They say the layered earth rose up
Ancient rock leviathan
Trailing ages in its wake
Lifting earthness toward the sun
And coursing water cut the rock away
To leave these many-storied walls
Expose' of ages gone
Around this breathless emptiness
More wondrous far than earth had ever known.
-"Grand Canyon", Parker J. Palmer
If you've ever peered over the edge of the Grand Canyon of Arizona-or even looked down into much shallower, tree-covered river gorges of the northeastern U.S.-you may have wondered how Mother Nature carved such masterpieces of native rock. The action of running water coupled, in the case of Vermont's Quechee Gorge and New York's Ausable Chasm, with post-glacial rebounding of the land helped form canyons of varying size and magnificence.
On the red planet Mars, Mother Nature's electric carving knife was especially active.
The Mariner Valley, also known as the Valles Marineris canyon system, dwarfs even Earth's mighty Grand Canyon.
The Mariner is a huge gash across Mars and is some 2,500 miles long and a staggering four miles deep. By comparison,the Earth's Grand Canyon is a mere 500 miles long and only one mile deep. The Mariner is the grandest canyon of all the nine worlds of our solar system!
The Mariner canyon was formed by both tectonic activity and running water over billions of years. Looking at space images taken by several NASA Mars orbiters, you can see huge, ancient dry river channels that begin in nearby chaotic terrain, then through other north-central canyons, then head due north. Many of the channels also flowed into the mighty Acidalia Planitia basin, which is north of the Mariner Valley. Three giants volcanoes stand guard to the west of the Mariner. South of this canyon is more ancient terrain covered with thousands of meteor impact craters.
The Mariner Valley resembles rift valleys seen on Earth such as the East African Rift Valley.
There are other canyons on Mars, too. Loire Valles is an almost twin of the Grand Canyon of Arizona. It is about 440 miles long and the bottom channel expands from a half mile to about three miles wide. Numerous tributaries feed this canyon and the valley's northern escarpments are exactly like those seen at the Grand Canyon.
Lou Varricchio, M.Sc., is a former NASA science writer. He is the NASA/JPL Solar System Ambassador in Vermont and a senior member of the Civil Air Patrol, a U.S. Air Force auxiliary.