According to Charles Darwin's subsidence model, [5] the formation of an atoll is explained by the sinking of a volcanic island around which a coral fringing reef has formed. Over geologic time, the volcanic island becomes extinct and eroded as it subsides …

atoll, coral reef enclosing a lagoon. Atolls consist of ribbons of reef that may not always be circular but whose broad configuration is a closed shape up to dozens of kilometres across, enclosing a lagoon that may be approximately 50 metres (160 feet) deep or more.

This animation shows the dynamic process of how a coral atoll forms. Corals (represented in tan and purple) begin to settle and grow around an oceanic island forming a fringing reef. It can take as long as 10,000 years for a fringing reef to form.

2023年10月19日 · An atoll is a ring-shaped coral reef, island, or series of islets. An atoll surrounds a body of water called a lagoon. Sometimes, atolls and lagoons protect a central island. Channels between islets connect a lagoon to the open ocean or sea. Atolls develop with underwater volcanoes, called seamounts. First, the volcano erupts, piling up lava on ...

Coral reefs begin to form when free-swimming coral larvae attach to submerged rocks or other hard surfaces along the edges of islands or continents. As the corals grow and expand, reefs take on one of three major characteristic structures—fringing, barrier, or atoll.

What is an “atoll”? For reef scientists, atolls are broadly defined as a large, ring-shaped coral reefs that surround a central lagoon. Coming up with a more specific and unambiguous definition of such reef formations is not all that easy however.

2017年6月9日 · As geography buffs know, ring-shaped coral reefs, islands, or groups of islets surrounding a central lagoon are known as atolls. The formation of an atoll is a slow process that can take millions of years. It begins when an underwater volcano erupts, creating a buildup of lava on the seafloor.

2024年2月23日 · 4. Atoll Formation. Eventually, the central island disappears completely beneath the ocean’s surface, leaving behind a ring of growing coral that marks the island’s former location. This ring of coral forms a barrier reef enclosing a central lagoon. The result is an atoll, a circular or horseshoe-shaped coral reef that encircles a lagoon ...

Darwin's theory set out a sequence of coral reef formation around an extinct volcanic island, becoming an atoll as the island and ocean floor subsided. When the Beagle set out in 1831, the formation of coral atolls was a scientific puzzle.

2024年12月5日 · For centuries, scientists have studied how atolls form, with notable contributions from Charles Darwin, James Dwight Dana, John Murray, and Reginald Daly. Each theorist proposed mechanisms that consider geological, biological, and climatic factors.