Stage 1 Corals settle and grow on the slopes of the new volcanic island. At first, the coral reef is near shore.A young volcanic island has rounded cliffs, older ones have jagged cliffs because of erosion.

Stage 2 Many years later the island "sinks" because of heavy erosion and it has more coral reefs around what's left of the volcanic island.

Stage 3 As the volcanic island erodes and the sea floor slowly sinks, the distance between the shore and the coral reef increases. If the sea floor sinks slowly enough, the coral reef keeps growing near the surface. When the volcanic island dives under the ocean, what's left of the volcanic island is covered by coral reef. That's when its called an atoll.

Stage 4

If the sea floor sinks too quickly, or as the Pacific plate moves the atoll into colder water, the coral reef dies and the atoll is washed away by wind and waves. Only a guyot remains.

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