Even great scientists like Charles Darwin sometimes get things wrong. New research indicates Darwin may have been wrong about how coral atolls evolve.
Coral atolls, ring-shaped reefs usually surrounding lagoons, were believed to have been created by the emergence, and subsequent retreat, of volcanoes from the sea. Darwin published his theory in his 1839 publication “The Voyage of the Beagle,” written during his trip from England to South America and Australia aboard the HMS Beagle.
A new report published in the journal Geology by researchers from the Massachusetts Institute of Technology reveal Darwin was partially wrong about how coral atolls evolve. Coral are living organisms, and while they do cling to lava and other debris surrounding a volcano as it emerges from the sea, changes in sea level are even more important in the development of the large colonies of coral that make up atolls.
The MIT researchers used computer models to test Darwin’s theory and discovered volcano emergence plays a smaller role in the growth of coral atolls and that many other formations do not follow Darwin’s theory. According to the study’s abstract, “Compiled data from modern systems show, however, that many islands do not follow this sequence, implying that reefs are shaped by more than island subsidence alone. We show that the diversity of modern reef morphology arises from the combined effects of island subsidence, coral growth and glacial sea-level cycles.”
While previous research has proved Darwin right about his theories about coral atoll formation, he was only partially right about their evolution. Speaking to OurAmazingPlanet, geologist Taylor Perron, the study’s co-author, said, “Darwin actually got it mostly right, which is pretty amazing.”
In Chapter 20 of “The Voyage of the Beagle,” written when Darwin was exploring the Keeling Islands, he remarks, “If then the foundations, whence the atoll-building corals sprang, were not formed of sediment, and if they were not lifted up to the required level, they must of necessity have subsided into it; and this at once solves the difficulty. For as mountain after mountain, and island after island, slowly sank beneath the water, fresh bases would be successively afforded for the growth of the corals.”
As volcanoes rose from the sea, coral and other living organisms soon clung onto the sides of the volcanoes and, as the volcanoes became dormant and sank back into the sea, the coral remained near the water’s surface, thus creating atolls.
Perron discusses Hawaii’s corals as one example where Darwin’s theory is inaccurate. The coral surrounding the Big Island, notes OurAmazingPlanet, does grow slowly, mostly due to colder ocean temperatures, but it soon gets swallowed up as sea levels rise.