218 EXCURSION TO WALTON AND FRINTON.
and is at some points a fairly steep slope. It is often masked by
a mass of Crag sand, forming a talus of gentle gradient, on which
the collector can lie prone, and fill his boxes at leisure, regard-
less of comment from Philistines occupying the cliff-top or the
beach. The several beds extend inland, and outcrop succes-
sively on the western slope of the Naze peninsula, as shown on
the Geological Survey map.
The effect of denudation on the various beds are characteris-
tic for each. The porous and fairly coherent gravel on the top
offers a vertical face. Never being saturated by the most pro-
longed rainfall, it remains in place till dislodged pebble by
pebble, as the supporting grains of sand are removed by direct
lateral lashing of rain or spray. The water it receives on its
level surface sinks in, and escapes westward over the edge of the
underlying clay into the Crag below. This clay, originally
assigned to the Chillesford clay, which in Suffolk is interbedded
with the Crag, is probably representative of the Post-Glacial
freshwater bed of Clacton cliff, a correlation now published for
the first time, and based partly on its lithological character and
that of the superincumbent gravel, and partly on the presence,
about midway in its thickness, of a seam of peaty matter and
fossil wood, as at Clacton. This seam was of limited extent, and
has now disappeared with the recession of the cliff, but fortu-
nately some of the wood is preserved in the Club's collection at
Stratford. This Post-Glacial clay or loam offers a nearly
vertical face, being sufficiently sandy to absorb and discharge
rainfall without becoming pasty or slipping. The Crag below it
has a steep face for a foot or two, merging into the talus. Its
basement bed of water-worn bones, teeth and pebbles, derived
from the denudation in the Crag period of the London clay and
of some deposits of intermediate age, is seldom visible, but a
shark's tooth badly damaged, and a large piece of bone, were
among the finds of the day. The London clay, rising to some
30 feet from the beach, has generally a steep face, but here and
there springs oozing from the Crag have caused heavy slips,
breaching the bank, and furnishing the waves with broken and
semifluid material, incapable of resisting their transporting
power.
Notwithstanding the evident recession of the brow of the
upper cliff, there is no perceptible difference between the high-
water line of the old and the new Ordnance maps. This may