THE ESSEX FIELD CLUB.
275
good and sagacious animal immediately turned and swam for the shore, whence
it took his master home safely, but on reaching the stable it lay down and died !
Opportunity in this journey was given us for observing a "kettle" or
"keddle" in operation, a local fisherman, Mr. Philip Cripps, kindly giving a
demonstration of this curious mode of fishing as practised on the Maplin sands.
The keddle is a net of many yards in length, and about a yard wide, set up
vertically with stakes, but bent at the middle to a right angle. This angle is
pointed seawards and occupies the lowest point. At this point a bag net is
attached so that all the fish occupying the area included in the angle are
entrapped as the tide recedes.
At the keddles Mr. J. W. Hepburn showed an experiment demonstrative of
the character of the sand forming the Maplins. Though sand-coloured on the
surface, it proved to be black immediately beneath. Tested with hydrochloric
acid, both the surface and the sub-sand frothed violently, due to the escape of
carbonic acid gas, indicating the presence of abundance of carbonate of lime in
the sand. The escaping gas smelt strongly of sulphuretted hydrogen (afterwards
identified in the laboratory by the usual tests), proving the presence of sulphides
in the sand. Mr. Hepburn stated that shells of Foraminifera were observed when
the sand was examined under the microscope, but he did not think that they were
sufficient to account for all the carbonate of lime present. It appears that the
black colour of the sub-sand is due to organic matter, and it is found rapidly to
undergo oxidation when exposed to the air, leaving the sand the usual colour.
This accounts for the fact that, while the Maplin sands are black an inch below the
surface, the surface itself is an ordinary sand-colour. The organic matter and
carbonate of lime might both be due to the decay of animal organisms in the
sand, e.g., the lug worms, whose casts are extraordinarily numerous. Some
members of the club suggested that they were more likely due to the sewage
refuse which is emptied in the North Sea outside the Maplins. This latter
hypothesis was afterwards disproved by finding on Newlands Farm, about five
feet below the surface, black sand identical in appearance and properties, which
must have been deposited some hundreds of years ago, and certainly long before
London sewage was conveyed to the North Sea. Nevertheless, it is quite
possible that some of the carbonate of lime is due to particles of chalk carried
down in flood time from the chalk hills of the Thames Valley. The sulphides in
the sand are unquestionably due to the reduction of the sulphates in the sea water
by the organic matter of the black sand.
We may here mention that Fowlness Island, although standing at the mouth
of a river, is not a delta in the sense of its consisting of material brought down
by that river. It is simply a portion of the mainland which has been separated
by creeks, and indeed the river itself is more of a marine creek than a freshwater
channel. If the geological history of the regained land of the Essex shore be
ever written, this deposit will have to be taken into account. It is possible that
the calcareous constituents may be due to sea shells reduced to a state of extreme
comminution.
Resuming the trail or "Broomway," the drive was continued to Fisherman's
Head, and so to East Newlands Farm, where the Club was warmly welcomed by
Mr. and Mrs. John Hepburn. In one of the barns a substantial luncheon was
laid out, which had been brought over from the "Royal Hotel," Burnham, in
the sailing boat "Victoria." The fresh air blowing over seven or eight miles of
sand, and the half hour's walk to the keddles, had given us the appetites of—Danes