismatch between the two interglacials
recognised by pollen analysis (Hoxnian and Ipswichian) and the four terraces
(Orsett Heath, Corbets Tey, Mucking and East Tilbury Marshes), the warm
climatic oscillations (OIS 11, 9, 7 and 5e) shown by the oxygen isotope curve
and their associated amino acid ratios. The fauna and archaeology also favour
the extended stratigraphic sequence. The tension between the Palynological and
the other approaches remains unresolved and as a result there are currently two
stratigraphies for the Lower Thames, a shorter one based on the pollen and a
longer one that can be related to the OI curve (Table 1).
Gravel aggradations are rarely dated per se but have their stratigraphic
position fixed by their relation to interglacial deposits. Thus errors in fixing the
age of the warm stage deposits repercusses to the cold stage gravels.
The Terrace Sequence
In various areas, sequences of terraces have been recognised and given local
names (Table 3). At the moment, this means we have a large number of terrace
names, but as we are still in the process of completing the correlation, it will
allow us to change the correlations if necessary and so avoid ending up with the
same name being applied to two different terraces due to wrong linkages as has
happened in the past; for instance the Taplow Terrace in Essex has been proved
not to be the equivalent of the Taplow Terrace upstream of London.