how are coral islands formed?
Answers
Explanation:
A coral island is a type of island formed from coral detritus and associated organic material.They occur in tropical and sub-tropical areas, typically as part of coral reefs which have grown to cover a far larger area under the sea.
Coral islands are low islands formed in warm waters by tiny sea animals called corals. Corals build up hard external skeletons of calcium carbonate. This material, also known as limestone, is similar to the shells of sea creatures like clams and mussels. Colonies of corals may form huge reefs.
Main Part:-
Coral islands begin as a volcanic island over a hot spot. As the volcano emerges from the sea a fringing reef grows on the outskirt of the volcano. The volcano eventually moves off of the hot spot through a process known as plate tectonics. Once this occurs the volcano can no longer keep up with the erosion that is taking place due to the ocean and undergoes subsidence.
Once the island is submerged the coral must keep growing to stay in the epipelagic zone (sunlit). This causes the coral to grow into an atoll with a shallow lagoon in the middle. The lagoon can then undergo accretion and create an island completely made of carbonate materials. The process is later enhanced with the remains of plant life which grows on the island.[3]
When the living polyps die , their skeletons are left . other polyps grow on top of the hard skeletons which grows higher and higher, thus , forming the coral islands .