Geoscience Reference
In-Depth Information
er areas. A road running behind this sea wall provides easy car, pedestrian and railway
access to a wide range of beach-barrier and shore environments (Figs 299 and 300).
In Figure 300, the tidal channel is the straight, light-coloured feature running in-
land towards Wells-next-the-Sea. The channel has been straightened by the building of
a sea wall along the near side of it. The large, dark, tree-covered ridge directly behind
the beach in the foreground is the main storm-built barrier, stabilised in the 1850s by
planting pine trees on its wind-blown dunes. The beach itself shows at least four dis-
tinct, slightly sinuous ridges of sand, more or less parallel to the tree-covered barrier.
These ridges tend to be driven landwards during storms and may eventually be added
to the barrier. The ridge closest to the tree-covered barrier is the lightest in colour be-
cause it has been capped by dry, wind-blown dunes formed within the last 20 years. Be-
hind the main barrier, Wells Caravan Site can be seen, built upon meadows formed by
draining ground that was previously salt marsh. These drained meadows were flooded
when the sea wall was breached during a storm in 1978. This whole array of coastal
features has been constructed and altered during the last 6,000 years, since the sea rose
and flooded the land up to its current level.
FIG
299.
Pattern of coastal sediment near Wells-next-the-Sea (Fig. 294,
c3
).
Figure 301 shows the large barrier feature of Blakeney Spit (
c4
) in the far dis-
tance, along with a number of smaller barrier ridges forming a discontinuous, sandy
strip in the middle distance, on the seaward side. Behind these barriers, in the centre
of the photograph, is a large area of back-barrier salt marsh, completely covered by
the highest tides and supplied with sea water and sediment by a complex network of
channels. The sharp southern edge of the coastal strip (on the right-hand side of the
picture) is marked by a clear, straight line that truncates fields on the hilly ground to
the south. This edge is thought to mark an old cliff line formed during the Ipswichian
(about 130,000 years ago), when the sea was at a slightly higher level than it is today.
Between the Ipswichian warm episode and today, the sea retreated for hundreds of kilo-
metres as ice advanced into this area. When the ice melted, the sea advanced back to
its present position.
