RECENT DISCOVERY OF A DENE-HOLE AT GRAYS. 155
the Manager to the site of the new discovery, which is at the
extreme northern end of the quarry.
At this point the Thanet Sand, with its capping of Pleisto-
cene river-gravel, has been worked back in earlier years, and
forms a vertical cliff some hundred feet behind the present
face of the underlying Chalk, and upon the wide ledge so formed
a line of rails for the quarry railroad is laid down.
Recently, it was desired to form a second line of rails close
up to the cliff of Thanet Sand, and the latter was being slightly
trimmed back to allow this to be done, when a cavity was broken
into at the very base of the cliff, which proved, on further excava-
tion, to be a dene-hole, similar to, but smaller than, those so
well known at Hangman's Wood,1 11/2 mile to the east; the pit
was found to extend, in part, under the cliff and, in part,
beneath the ledge formed by the removal of Thanet Sand in
past years.
This pit was an undoubted dene-hole, of the usual double
trefoil in its plan (Fig. 1), its longer axis running from north-
west to south-east.
The pit had been excavated by its constructors in such a
way that the "Bull Head" Band of green-coated flints between
the Chalk and Thanet Sand formed its actual ceiling, without
any intervening chalk being left, as in the Hangman's Wood
dene-holes, to form a substantial roof. Probably on this ac-
count, falls of flints and sand from the ceiling had taken place
in two of the northern chambers (marked x x in the figure);
and this fact, coupled with the presence of some threatening
joints in the chalk of the end wall of the northern terminal
chamber, had probably dissuaded the original constructors from
proceeding further with their excavations, and this accounts
for the unusually small size of this terminal recess.
The floor of the dene-hole was approximately 44 feet below
the original surface of the ground, and the shaft, some 21/2 feet
in diameter, was in the roof of the short, central connecting
corridor between the two trefoil ends of the pit, but is now choked
with a heterogeneous mass of fallen gravel from above. No
grooves worn by ropes could be detected at the lower end of the
plugged shaft, but three foot-holes were seen in the chalk walls
below the shaft, two of these being in the eastern wall, one
1 See "Essex Naturalist," 1, 1887, pp. 225-276.