coral atoll
Lagoon-encircling reef formation
A coral atoll is a ring-shaped island or chain of islands formed from coral reef, encircling a central lagoon.
Atolls develop over millions of years as coral grows around a volcanic island that eventually subsides beneath the sea, leaving the reef structure behind.
They occur mainly in tropical Pacific and Indian Ocean waters: The Maldives consist almost entirely of coral atolls.
- barrier reefOffshore coral formation
- lagoonSheltered coastal shallows
- subsidenceGradual ground sinking
- MaldivesIndian Ocean archipelago nation
- sea level riseIncreasing ocean surface height
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coral atollvolcanic island
Land formed by eruptions
volcanic peak · stratovolcano · shield volcano · volcanic cone · seamount
coral atollmountain peak
Topmost point of elevation
volcanic cone · volcanic peak · alpine peak · Mauna Kea · Mount Everest