PALEOLITHIC INDUSTRIES, CLACTON AND DOVERCOURT. 27
yields the Levallois industry which is generally considered to be
contemporary with the Twisted-ovate group. And the Clacton
channel fauna is in turn earlier than the fauna associated with
the Twisted ovate group, but later than the fauna of the early
Taplow Terrace deposits of Little Thurrock. This narrows
down the dating of the Clacton channel, with its Clactonian
industry, to the end of the Grays Inn Lane epoch, and also as
coming between the two deposits of the two Thurrocks.
Mr. Clement Reid emphasized the unusual proportion of dry
soil plants in the Clacton bed. Mr. A. Santer Kennard also
states that the shell fauna indicates the absence of the wide
expanse of marsh that borders our rivers of to-day. It would
appear then that the state of "rejuvenation" and active
deepening of the valley was maintained to the end, and that
the state of river "maturity" was never attained.
Before maturity or base-level with an associated marsh
area was reached, the Clacton channel stage was closed by a
notable submergence.
At this point one must consider the levels a little further.
Working with an Abney level from the nearest registered points
on the 6-inch maps, and also from high tide, I make the highest
surface level over the Clacton channel deposit to be about 41 or
42 feet above O.D. This is on the east side of the channel, and
the present surface steadily falls to the west over the site of the
channel to the Jay Wick marshes.
The main Elephant-bed (purely freshwater) extends from
about 10 feet below (if not lower) to about 10 feet above O.D.
Overlying this there is a less fossiliferous, hard, dark-coloured
clay, apparently about 20 feet thick, that lies between 10 and
30 feet above O.D. I am not clear where the evidence of brackish
water first appears, as I have never seen the lower part of the
cliff fully exposed. I found one fossiliferous layer in the middle
of this Hard Clay at a level of about 17 feet O.D. that yielded
a good representation of the same dry-soil plants, and land and
freshwater shells11 as the main Elephant-bed below. I am not
entirely satisfied with the early records that describe this clay
as estuarine : it certainly is not entirely so.
The true estuarine deposits that overlie the Clacton channel
11 In the Quart. Journ. Geol. Soc. vol. lxxix., p. 611, the letter "l" should not have appeared
to the "Red Sand and Shells." In the footnote also the letter "p" is a printers' error for "h."