Hidden crystals offer clue to a geological riddle

A South African scientist believes that zircons found on Mauritius may be the remants of a buried continental fragment

Oceanic crust lives fast and dies young, usually being dragged down a subduction zone after 250m years or so. By contrast, continental crust lives to a ripe old age, with some of the oldest continental crust on Earth - dating to 4bn years - found in Canada and Greenland.

But geologists have long been puzzled as to why there isn't more continental crust bobbing around. Now new research indicates that some of it might be hidden underneath ocean-island volcanoes.