Wave-cut platform

Wave-cut platform
Wave-cut platform. In this case, alternating hard and soft layers have been folded up vertically and eroded by the tides, resulting in a regular ripple pattern at the surface.

A wave-cut platform, or shore platform is the narrow flat area often found at the base of a sea cliff or along the shoreline of a lake, bay, or sea that was created by the action of waves. Wave-cut platforms are often most obvious at low tide when they become visible as huge areas of flat rock. Sometimes the landward side of the platform is covered by sand, forming the beach, and then the platform can only be identified at low tides or when storms move the sand.

Contents

Formation

The formation of a wave cut platform

It forms after destructive waves hit against the cliff face, causing undercutting between the high and low water marks, mainly as a result of corrasion and hydraulic power, creating a wave-cut notch. This notch then enlarges into a cave. The waves undermine this portion until the roof of the cave cannot hold due to the pressure and freeze-thaw weathering acting on it, and collapses, resulting in the cliff retreating landward. The base of the cave forms the wave-cut platform as attrition causes the collapsed material to be broken down into smaller pieces, while some cliff material may be washed into the sea. This may be deposited at the end of the platform, forming an off-shore terrace.

Because of the continual wave action, a wave-cut platform represents an extremely hostile environment and only the toughest of organisms can utilize such a niche.

Use of ancient examples

Ancient wave-cut platforms provide evidence of past sea and lake levels. Raised and abandoned platforms, sometimes found behind modern beaches, are evidence of higher sea levels in the geological past,[1] and have been used to identify areas of isostatic adjustment. By using scientific dating methods, or examination of marine fossils found on the platform, it is possible to work out when the platform was formed, thus giving geographers and geologists information about sea levels at known times in the past. This has been used in the United Kingdom and other previously glaciated areas to calculate the rate at which land is rising now that it is no longer covered in ice.

Where the coastline itself is changing due to seismic action, there may be a series of platforms showing earlier sea levels and indicating the amount of uplift caused by various earthquakes.

Usage of term 'wave-cut'

According to Trenhaile [2] and Sunamura,[3] "the term 'Wave Cut Platform' should no longer be used as it assumes that shore platforms are the result of wave action, which is not always true. Shore Platforms are clearly erosional features that develop when erosion of a rocky coast and the subsequent removal of the debris by waves and currents leave behind the erosional surface".[4]

References

  1. ^ Wilson, M.A., Curran, H.A. and White, B. 1998: Paleontological evidence of a brief global sea-level event during the last interglacial. Lethaia 31: 241-250.[1]
  2. ^ Trenhaile, A. S. 1987: The Geomorphology of Rock Coasts. (Oxford University Press, Oxford, U.K.) 393 pp.
  3. ^ Sunamura, T., 1992. Geomorphology of rocky coasts. New York: John Wiley.
  4. ^ Masselink, G and Hughes, M. 2003. Introduction to Coastal Processes and Geomorphology. Hodder Arnold

See also

v · d · eCoastal geography
Landforms Accreting coast Image6.svg

Fernando noronha.jpg
Beaches
Processes
Management
Related

Wikimedia Foundation. 2010.

Игры ⚽ Поможем сделать НИР

Look at other dictionaries:

  • wave-cut platform — ˌwave cut ˈplatform 7 [wave cut platform] noun (technical) an area of land between the ↑cliffs and the sea which is covered by water when the sea is at its highest level …   Useful english dictionary

  • wave-cut platform —    A gently sloping surface produced by wave erosion, extending into the sea or lake from the base of the wave cut cliff. This feature represents both the wave cut bench and the abrasion platform.    Compare: submerged wave cut platform.    GG …   Glossary of landform and geologic terms

  • wave-cut platform — or abrasion platform Gently sloping rock ledge that extends from the high tide level at a steep cliff base to below the low tide level. It develops as a result of wave abrasion; beaches protect the shore from abrasion and therefore prevent the… …   Universalium

  • wave-cut platform —   at a coast, where wave action erodes into a cliff, causing it to collapse and retreat, a rock platform is left behind between the low and high water marks …   Geography glossary

  • submerged wave-cut platform —    A subaqueous, relict erosional landform that originally formed as a wave cut bench and abrasion platform from coastal wave erosion and later submerged by rising sea level or subsiding land surface.    Compare: wave built terrace, wave cut… …   Glossary of landform and geologic terms

  • wave — waveless, adj. wavelessly, adv. wavingly, adv. wavelike, adj. /wayv/, n., v., waved, waving. n. 1. a disturbance on the surface of a liquid body, as the sea or a lake, in the form of a moving ridge or swell. 2. any surging or progressing movement …   Universalium

  • Wave — /wayv/, n. a member of the Waves. Also, WAVE. [1942; see WAVES] * * * I In oceanography, a ridge or swell on the surface of a body of water, normally having a forward motion distinct from the motions of the particles that compose it. Ocean waves… …   Universalium

  • platform — platformless, adj. /plat fawrm/, n. 1. a horizontal surface or structure with a horizontal surface raised above the level of the surrounding area. 2. a raised flooring or other horizontal surface, such as, in a hall or meeting place, a stage for… …   Universalium

  • wave-built terrace —    A gently sloping coastal feature at the seaward or lakeward edge of a wave cut platform, constructed by sediment brought by rivers or drifted along the shore or across the platform and deposited in the deeper water beyond.    Compare:… …   Glossary of landform and geologic terms

  • submerged wave-built terrace —    A subaqueous, relict depositional landform originally constructed by river or longshore sediment deposits along the outer edge of a wave cut platform and later submerged by rising sea level or subsiding land surface.    Compare: wave built… …   Glossary of landform and geologic terms

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”