ILFORD AND WANSTEAD.
165
sufficient to provide ice-rafts). This conclusion appears to be
the only one open to the field geologist, and to a certain
extent it is supported by the Palaeontological evidence.
In my opinion, however, the Middle Terrace drift as a whole
(including the brickearths) shows a very different state of things
in climatic conditions. I have argued in my paper that whether
we view this group of the Palaeolithic deposits from a lithological
or from a Palaeontological standpoint, we have to regard it as
representing a period of comparative equability, probably similar
to that obtaining in these islands at the present day.
A point of interest with regard to the physical geography of
the brickearth period is dealt with. From the occurrence of
Scrobicularia piperata at Ilford, of Paludestrina ventrosa at Crayford,
Grays, and Ilford, and of Littorina rudis at Crayford in the Middle
Terrace brickearths of those places it is argued that the Thames
whatever it may have been in earlier or later parts of the
Pleistocene epoch could hardly have been then a tributary of
the Rhine. On the contrary it must have then possessed an
estuary of its own, probably situated not very far to the east
of that of the present day. The upper beds of the Middle
Terrace drift show similar contortions to those observed in the
High Terrace series. The conclusion to be drawn is then
obvious, viz., that they have been contorted by river ice. From
this it would appear that comparatively severe conditions came
on once more towards the close of the Palaeolithic period.
The following tabular statement of the Pleistocene deposits
of the Thames is given in the conclusion of the Geologists'
Association paper :—
1. High Terrace Drift
2. Middle Terrace Gravels
(in part)
3. Middle Terrace Gravels
(in part) & Brickearths
4. Trail (Contorted Drift
series)
Older Palaeolithic. Cold
period.
Newer Palaeolithic. Genial
period.
Close of Palaeolithic Period.
Cold period.
A list of the more important papers and works relating to
the Pleistocene deposits of the Ilford district is appended to the
paper.
Martin A. C. Hinton.
January 27th, 1900.