The Grand Canyon is nearly 300 miles long and over a mile deep. You could stack four Empire State buildings one on top of the other and they still wouldn't reach the lip of the Canyon. As vast tectonic plates clash and grind against one another a giant plateau has been pushed up over a mile in the air. The Colorado river, flowing from high in the Rockies and carrying a thick load of sediment, has carved an amazing canyon in the rising plateau.
