Reef growth stage 1 Fringing reef 2 Barrier

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