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The oldest Hawaiian Islands: How they evolved
The Northwestern Hawaiian islands once were like the main Hawaiian Islands we live on today, born of rising magma from the Earth's mantle. The islands moved northwest with the Pacific Plate, and erosion reduced them to islets and coral atolls. The oldest islands are farthest from the main Hawaiian chain. How an island evolves:
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1. A volcano erupts, forming an island. Over time erosion and sinking continue while fringing coral reef grows around the island.
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In this stage:
The eight main Hawaiian Islands
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2. Coral continues to grow around the shoreline as the island slowly erodes and sinks. Lagoons and barrier reefs are formed.
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In this stage:
Nihoa, Mokumanamana, Gardner Pinnacles
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3. As the island continues to sink, it disappears; a reef called an atoll, usually circular, forms over the submerged island.
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In this stage:
French Frigate Shoals, Kure, Pearl and Hermes, Midway, Laysan, Lisianski
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4. The atoll dies when water becomes too cold for growth. The coral-capped volcano continues to sink below sea level and becomes a seamount or a guyot. |
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In this stage:
Banks and seamounts in the chain
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