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The Historical Stage (Post-Glacial)
in the Lea Valley
By JOHN F. HAYWARD, Ph.D., M.Sc., F.G.S.
1. INTRODUCTION
When the writer became interested in the geology of the
Lea Valley the first channel section which he examined
was near Carthagena Lock on the Essex side of the river.
There was at that time no evidence as to the age of the deposits
which contained much derived material. This was later found
to include a percentage of shells encrusted with calcium carbon-
ate, indicating that they were derived from deposits which,
from their association with a dug-out canoe could be given a
Roman date. Hence the Carthagena Lock deposits were post-
Roman. The earlier stage has since been named the Rammey
Marsh Stage [Hayward, 1958]. The shell marls of Cartha-
gena Lock were capped by a bed of grey loam, and this by the
characteristic yellow-brown Marsh Clay of the valley. All
these deposits were laid down in historical times and the belief
that the geologist should not concern himself with very recent
events could not be upheld. The beds were stratified, and only
the stratigrapher, using Stratigraphical methods, was trained
to study them.
After the channel at Carthagena Lock had been described it
transpired that Mr. S. Hazzledine Warren had examined a
section not far off and his description was incorporated as an
appendix to the present writer's paper [1957a]. The section
confirmed the author's findings, but when he traced it in the
field it was evident that it had been cut back since Mr. Warren
examined it, as an additional bed was visible near the top. The
lowest beds were below water.
The previous account was written in 1954, though it was
not published until three years later. At that time there were
various unsolved problems and these have been largely clarified
by fresh field evidence. The object of this paper is therefore
twofold, namely to complete the description of the Broxbourne
section just mentioned, and to discuss the relationship of the
various deposits in different parts of the valley. All are now
included in the Historical Stage [Hayward, 1958].