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CONTRIBUTIONS TO THE PLEISTOCENE
GEOLOGY OF THE THAMES VALLEY.
I. THE GRAYS THURROCK AREA,
PART II.
By MARTIN A. C. HINTON and A. S. KENNARD, F.G.S.
[Read December 14th, 1901. Revised October, 1907.]
CONTENTS.
I.—High Terrace Drift (Western Portion).
II.—Physical History of the Lower Thames Valley.
III.—History of the Mardyke.
IV.—Conclusions.
Appendix—Corrections to Part I.
The first part of this paper was published in the Essex
Naturalist for 1900 (vol. xi., pages 336—370). The object of
the second part is to deal with the physical side of the questions
involved in a study of the Pleistocene deposits of the Thames
Valley. The great delay which has arisen since the reading of this
part has been occasioned by the highly complicated nature of the
subjects dealt with, coupled with our reluctance to send it to
press without first testing its arguments by every available
means. In our opinion the paper has gained greatly in many
respects from this delay. We have now, as before, to thank
numerous friends for their valuable assistance. To the list
previously given we would add the name of Mr. William
Whitaker, F.R.S., who materially aided us from his vast store
of knowledge concerning Thames Valley geology.
I. HIGH TERRACE DRIFT (Western Development).
During the course of our field-work in 1901 we became con-
vinced that two quite distinct sets of deposits had been
confounded under the designation of the High Terrace Gravel.
One series undoubtedly does belong to the High Terrace of the
Thames Valley, the other is to be regarded as the product of a
very interesting feature in the evolution of the present from
out of the Pleistocene physical geology, or rather geography, of
the district. The deposits classed with the High Terrace by us
are those which form the subject of this section of the paper.
All that we have to do here is to describe their distribution in
the western portion of the district (those of the eastern portion
having already been described in Part I.) and the sections
exposed in them.