The network of gorges, valleys and parallel fractures etched in the surface of Mars known as the Valles Marineris could easily swallow the Grand Canyon in one of its smaller tributaries and dwarf the Great Rift Valley of Africa. The Valles Marineris, named for the Mariner probe that discovered the canyon, indicates that Mars once had its own equivalent of Earthly plate tectonics where the crust shifted and split open. But while the Earth's crust is fragmented into over two dozen plates that float on a hot thick layer in the mantle, Mars has just one crustal plate and a cold, thick, rigid surface.
Like Earth's canyons, however, the great Martian canyon that began as a crustal crack was carved deeper, wider and longer by wind erosion - so long, in fact, that the Valles Marineris could stretch across the continental United States from coast to coast.
While Mars may be very different from the planet that gives us life, features like the Valles Marineris inspire new curiosity in the red planet and remind us of the place of our blue one in the scheme of the universe.
