How Are Atolls Formed?


Atolls are formed first as a reef that fringes a volcanic island. As the island sinks after the volcanic activity has stopped and the Earth crust has cooled, the reef continues to build upward, finally ending up as a ring-shaped structure. These ring-shaped islands or arc of islands are made almost entirely out of coral.
About -  Privacy -  Careers -  Ask Blog -  Mobile -  Help -  Feedback  -  Sitemap  © 2014