Great Barrier Reef

About 500 million years ago, the world's first coral reef occurred and the first close relatives of modern corals developed in southern Europe about 230 million years ago. 



This series of small reefs formed underwater and can be made of corals, stone, or rock. Below sea level, the top of the reef are lying. This coral reefs are normally found in warm, shallow, clean water. Nowhere can be found as larger as The Great Barrier Reef in the world, stretching an amazing 1,250 miles, or 2,000 kilometers, rest across the blue of the ocean. Between the strong waves of the Pacific and the coast of Australia, it forms a natural break water. This was located in the Coral Sea, the area of the Pacific close to Australia's northeastern coast. The waters around it cover roughly 80,000 square miles, or 208,000 kilometers, an area slightly smaller than the state of Minnesota.

You can find reefs as deep as 250 feet below the surface. Below 150 feet, corals grew here don't make very good reef builders.
 Reefs are classified into three different groups. The first reef type is called a Fringing reef. This reef is formed as coral grows in the shallow waters along the shores of land. A barrier reef, such as the Great Barrier reef, grows some distance from the shore before coming close to the surface. A lagoon separates the barrier reef from the shore. An Atoll reef is a circular reef, usually with a lagoon in the center. The waves of the lagoon cover a submerged island. The reef grows in layers over the island.

Islands on the Great Barrier reef are considerable in number made of coral sand that has piled up to make islands. Coral sand is formed when waves constantly wash over the dead coral, breaking it in to sand. These islands have been given the name Coral Cays. This Coral Cays are impossible to reach by boat. They are hard to see, and the sharp coral can possibly tear out the bottom of a boat. You can still be found an ancient shipwreck among the coral!
Reefs as large as the Great Barrier Reef take thousands of years to develop. If you happen to visit a reef, any reef, be careful to not step on living coral. Most grow slowly, maybe less than two inches, or five centimeters a year. It would take years to replace it, and developed!