Supercontinent formation and True Polar Wander

There have been several periods in the history of this planet when all the continents have united in a single supercontinent. The most recent occasion was the supercontinent Pangaea, which began to break up 175 million years ago with the formation of the proto-Atlantic Ocean.
Map of Pangaea

Not only do the continents move around relative to one another, the entire solid earth may shift with respect to the earth's axis of rotation: True Polar Wander (TPW). The article Absolute plate motions and true polar wander in the absence of hotspot tracks in Nature (2008) discusses the evidence for TPW at the time of the formation of Pangaea, 300 million years ago.

Supercontinent cycles and the calculation of absolute palaeolongitude in deep time, also in Nature(2012), outlines a far-reaching theory that tries to explain where and how a new supercontinent forms in relation to the previous supercontinent in the cycle. The next supercontinent is conjectured to be Amasia which may form due to the closing of the Arctic and Caribbean seas.