Darwin's Atolls Theory Challenged
Though his theory of evolution may be holding up, Charles Darwin's well-regarded theory of how ring-shaped islands called atolls formed in tropical oceans is getting some serious revising, a University of Arizona geologist said. William Dickinson believes that sea-level changes and erosion played big roles—and these, in turn had a big implications for how and when Polynesians spread through the South Pacific.
Darwin's atoll theory isn't really being challenged; this is more of an update. Darwin's theory that atolls are formed by coral growning on top of submerging volcanos is still basically correct.