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
Elizabeth Reef Elizabeth Reef Elizabeth Reef is a coral reef in the Tasman Sea. The reef is separated by a deep oceanic pass, some 45 km wide, from nearby Middleton Reef, both of which are part of the underwater plateau known as the Lord Howe Rise. It is around 160 km from Lord Howe Island and 555 km from the New South Wales coast of Australia. The Environment, Sport and Territories Legislation Amendment Act 1997 included Elizabeth Reef in Australia's Coral Sea Islands Territory. It is the southernmost coral atoll in the world and one of the southernmost platform reefs in the