Transcript Beagle

Reef growth stage:
1. Fringing reef
2. Barrier reef
3. Atoll
Fringing reef - Kosrae, Federated States of Micronesia
Fringing reef - Moorea, French Polynesia
Fringing transition to barrier reef - Moorea, French Polynesia
Barrier reef - Pohnpei, Federated States of Micronesia
Shelf barrier reef - Belize
Barrier to Atoll transition Chuuk (Truk Lagoon),
Federated States of Micronesia
Remnant volcanic island - Chuuk, Federated States of Micronesia
Tern Island at French Frigate Shoals
Atoll rim islands - Majuro, Republic of the Marshall Islands
Atoll rim airport - Republic of the Marshall Islands
Oroluk Atoll, Federated States of Micronesia
Fanning Island, Kiribati
Transition from fringing reef to barrier reef according to
Charles Darwin following his voyage on the HMS Beagle
1831-1836 – it ain’t new.
Transition from barrier reef to atoll (after Charles Darwin).
Cross-sectional structure of a typical atoll. Enewetak and Midway
have both been drilled to volcanic basement confirming their origins.
So – Seamounts, Fringing Reefs, Barrier Reefs, Atolls,
and Guyots are all linked – they are all part of the
on-going tectonic activity associated with the oceans.
Where do submarine canyons fit in?
What is a Seamount? What is a Guyot? In relation to
Islands, reefs and atolls
Seamount = the starting point for reefs and atolls
Guyot = an end-point, a flat-topped seamount, many about 1300 m
underwater in the Pacific, topped by old coral reefs –
erosion, subsidence, and sea level rise