According to the theory of continental drift, in prehistoric times, many of today' s separate continents were part of a single huge landmass  As the plates on which this landmass rested began to move, the mass broke apart, and ocean water filled the newly created chasms
A large band of ancient rock of a rare type along the east coast of South America is of the same type as a band on the west coast of Africa.
 It is hypothesized, for example, that South America was once joined on its east coast with what is now the west coast of Africa