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Darwin's coral atoll: geomorphology and recent development of the Cocos (Keeling) Islands, Indian Ocean

Journal Article


Abstract


  • The Cocos (Keeling) Islands in the eastern Indian Ocean, the only coral atoll that Charles Darwin ever visited, became central to theories on the development of atolls. The authors have reexamined the reef islands on Cocos, and have undertaken shallow drilling through the conglomerate platform composed of cemented coral boulders and shingle that underlies each of the islands. Radiometric dating of coral indicates rapid vertical accumulation of the reef during the early to mid Holocene as sea level rose, and subsequent reef-top consolidation during the late Holocene under relatively stable sea-level conditions. The conglomerate platform formed 4000 to 3000 years ago as a former reef flat when sea level was at least 50 cm above present with respect to the atoll. Home Island, one of the reef islands, has formed in the last 3000 years. -from Authors

Publication Date


  • 1990

Citation


  • Woodroffe, C., McLean, R., & Wallensky, E. (1990). Darwin's coral atoll: geomorphology and recent development of the Cocos (Keeling) Islands, Indian Ocean. National Geographic Research, 6(3), 262-275.

Scopus Eid


  • 2-s2.0-0025622409

Start Page


  • 262

End Page


  • 275

Volume


  • 6

Issue


  • 3

Abstract


  • The Cocos (Keeling) Islands in the eastern Indian Ocean, the only coral atoll that Charles Darwin ever visited, became central to theories on the development of atolls. The authors have reexamined the reef islands on Cocos, and have undertaken shallow drilling through the conglomerate platform composed of cemented coral boulders and shingle that underlies each of the islands. Radiometric dating of coral indicates rapid vertical accumulation of the reef during the early to mid Holocene as sea level rose, and subsequent reef-top consolidation during the late Holocene under relatively stable sea-level conditions. The conglomerate platform formed 4000 to 3000 years ago as a former reef flat when sea level was at least 50 cm above present with respect to the atoll. Home Island, one of the reef islands, has formed in the last 3000 years. -from Authors

Publication Date


  • 1990

Citation


  • Woodroffe, C., McLean, R., & Wallensky, E. (1990). Darwin's coral atoll: geomorphology and recent development of the Cocos (Keeling) Islands, Indian Ocean. National Geographic Research, 6(3), 262-275.

Scopus Eid


  • 2-s2.0-0025622409

Start Page


  • 262

End Page


  • 275

Volume


  • 6

Issue


  • 3