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12.8: Coral Reefs, Keys, and Atolls

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    Coral Reefs, Keys, and Atolls

    Biogenous carbonate sediments can accumulate faster than sea level is rising. Skeletal reefs (including coral reefs) thrive in the surf zone, and are able to weather wave action, although they can be heavily damaged by superstorm wave energy. The sediments generated by wave erosion and bioerosion (critters eating critters) contribute to the buildup of carbonate islands (keys) and atolls associated with fringing reefs forming around extinct and eroding volcanic islands (Figures 12-31 to 11-33). Keys and reefs of the world experience exposure and erosion during low sea levels during the ice ages.

    Carbonate depostional environments Coral reefs and keys on an atoll in the Marshall Islands. Mataiva Atoll
    Figure 12.31. Landforms associated with carbonate depositional environments. Figure 12.32. Coral reefs and keys, Kwajalein Atoll, Marshall Islands, South Pacific Ocean Figure 12.33. Mataiva Atoll, Tuamotu Archipelago, South Pacific Ocean

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