Geoscience Reference
In-Depth Information
FIG 164. Looking northeastwards across Weston-super-Mare, with the headlands of We-
ston Woods (Fig. 156, d4 ) and Sand Point ( d5 ) behind. (Copyright Dae Sasitorn & Adri-
an Warren/www.lastrefuge.co.uk)
The striking features of the stretch of coastline around Weston-super-Mare are
the isolated sections of Carboniferous bedrock that form the strongly projecting head-
lands of Brean Down ( d3 ), Weston Woods ( d4 ) and Sand Point ( d5 ). The combination
of hilly headlands with wide bays provides attractive views (Fig. 164), though the
strong tides and abundant availability of muddy sediment make many of the beaches
too muddy to attract many visitors. The headlands, along with the offshore islands of
Flat Holm ( d6 ) and Steep Holm ( d7 ), are the tops of ridges that are the relicts of faulted
folds made largely of Carboniferous Limestone, deformed during the Variscan moun-
tain building and then eroded and draped with Triassic sediments. More recent river
erosion has subsequently modified the hill form of the Carboniferous features. Finally,
Flandrian sea-level rise has deposited yet another layer of sediment on the low-lying
land (now beaches) between these old hill features.
Between Clevedon and Portishead the coast displays another example of a Var-
iscan faulted fold, although in this case it runs northeasterly, forming a ridge parallel
to the coast. Inland from the ridge is the Gordano Valley, with the M5 motorway run-
ning along its southeasterly slope. The low ground of the Gordano Valley was probably
carved out by an episode of erosion when the main River Severn occupied this part of
its valley slope. Mapping of the bedrock in this area shows that the present-day coastal
ridge was also a ridge in Triassic times, a relict of the early Variscan landscape similar
to the Weston-super-Mare headlands and Westbury Valley in the Mendips.
Search WWH ::




Custom Search