Journal of Proceedings. xv
and Beading beds obtained north of the Thames had been found there.
He thought the Club might do good service to geology by carefully
investigating the strata referred to at Stifford.
At the conclusion of Professor Morris's remarks Mr. J. Spiller, F.C.S.
(Treasurer of the Photographical Society), took a photograph of the
group, and also obtained some negatives of the sections exposed in the
workings. A print from one of these, produced by the Autotype Company,
is given as a plate* accompanying this report. The photograph shows
one of the larger "pipes" in the chalk at Grays. The view is in the
South Central Chalk-pit, and the "pipe" is seen in shadow in the left
foreground of the picture—a wide and irregular-shaped cavity traceable
down to the floor of the pit, a distance of more than ninety feet vertical,
and containing deposits from the overlying Thanet sand and high-level
drift gravel.
Other "pipes," in a less advanced stage of erosion, are shown in the
centre and to the right of the picture.
The abandoned Western Pit, in which the South Essex Water Company
obtain their supply, was then visited. In the engine-house Mr. Walker
stated that, in 1860, the chalk had been worked to the level of the springs
in this pit over an area of some sixty-five acres, when attempts to go
deeper led to the discovery of an abundant supply of pure water and the
formation of the Company. The water passing over the gauge every
twenty-four hours was found to exceed 1,200,000 gallons, and even with
five engines at work it became necessary to brick-up fissures, so as to keep
the water down. Mr. Prestwich, in accounting for this volume of water
in an area where the superficial pervious beds do not exceed five miles in
extent, extends the receiving ground to the area of the Kentish chalk, as
well as to the northern chalk area which begins beyond Bishop's Stortford
and Dunmow; considering that the Thames, which opposite Greenhithe
and Dartford is not, even at high tide, more than fifty or sixty feet in
depth, would not intercept all the springs, † The daily quantity now-
yielded is about 1,300,000 gallons, of which 600,000 gallons is pumped to
waste to avert inundation. Owing to the low level to which the chalk has
been worked, the water is found near the surface, the engine-house floor
being seventeen feet above Ordnance datum, and the water in the well
varying from that line to eight feet below it.
This old chalk-pit would seem to be a capital hunting-ground for both
entomologists and botanists. There is plenty of undergrowth and chalk-
loving plants, the Clematis vitalba being notably luxuriant; but the
claims of the geologists were so imperative that no time was allowed for
herborizing. In the sections of the Thanet sand an abundance of the
* Our members will be pleased to learn that we owe this interesting and instructive
record of a pleasant meeting to the kindness of the three following gentlemen, who
reimbursed our Treasurer for the cost of the plate in the manner following:— Mr.
Meldola, £2 2s.; Mr. John Spiller, £1 Is.; and Mr. Harcourt, 10s.—Bd.
† Report of Water-springs at Grays.' Privately printed, 1860.