116 ON THE GRAVELS NEAR BARKING SIDE,
This section was on the patch mapped "Hill Gravel of doubtful
age." I should be inclined to call it a Pre-Glacial Hill Gravel.1
Patches of Boulder Clay and Loam belonging to the Glacial
Formation are mapped at Chigwell Row (266 feet O.D.), and on the
slopes of the hill below are some small patches of gravel.
Then we come to the large patch on which Barking Side stands.
It is described by Mr. Whitaker (pp. cit. p. 410) as one of several
detached masses of a high terrace of River Drift "separated from
the rather lower sheet to the south by an outcrop of London Clay,
partly very narrow." He adds that this "large mass stretches irregu-
larly eastward from near the Roding, opposite Wanstead, by Barking
Side and Aldborough to the south-eastern part of what used to be
Hainault Forest by Padnal Gate, and northward to Fairlop Plain.
It seemed as if the London Clay came up through the gravel in
places, as half-a-mile and more south-westward of Barking Side,
between that village and Aldborough and round Aldborough
Gate."
This gravel is mapped as extending from a level of about 120
down to 50 feet above the sea, and there is a gravel pit at Carswell
at the lower end of the patch. The section shows some 15 feet of
well stratified gravel and sand. Mr. Crouch tells me that the
greatest thickness of gravel is 21 feet, and when Mr. T. V. Holmes
and I visited the pit on June 15th last, he showed us a place where
the London Clay was being dug into below the gravel. Patches and
lines of sand, sometimes rather loamy, occur occasionally. Here and
there the gravel is slightly contorted and in two or three places small
faults, or more probably slips, are to be seen.
The gravel consists mainly of flint pebbles and subangular flints.
I also noted a few fragments of Lower Greensand Chert, some, not
very much, small quartz, and the following stones which are probably
erratics derived from the Glacial Drift:
1 See S. V. Wood, Quart. Journ. Geol. Soc. 1868, vol. xxiv , p. 466 ; Whitaker, Geol. of Lond.
vol. i., p. 297.