Can anyone explain how coral islands are formed and how long it takes to be formed?
Coral islands, or coral reefs, are the product of living organisms. Before the ecosystem that forms the reef, and later the island exists there must first be the right physical conditions for coral and other reef-dwellers to live. Coral must have shallow water, with high oxygen content. For this reason coral communities thrive best on windward locations where they will get lots of wave action both to oxygenate the water and to circulate and remove sediments. This same circulation brings food to the tiny polyps that catch food by filtering it, and that build the coral. One type of coral reef that forms beautiful rings with interior lagoons are those that are built on seamounts. These inactive volcanoes often subside slowly over time as they cool down. The coral will build upward at the same rate keeping up with sea level in most cases. If the coral does not grow upward fast enough to keep up, it will eventually die off from lack of food. This is often referred to as ‘drowning’ but is in
