THE CHANGING COASTLINE OF ESSEX 91
which occur subsequent to the formation of the marsh bar;
they are not instrumental in initiating the feature.
On the seaward side of the ridge the mud flat is at present
being colonised by Zostera, Salicornia, Spartina stricta, etc.,
and converted into a salting. As this proceeds, the shell and
sand ridge will become an integral part of the marsh,
possessing a form similar to that now well within the
enclosed land of the Dengie Marshes.
The effect of storm surges on the Essex coastline remains
to be considered. They are meteorological in origin and are
Fig. 7. The distal end of the marsh bar off Sales Point.
characterised by abnormal high water. (Doodson, 1929.)
They arise when a deep depression passes quickly from west
to east across the northern part of the North Sea. Whilst
the depression is over Scotland, the winds in the Thames
Estuary blow from the south-west and often reach gale
force, causing the surface water of the sea to move out of
the estuary and pile up towards the north. As the depression
travels quickly towards the Baltic, the winds veer to the
north-west or north and the water surges back into the