Geoscience Reference
In-Depth Information
FIG
60.
The Lizard coastline. Note the contrast between the jagged coastal cliffs and the
flat inland landscape. (Copyright Dae Sasitorn & Adrian Warren/ www.lastrefuge.co.uk)
Landscape C: Cornish killas
Most of the bedrock of West Cornwall is Devonian sediment, folded, faulted and - loc-
ally - altered during the Variscan mountain-building episode (see the general section of
this chapter). The Devonian sediments, known to miners and quarrymen as
killas
, have
been less resistant to landscape weathering and erosion than the granites (
A
) and the
Lizard Complex (
B
), and so have been preferentially eroded to form lower landscapes.
All the major bays and estuaries of this Area, such as St Ives Bay (
c4
) and the Carrick
Roads at Falmouth (
c7
), are situated in killas areas for this reason. The Variscan fold-
ing and faulting that deformed the killas has also locally influenced the directions of
valleys and their slopes, which have picked out variations in the killas layering, giving
an east-west grain to the landscape (Fig. 61).
