ATOLL
it is an island of coral that encircles a lagoon partially or completely. the word atoll is derived from the Dhivehi an Indo-Aryan language spoken on the Maldives islands word atholhu. its first recorded use in english was in 1625. the term was popularized by charles darwin who described atolls as a subset in a special class of islands.
DEFINITION :
atolls are those as " an annular reef enclosing a lagoon in which there are no promontories other than reefs & islet composed of reef detritus". these are the product of the growth of tropical marine organisms, so these islands are only found in warm tropical waters . volcanic islands located beyond the warm water temperature requirements of reef building organism become sea-mounts as they subside & are eroded away at the surface. islands more polar evolve towards sea-mounts islands more equatorial evolve towards atolls. most of the world's atoll are in PAcific ocean & Indian ocean.
LARGEST ATOLLS BY TOTAL AREA :
- saya de masha bank, western indian ocean 35,000 km2 without seperate north bank, submerged ; least depth 7m
- great chagos bank 12,642 km2 land by area only 4.5 km2
- reed bank, spratly islands 8860 km2, depth 9m
- macclesfield bank, south china sea 6448 km2, depth 9.2m
- north bank 5800 km2, depth <10m
- caysal bank, bahamas 5226.73 km2
- landsdocone bank, west of new caledonia 5000 km2, depth 3.7m
- thilaanunmathi-miladhumadulu atoll, maldives 3850 km2
- huvadhu atoll, maldives 3152 km2
- trunk lagoon , chuuk 3130 km2
- kepulauan sabalana, indonesia 2694 km2
- ishou reef, coral sea 2529 km2
- bassa de pedro 2474,33 km2, depth 16.4m
- ardasier bank, spratly islands 2347 km2
- kwajalein, marshall islands 2304 km2
- diamond islets bank, coral sea 2282 km2
- namonuito atoll, chuuk 2267 km2
- ari atoll, maldives 2252 km2
- maro reef, north-western hawaiian islands 1934 km2
- rangiroa tuamatu islands, 1762 km2
- kolhumadulu atoll, maldives 1617 mk2
- north male, maldives 1656 km2
- ontong java, solomon islands 1010
Atoll!
Linear Mode
