PLEISTOCENE DEPOSITS IN BILLERICAY, ESSEX 169
tains fragments of ironstone and locally the ironstone formation
post-dates the small-scale faulting. The extremely sharp breaks
made by the faults seem to imply that the Bagshots were much
more competent than they are now—a toughening that may
perhaps be attributed to perma-frost conditions.
At locality 2 excavations showed a channel almost identical
in shape, size, orientation and content with that described above.
It is just conceivable that the two sections showed the same
channel. Here, however, a discontinuous more sandy layer divided
upper sandy gravel from lower more clay-rich gravel (Fig. 3B).
Marginal to the channel were thinner pocketed gravel deposits
and nearby (at Sun Corner) the Bagshots are overlain by but a
few inches of gravel.
At locality 3, the eastern edge of Billericay Hill, excavations
covered an area of about 100 by 30 yards (91 by 27 m) (Fig. 3C)
and again exposed gravel and Bagshot Sands. At the higher,
western end of the excavations, gravel pockets up to 6 feet (1.8
m) in depth and 40 feet (12 m) across were let into the sands. The
largest pocket carried a 3 feet (.9 m) thick clay band with few
pebbles. This band expanded laterally such that the gravel was
replaced by a mass of clay containing two lenticles of gravel. The
latter measured 20 feet (6 m) across and were up to 9 inches (23
cm) thick. Immediately below the gravel the Bagshots were
disrupted—ironstone bands were broken for example—and the
reworked rubble was mixed with scattered flint pebbles. Below
this mixed zone the Bagshots were horizontal but further down-
hill their bedding was seen to be gently undulating and one
prominent clay band was dropped downhill by small normal
Fig. 3. Sketch sections and plans of some of the temporary exposures.
Pebble Gravel—coarse ornament, Bagshot Sands—fine stipple.
A. Locality 1 (67479435). Section measures 80 by 12 feet (24 by
3.6 m).
a. sandy lenticle,
b. conspicuous Bagshot debris.
B. Locality 2 (67509418). Section measures 30 by 9 feet (9 by 2.7
m).
a. sandy lenticle,
b. Bagshot sand in matrix,
c. clay-rich gravel.
C.1. Locality 3 (67609460). Plan. bc = 90 feet (27 m) and is north
south. Base of gravel isopachytes at 2 feet (.6 m) intervals
below present land surface.
C.2. North-South section, be of Fig. 1.
C.3. East-West section of C.1. and extension eastwards.
D. Hanningfield Till succession around Stock Road Potash Road
junction (68409690). Flint and chalk always present, dominant
cobbles indicated. Total thickness 18 feet (5.5 m).
E. Sketch section locality 7 (67789204). Showing relationship be-
tween glacial gravel spreads and contortions in upper gravel.
Section measures 30 by 8 feet (9 by 2.4 m).