Ares Valles

This image from NASA Mars Odyssey covers a portion of Ares Valles, an outflow channel carved into the surface of Mars by ancient catastrophic floods. The floods were most likely caused by huge discharges of groundwater at the channel heads. These floods are similar to (but much larger than) floods that created the Channeled Scablands in central Washington State during the last ice age on Earth. The Martian channels are hundreds of kilometers long and occur in a number of regions within equatorial Mars. The material that was eroded away by these floods was deposited as sediment in the northern lowlands. The Mars Pathfinder landing site is several hundred kilometers downstream from the location of this image and the surfaces are probably similar in nature. http://photojournal.jpl.nasa.gov/catalog/PIA04026