116
Primaeval Man in the Valley of the Lea.
the "floor" are occasional seams and blocks of London-clay,
brought from a short distance to the north-west, where the
clay comes to the surface. As a rule there are no very large
blocks of flint or other large stones on the "floor." The
non-waterlaid covering mass often disturbs the "floor,"
ploughs it up, and pushes underneath it. The twisting,
contortion, and undulation of the material above the "floor"
seem to prove that it was laid down by moving ice from the
north. This ice-deposited "trail" and "warp" is full of
small whitish pebbles, fixed in the tenacious material at
various angles. Abraded and whitened implements are also
met with in the "trail," examples no doubt caught up from
Fig. 6.
old exposed surfaces by the ice-sheet, and brought from a
distance to their present position. No Palaeolithic implements
occur above the "trail"; the "trail" seals up all the relics
of the Palaeolithic age, and, as far as the evidence of north-
east London goes, Palaeolithic man had quite retired before
the "trail" and "warp" were deposited. When implements
are found on the surface, the ground may have been denuded,
and the implements exposed.
Fig. 6 is a measured section through the "floor" facing
west, on the other side of the section, illustrated in fig. 5;
the "floor" is seen at from 3 ft. 6 in. to 4 ft. 10 in. beneath
the surface; muddy trail, with sand and a few stones, is
present at b and c; d is humus. In the direction of the
arrow, from north to south, the "trail" is seen pushing