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Both cliffs and rocks
For those organisms inhabiting beaches, particle
size of the beach material is important. Beaches can be composed of anything
from very small clay and mud particles
to enormous blocks, boulders and cliffs. Particle composition is dependent
of two factors:
The areas geological history, for example plate tectonics
and glacial effects are of importance for the type of material and its
distribution.
Those water movements the shoreline is exposed to in the form
of currents and waves.
Because movements of water wash away the finest particles,
they can only be found in the most wave protected areas. Cliffs on the
other hand, can be found in both wave protected and exposed areas. Wave
effect is greatest at the surface, even if there are cliffs higher up
the beach, there are usually rocks and finer particles further down.
Quite often you can find identical organisms on rocky and
peeble beaches as you would amongst cliffs, but these beaches usually
have a richer fauna, because of the nooks and crannies amongst the rocks
create countless micro-environments. All the cavities give protection
and conditions vary greatly. Furthermore, rocks and peebles can be held
together in place by sand, remains of algae and floatsom.
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