Some 250 million years ago, at the beginning of the Secondary or Mesozoic era - the age of the large saurians - all the continents were grouped into a single supercontinent known as Pangaea. The Changing Face of the Earth shows the nine most important stages in the break-up of this supercontinent. Nine 'milestones' illustrate the paths along which the different continental blocks drifted to arrive at the geological face of the Earth, as we know it today.