Seismic experiment gives best evidence yet for mantle plumes. Geologists have obtained the best image yet of a plume of hot rock that rises from Earth's deep mantle and fuels the volcanoes of the Hawaiian islands. The study, led by geophysicist Cecily Wolfe at the University of Hawaii at Manoa in Honolulu, reveals the structure of the plume down to at least 1,500 kilometres. Critics have questioned in recent years whether such plumes even exist. "This is a spectacular experiment that succeeded in getting data for putting the plume theory to the test," says Wolfe. The results are published this...