How the GBR Was Formed

How did the Great Barrier Reef form?

It is believed that 1.2 million years ago, there was a harsh change in climatie conditions. When the polar ice caps started to melt, the sea levels rose. Old records show that the sea level rose and feel up to 24 times. Because of this Australia's continental shelf flooded so the corals hept pace with the rising sea levels and they started growing on the edges of these shelves. This is what formed the Great Barrier Reef.

Marine geoscientists discovered that it would of taken a reef the size of the Great Barrier Reef somewhere between 50,000 and 100,000 years to form. It was formed by a series of 3000 idividual reefs and 100 islands. The reef is home to approximately 400 species of coral, 2000 diiferent varieties of fish, and until today 4000 species of mollusks have been identified.

What did the Great Barrier Reef need to form?

The reef required a certain amount of sunlight and they will only grow in shallow, clean water. There are three substances that a reef is made up of and they are - sand, rock or coral. The temperature for a reef to form must be between 18 degrees Celsius and 30 degrees Celsius. 
The sea animals called polyps form colonies that make the reefs, this animal has many tentacles around its mouth. Many polyps join together to form a colony. The Barrier Reef is made of many coral reefs. Reefs including the Great Barrier Reef are formed due to the association between a sea animal and a single-celled plant.