A raised coral atoll or uplifted coral atoll is an

atoll An atoll () is a ring-shaped island, including a coral rim that encircles a lagoon partially or completely. There may be coral islands or cays on the rim. Atolls are located in warm tropical or subtropical oceans and seas where corals can gr ...

that has been lifted high enough above sea level by

tectonic Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents ...

forces to protect it from scouring by storms and enable soils and diverse – often

endemic Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...

– species of flora and fauna to develop. With the exception of Aldabra Island in the

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...

and Henderson Island in the

Pacific Ocean The Pacific Ocean is the largest and deepest of Earth's five oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean (or, depending on definition, to Antarctica) in the south, and is bounded by the continen ...

, most tropical raised atolls have been dramatically altered by human activities such as species introduction, phosphate mining, and even bomb testing.Fosberg FR, Sachet MH, Stoddart DR (1983)
Henderson Island (Southeastern Polynesia): summary of current knowledge.
''Atoll Research Bulletin'' 272: 1–47.

References

Atolls Coastal and oceanic landforms Coral islands {{Marine-geo-stub