74 EXPOSURE OF LONDON-CLAY AT CHINGFORD, ESSEX
that the original ochreous colour has been altered. These imple-
ments are doubtless derived from gravels analogous to the
contiguous middle and high-terrace deposits of the Hackney
district. A definitely Mousterian flake of "North London floor"
type has been found here. As it is slightly water worn, one
concludes that the gravel containing it is post-Mousterian. As
the Lea Valley Arctic bed at Temple Mills is associated with a
derivative Acheulean implement, and with flakes of perhaps
later date, it must be later than the well-known Arctic plant-
bed of Hoxne, which is definitely pre-Acheulean. The base
line of the Leyton and Hackney middle-terrace gravels is at
about the same level as the surface of the marsh land of the
present valley, and it seems quite obvious that the low level
gravel which extends to 20 feet below the marsh must be a later
deposit than the middle terrace gravel, through which its channels
have been cut.
In the locality described there are thus two beds of gravel
(Temple Mills and Hackney Wick) of different ages, but both
late Pleistocene, and in all probability there is a Holocene channel
in the centre of the valley. At a comparatively late date, the
upper part of these gravels was redeposited, and a bed of alluvial
clay laid down upon the top of them. A socketed bronze spear
head has been found at Hackney Wick three feet below the
top of the gravel. Including the 3ft. bin. of superincumbent
alluvial clay, it will be seen that 6ft. 6in. of alluvial deposits
have accumulated in the Lea Valley here since the Later Bronze
Age.
NOTES ON A FOSSILIFEROUS EXPOSURE OF
LONDON-CLAY AT CHINGFORD, ESSEX.
By ARTHUR WRIGLEY.
[Read 27th February, 1915.]
FOR many years past, a brickyard has been worked at a
short distance to the south of the Obelisk on Pole Hill,
Chingford. In the autumn of 1914, the section exposed was
as follows (in descending order):—
Surface, about 275 ft. O.D.
(1) Brown loam, slightly tenacious, with streaks of sand........4 ft.
(2) Very sandy loam, of light reddish-buff colour, with streaks of sand,
and ferruginous concretions ........11 ft.