240
FOWLNESS.
suspended in the water for a longer period, and much of it is carried
away into the sea beyond. The remainder is left on the neighbouring
shores, caught in depressions of the sand, or of the mud deposited
on a previous occasion. As soon as a film of clay prevents constant
movement of the surface, the sea-grass Enteromorpha takes possession,
and helps yet further to arrest the clayey particles by filtration between
its fronds.
Then saltwort appears on the now firm mud, and this detains the
floating refuse, straws, wood, cinders, &c., all helping to increase the
deposit. When the bank is above the reach of neap tides, coarse
grasses and other semi-marine vegetation continue the work. The
earth deposited under the above conditions is of necessity devoid of
any trace of stratification. Such areas, before enclosure, are termed
"saltings" or "salt marshes," being interspersed with deep, narrow
sinuous channels, which every tide fills. The boundaries of the fields
in the enclosed land are, in many places, these original creeks.
When the surface thus raised to the level of ordinary tides is of
sufficient area to render it worth the trouble of enclosing, a bank of
earth, sufficiently high to keep out even the spring tides, is raised
round it, and, if necessary, faced with stone. As a rule, however, such
facing is only wanted where the new wall is too near the edge of the
patch of saltings, or where by some change in the currents the
saltings that once existed outside of the enclosed land have been
swept away, and the enclosure is threatened with a like fate.
The walls in such cases are faced with blocks of Kentish ragstone
and chalk wedged down, generally without cement, between rows of
piles driven well into the bank. In storms, however, considerable
lengths of wall are frequently stripped of this protection, which has to
be immediately replaced.
The land once enclosed sinks from near spring-tide level to that
of half-tide, owing chiefly, if not entirely, to drainage. The loss of
organic matter, as well as that of water, may be a chief factor of this
reduction in thickness.
At Church End, the highest part of the island, the section in the
churchyard is as follows : Mould, 2 feet; clay, 2 feet 6 inches;
clayey sand, 6 inches ; total, 5 feet to sand charged with salt water.
At the Lodge, the clay appears on the surface, the mould being
absent. At Court's End, the surface soil to the depth of 4 feet
6 inches is a uniform clayey loam, resting upon sand as before.
A bed of detrital shells is marked on the Ordnance Map as