148
EPPING FOREST
Age, exist at Loughton, Buckhurst Hill, and
Woodford. And the small patch at Queen Eliza-
beth's Hunting Lodge, with two others between
that building and Fairmead Lodge, may possibly
be of the same period.
The Boulder Clay, though it may be seen east
of the Roding as far south as Chigwell, and west
of the Lea at Finchley, has not hitherto been
detected within the present Forest except at the
extreme north, beyond Epping, where it forms
most of the surface of "The Lower Forest."
There are also two smaller patches close to the
town of Epping. Possibly some future section
may reveal it in, or on, the gravel of Woodford,
Buckhurst Hill, or Loughton. It may be described
as a confused mass of rocks of various ages in a
matrix of bluish-gray or buff-coloured clay. The
chief ingredients are chalk and flint, then come
rocks and fossils belonging to the Lias and Oolite
formations. Belemnites and Gryphceas are very
abundant. The constituents of the Boulder Clay
have evidently been derived from the north, not
from the south, but it is impossible here to discuss
the various theories held by geologists as to the
particular form of ice-action, whether ice-sheet,
icebergs, or coast-ice, which has produced the
Boulder Clay of the Eastern Counties.
In the most southerly portion of the Forest,
about Leyton and Leytonstone, Snaresbrook and
Wanstead, the surface is largely composed of
gravel of lower level and later date, belonging to
the present systems of the valleys of the Thames
and Lea. It was deposited, however, when those
rivers flowed at a somewhat higher level than
they now do, and having more fall, brought down
coarser material. And in the alluvium or marsh
deposits of the Lea and Roding we have the
lowest in level and latest in date of all the geo-
logical formations in, or bordering on, the Forest
district. Sections in these beds have been common
in the neighbourhood of Walthamstow from time to
time during the last thirty years, the East London
Waterworks Company having made many addi-