Ma'adim Vallis is one of the largest outflow channels on Mars. It is about 700 km long which is significantly larger than Earth's Grand Canyon. It is over 20 km wide and 2 km deep in some places. It runs from a region of southern lowlands thought to have once contained a large group of lakes (Eridania Lake) north to Gusev Crater.     Because it appears that water may have collected in Gusev Crater, forming a giant lake, the Spirit Rover was sent there to investigate that possibility. However, only volcanic rocks were found on the floor of Gusev. Any lake deposits were probably covered over by a later deposit of volcanic materials from Apollinaris Mons, a nearby volcano, just to the north.
Ma'adim Vallis is thought to have been carved by flowing water early in Mars' history.
- Cabrol, N. and E. Grin (eds.). 2010. Lakes on Mars. Elsevier. NY.
- Rossman, R.; et al. (2002). "A large paleolake basin at the head of Ma'adim Vallis, Mars". Science. 296: 2209–2212.
- HiRISE | Chaos in Eridania Basin (ESP_037142_1430)". Uahirise.org. 2014-09-10. Retrieved 2017-06-16.
- Rossman, P. Irwin III; Ted A. Maxwell; Alan D. Howard; Robert A. Craddock; David W. Leverington (21 June 2002). "A Large Paleolake Basin at the Head of Ma'adim Vallis, Mars". Science. 296 (5576): 2209–2212.
- "APOD: 2002 June 27 – Carving Ma'adim Vallis". antwrp.gsfc.nasa.gov. Retrieved 16 June 2017.
- Spirit rover follows up on scientific surprises". 4 January 2005. Retrieved 16 June 2017.
- U.S. Department of the Interior U.S. Geological Survey, Topographic Map of the Eastern Region of Mars M 15M 0/270 2AT, 1991