Signs of Water
Canals and Channels
East
of Tharsis and south of the equator lies a system of canyons known as the Valles
Marineris. It begins at the summit of the Tharsis bulge and extend 4,000 km
eastwards into chaotic terrain. Depths range from 2 km to over 7 km where three canyons
merge and form a 600 km chasm. In some parts of the canyons there is layered
sediments. They might have formed under water, so many geologists believe that
standing bodies of water partly filled these canyons in the past, though they might have
also been created by seasonal changes in the Martian climate. It is also believed
that flows created these channels, strong ones that may have been up to 10,000 times the
average discharge rate of the Mississippi River. Impact craters are scarce within
the Valles Marineris, probably because of erosion and deposition by landslides and wind.
There are thousands of outflow channels that connect with the Valles Marineris that
can be 100 km wide and 2000 km long that make up the chaotic terrain. They were
probably formed by floods of water released from large groundwater reservoirs. As
the water flowed across the land, it would simultaneously freeze and evaporate.