PLEISTOCENE DEPOSITS IN BILLERICAY, ESSEX 167
in the Gravels as a whole is made of angular quartz grains and
closely resembles in size and colour the local Bagshot Sand. The
proportion of this grade increases markedly towards the base of
the deposit.
TABLE 1
Pebble Gravel
(37399410, 67309425, 67379418, 67329425, 67509418, 67479435
67509438, 67509445, 67499499, 67509453, 67499425, 67609465
67609460, 67359441-67259441, 67289449, 67789386, 67679474
67969517, 67849512, 67909518 - 67819530 - 67869535 - 67939532
Bagshot Sand
67559485, 67639500, 67669466, 67659478, 67639483, 67709477
67639446, 67529485, 67419480, 68029498, 67979510, 67259443
67289422, 67509418, 67479435
London Clay
67749476, 67639436, 67929455-67989435-68139468-68269458
68459493 - 68039485 - 68239470 - 68509480, 68159290, 68209278
67819202
Glacial Gravel.
67459348-67509318, 67819202, 68089326, 68109321, 68149310
67959373, 68459370, 68459343 - 68329354 - 68289378
Boulder Clay
67259442, 67509505, 69089520, 68379676 - 68409692 - 68589682-
68689702, 68519668 - 68599679
(All grid references are in 100 km. sq. T.Q.)
The temporary exposures of Pebble Gravel are numbered in
Fig. 1 and the structural details are illustrated in Fig. 3. National
Grid references to all temporary exposures are listed in Table 1.
At locality 1, a 4 feet (12 m) wide trench 9 feet (2.7 m) deep
was cut between Chapel Street and Billericay Post Office. Minor
excavations were made parallel to and at right angles to this
trench. These sections showed a series of saucer-shaped hollows
in the Bagshot Bands filled with flint pebbles in their coarse sandy
matrix and mixed with varying amounts of reworked Bagshot
material. The depressions varied from a few inches to 4 feet
(1.2 m) in depth and from 6 to 20 feet (1.8-6.1 m) in diameter. One
much larger depression was uncovered some 35 feet (10.7 m) from
the road. This measured 30 feet (9.1 m) across and up to 9 feet
(2.7 m) deep and extended north-south without any change in
cross-section for at least 20 feet (6.1 m) (Fig. 3A). The Bagshot
Sands below this channel-like feature were strongly reddened for
up to 3 feet (.9 m) from the channel base and contained arcuate
bands of tough fissile ironstone up to 2 inches (5 cm) thick. These