Charles Darwin may not have been entirely correct about coral reefs. Darwin proposed that coral atolls were thousands of feet in a theory that he published in 1842, but many scientists have believed that they were a thin veneer of coral.
OurAmazingPlanet.com reported that"Coral reefs are actually huge colonies of tiny animals that need sunlight to grow. After seeing a reef encircling Moorea, near Tahiti, Darwin came up with his theory that coral atolls grow as reefs stretch toward sunlight while ocean islands slowly sink beneath the sea surface. (Cooling ocean crust, combined with the weight of massive islands, causes the islands to sink.)"
Deep drilling on reefs confirmed Darwin's theory in 1953.
However a new study published in the journal of Geology proves that reef-bulding is more complex than Darwin thought. A computer model found that sea levels which rise and fall with glacial cycles are the primary reason for the patterns.
"Darwin actually got it mostly right, which is pretty amazing," said Taylor Perron to OurAmazingPlanet, the study's co-author and a geologist at MIT.
He added that however, "He didn't know about these glacially induced sea-level cycles".
OurAmazingPlanet.com used Hawaii as an example.
"Coral grows slowly there, because the ocean is colder than in the tropics. When sea level is at its lowest, the Big Island builds up a nice little reef terrace, like a fringe of hair on a balding pate. But the volcano - one of the tallest mountains in the world, if measured from the seafloor - is also quickly sinking. Add the speedy sea-level rise when glaciers melt, and Hawaii's corals just can't keep up. The reefs drown each time sea level rises," they explained.
Perron added, "You can explain a lot of the variety you see just by combining these various processes - the sinking of islands, the growth of reefs, and the last few million years of sea level going up and down rather dramatically."
The computer model can account for coral reefs at islands around the world, while Darwin's model can't explain it.
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