Cliffs and islets
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"Cliffs and islets" is one of the habitat sub-categories dealing with biodiversity of coastal and marine habitats and ecosystems.
A cliff is defined in the Oxford English Dictionary as "a steep rock face, especially at the edge of the sea". Sea cliffs make up long stretches of coast defined as a break in slope between 15 degrees and the vertical, variable in height, found at the contact between the land and sea. They owe their existence in some way to erosion by the sea. Form and height depends on the type of rock - 'hard' rock (metamorphic, igneous and sedimentary rocks) and 'soft' rock (earth cliffs).
In the habitat classification used by the European Union  there are four types defined by the vegetation and their geographical location all considered to be composed of 'Hard' rock:
- 1230 Vegetated sea cliffs - Atlantic & Baltic, PAL.CLASS.: 18.21
- 1240 Vegetated sea cliffs - Mediterranean with endemic Limonium spp., PAL.CLASS.: 18.22
- 1250 Vegetated sea cliffs with endemic flora of the Macaronesian coasts, PAL.CLASS.: 18.23 and 18.24
- 4040 * Dry Atlantic coastal heaths with Erica vagans, PAL.CLASS.: 31.234
'Soft' rock sea cliffs are not classified although they can be considered to be included in 1230 above.
- Carter, R.W.G., 1988. Coastal Environments. An Introduction to the Physical, Ecological and Cultural Systems of Coastlines. Academic Press, London.
- European Commission, 2007. Interpretation Manual of European Habitats. Natura 2000. European Commission, DG Environment, Nature and Biodiversity, Brussels. Source: http://ec.europa.eu/environment/nature/legislation/habitatsdirective/docs/2007_07_im.pdf.
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