■ ATOLL #coralreefs ◇ A ring of narrow growing corals of ho | Upsc geography
■ ATOLL
#coralreefs
◇ A ring of narrow growing corals of horseshoe shape and crowned with palm trees is called atoll. It is generally found around an island or in elliptical form on a submarine platform.
◇ Atolls are divided into 3 types. E.g. (i) true atoll characterized by circular reef enclosing a shallow lagoon but without island, (ii) island atoll having an island in the central part of the lagoon enclosed by circular reef, and (iii) coral island or atoll island does not have island in the beginning but later on island is formed due to erosion and deposition by marine waves.
◇ Shallow lagoon reefs are minor reef features which are annular in shape and are found in epi-continental seas like Indonesian Sea, South China Sea etc. The lagoon is a small pool. Faros are chains of small atolls having shallow small lagoons. Coral banks are isolated shapeless reefs. Coral pinnacles are small ridges which rise within the lagoons.
