Lethe Vallis, as seen by HiRISE. Flow was from southwest to northeast. Wider part of Lethe Vallis had less erosive power, so mesas are left behind from pre-existing material. Scale bar is 500 meters long.
Lethe Vallis is a valley in the Elysium Planitia on Mars, located at 4° North and 206.5° West. It is 225 km long and is named after river Lethe in Katmai National Monument, Alaska, USA.[1] Lethe Vallis originates at the SE margin of the West Elysium Basin (Cerberus Palus). 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.[2]
References
^"Lethe Vallis". Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program.
.jpg){kind=small}