The Choreography of Continents
While John Rogers (University of North Carolina Chapel Hill) has found strong evidence for the existence of several ancient continents [the first being Ur], their exact shape and position are unknown. Most of the world's continental crust merged to become Rodinia about 1 billion years ago, and then became Pangea about 336 to 173 million years ago. When Pangea started to break up about 175 million years ago, the earlier continents dispersed, becoming part of today's continental masses.

images by Julia Bryan