Vol. XXVII—Part XI.
April, 1945—Sept., 1945.
THE
Essex Naturalist:
BEING THE
Journal of the Essex Field Club.
SOME GEOLOGICAL AND PREHISTORIC RECORDS
ON THE NORTH-WEST BORDER OF ESSEX.
By S. HAZZLEDINE WARREN, F.G.S.
(Being a Presidential Address given on 31st March, 1945)
Including a Report on Holocene Mollusca by A. Santer Kennard,
A.L.S., F.G.S.
WESTLAND GREEN (Pebble Gravel).—Since the publi-
cation of my Address on the "Drifts of South-West
Essex" I have had the opportunity of examining an unusually
good exposure of the presumed Pliocene Pebble Gravel in a big
pit at Westland Green, near Little Hadham. In that address I
referred to the early course of the Lower Thames having been
far to the north of its present valley, and outlined the evidences
(with references to the literature), which show that the Kentish
tributaries of the Thames flowed at least as far north as Epping,
Stock and Little Oakley, without having joined the main river,
which was therefore not south of the general line, Ware-Chelms-
ford-Harwich, and may well have been farther north.
I also quoted the fact that erratics from the west, some
from as far away as Wales, occur in the early drifts of the Goring
Gap ; as long ago as 1823 Buckland traced the routes through
the gaps in the Cotswold Hills along which streams of stones
passed from the valley of the Severn into that of the Thames.
Below the Goring Gap further supplies of stones from the west,
mainly small quartz pebbles, entered the Middle Thames through
gaps in the Chilterns. Thus the key-facts in tracing the course
of the early Severn-Thames are stones from the west along the
main stream, and the absence of such stones in the southern
tributaries which carry Lower Greensand chert instead. In
sharp contrast with the above-mentioned groups, the later Glacial
gravels are characterised by Lincolnshire flint, basalts from
the North of England, and schistose and granitoid rocks from
Scotland and Scandinavia.