atoll

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Diagram showing the stages of atoll formation: a volcanic island forms above a mantle plume, then gradually sinks to become a sinking island, guyot, barrier reef, and eventually an atoll or seamount, with cross-sections illustrating magma movement, oceanic crust, and plate tectonics.

A three-part diagram shows the formation of a coral atoll: first, a volcanic island with a surrounding coral reef; next, the island sinks as the coral reef grows upward; finally, the island disappears below the surface, leaving a ring-shaped atoll of coral with a central lagoon. Both top and side views are provided for each stage.

At a Glance

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atoll: Media

coral reef

Images

Diagram showing the stages of atoll formation: a volcanic island forms above a mantle plume, then gradually sinks to become a sinking island, guyot, barrier reef, and eventually an atoll or seamount, with cross-sections illustrating magma movement, oceanic crust, and plate tectonics.

atoll formation

Diagram depicting the process of atoll formation. Atolls are formed from the remnant...

Encyclopædia Britannica, Inc.

Pukapuka Atoll

Pukapuka Atoll

Aerial view of Pukapuka Atoll.

Ewan Smith

A three-part diagram shows the formation of a coral atoll: first, a volcanic island with a surrounding coral reef; next, the island sinks as the coral reef grows upward; finally, the island disappears below the surface, leaving a ring-shaped atoll of coral with a central lagoon. Both top and side views are provided for each stage.

atoll formation

Formation of an atoll.

Encyclopædia Britannica, Inc.

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