IT SEEMS an ancient supercontinent got peckish and ate part of itself.
Supercontinents form when all of the world’s landmasses join together. The most recent, Pangaea, was shaped like a pie with a piece missing, and the Palaeotethys ocean filled the gap.
Gabriel Gutiérrez-Alonso of the University of Salamanca in Spain and colleagues reckon that when this ocean partially closed around 200 million years ago, a portion of the continental crust beneath the ocean slipped under another portion, in a process new to plate tectonics.
The crunching and stretching that followed, they say, explains rift valleys and an ancient…
