Coral reef A fringing reef forms around an extinct volcanic island as the island and ocean floor subsides. As the subsidence continues, the fringing reef becomes a barrier reef and ultimately an atoll reef. Darwin predicted that underneath each lagoon would be a bedrock base, the remains of the original volcano. Subsequent research supported this hypothesis. Darwin's theory followed from his understanding that coral polyps thrive in the tropics where the water is agitated, but can only live within a limited depth range, starting just below low tide. Where the level of the underlying earth allows, the corals grow around the coast
Middleton Reef Middleton Reef Middleton Reef is a coral reef in the Tasman Sea. It is separated by a deep oceanic pass some 45 km wide from nearby Chan Reef, forming part of the Lord Howe Rise underwater plateau. It is around 220 km from Lord Howe Island and 555 km from the coast of New South Wales. In 1997 the Environment, Sport and Territories Legislation Amendment Bill 1996 included the reef in Australia's Coral Sea Islands Territory. It is among the southernmost platform reefs in the world. Despite its relatively high latitude, there is a wide variety of flora and fauna