IN THE VALLEY OF THE CAM, ESSEX.
141
this evidence have been given in the Essex Naturalist (ante pp.
44, 49—50 and 54), but the general conclusions are of more than
local interest. The beds found are for the most part loamy or
clayey.
At the head of the valley, various wells at Quendon and Rickling
show irregularities in the thickness of the Drift, the Chalk coming to
or near the surface in some places, whilst it is nearly 100 feet to it
sometimes.
Further north, at Newport, we have the greatest thickness of Drift
hitherto recorded in the South of England, and then without reach-
ing the base. At one spot a well reached Chalk at 75 feet, whilst
about 150 feet off that rock crops out, showing a slope of the chalk-
surface of 1 in 2. The most interesting of all the wells is at the
Grammar School, where, after boring to the depth of 340 feet, the
work was abandoned without reaching the Chalk, the Drift in this
case reaching to a depth of about 140 feet below the level of the
sea, though the place is far inland. The Chalk crops out about 1,000
feet eastward and at but little lower level, so that there is a fall of
about 1 in 3 over a long distance.
At and near Wenden the abrupt way in which Drift comes on
against Chalk has been seen in open sections. Two wells have
shown a thickness of 210 and of 296 feet of Drift respectively, and
as the Chalk comes to the surface, at a level certainly not lower,
only 140 yards from the latter, the chalk-surface must have a slope
of 1 in less than 11/2, and this surface must rise again on the other
side, as the Chalk again crops out. The Drift here reaches to a
depth of 60 or 70 feet below the sea-level.
At Littlebury, still further north, many wells have reached the
Chalk at slight depths, in some cases next beneath the soil, in others
through a little River Drift (gravel); but in the centre of the village
a boring 218 feet deep has not pierced through the Drift, which
reaches to 60 feet below the sea-level. As in a well only 60 yards
west, and slightly higher, the Chalk was touched at 6 feet, there must
here be a fall of the chalk-surface of about 1'2 in 1. Eastward too,
on the other side of the valley, the Chalk rises to the surface.
It is noteworthy that in this last case the Geological Survey Map
(Sheet 47) shows no Glacial Drift, and rightly so, for in no place
does that formation come to the surface, being wholly hidden under
narrow spreads of Alluvium and of River Gravel, together only about
a quarter of a mile broad at the site of the boring. Without the