RODINIA
The Rodinia supercontinent formed approximately 1 Ga (billion years ago) due to the subduction of ocean basins followed by a series of continental collisions. The Rodinia supercontinent, situated about the South Pole, is thought to have persisted over 250 million years. Supercontinent rifting and breakup occurred approximately 725 Ma, producing new ocean basins (e.g. Panthalassic Ocean) and rift faults such as the Reelfoot Rift, which extends from the Gulf of Mexico to Illinios. The active New Madrid earthquake zone in Missouri occurs along the Reelfoot Rift.
Global projections of Earth from 750 Ma to present located at: http://www.uwgb.edu/dutchs/platetec/plhist94.htm
Global projections of Earth at 650 Ma located at: http://www.scotese.com/precambr.htm