The second stage is barrier reef forms. A barrier reef forms when the oceanic island sinks into Earth’s crust because of the lacking of volcanic island building forces, the additional weight of the coral reef and the disintegration at the surface of the island. As the island sinks, the coral reef keeps on growing upward. The coral creatures lay down colossal amounts of calcium carbonate as their skeletons. They can keep pace with the sinking island for the most part if conditions are great. Their living tissue stays in the upper part of the reef in the warm, clear and tropical water. The lower portion of the reef is made up of the calcium carbonate skeletons left by the reef building coral. This upward development makes a lagoon of water
