Lethe Vallis

Lethe Vallis is a valley in the Elysium quadrangle of Mars, located at 4° North and 206.5° West. It is 225 km long and is named after a river in Katmai National Monument, Alaska, USA. Lethe Vallis originates at the SE margin of the West Elysium Basin. West Elysium Basin probably contained a lake that was 500 km across and received water from Athabasca Vallis. It was probably formed in just days or weeks and had a discharge about like the Mississippi. Some have suggested it was formed from lava flows, but lava would not be able to flow over such a low gradient for so long a distance.