A PRIZED POSSESSION in my office desk is an old flip book assembled in 1979 by Chris Scotese (then a graduate student, now a world authority on Earth’s ever-changing geography). Each page shows the positions of continents at a given time, and when you flip through the book rapidly, landmasses appear to move, as in an early stop-action movie. Every few seconds, words like “crash,” “crunch,” and “rrri-ppp” flash by, highlighting continental collisions and breakup.
