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'Hard' rock sea cliffs
'Hard' rocks are defined by two basic forms:
- Cliffs in highly resistant rocks such as basalts, granite and harder limestones
where erosion is slow and movement results from splits along joints and faults.
They are usually vertical in form and may include blow-holes, platforms and
stacks;
- Resistant but exposed rocks where weaknesses result in notches and overhangs.
Erosive forces include wave attack, sea-water spray, wind and rain.
They also support special plant
communities recognised for the maritime nature of the flora. These
communities include both calcareous grassland and heath. Because of the nature
of the conservation interest, which is normally associated with the presence
of species rich plant and animal communities only two states have been identified.
These are intimately bound up with the maintenance of open swards through exposure
and grazing (State
1) and the growth of coarse grassland and scrub in areas where grazing
is reduced or ceases altogether (State
2).
Caveat: These may provide sites for sometimes large numbers of nesting
seabirds. This aspect of their value is not dealt with in this guide.
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