title: A large paleolake basin at the head of Ma'adim Vallis, Mars.
abstract: At 8 to 15 kilometers wide, Ma'adim Vallis is one of the largest valleys in the martian highlands. Although a groundwater source was previously suggested, the channel originates at a spillway in the divide of a approximately 3,000,000-square-kilometer closed drainage basin. The interior morphology of this source basin, including likely shoreline features following topographic contours, suggests that Ma'adim Vallis was created through catastrophic overflow of a approximately 1,100,000-square-kilometer highland lake. The size, constant levels, and interior morphology of three regional paleolake basins require a warmer paleoclimate and a long-term, recharged, stable highland water table more than approximately 3.5 billion years ago.
authors.affiliation: Center for Earth and Planetary Studies, National Air and Space Museum, Smithsonian Institution, Washington, DC 20560, USA. Irwinr@nasm.si.edu
authors.forename: Rossman P
authors.initials: RP
authors.lastname: Irwin
authors.forename: Ted A
authors.initials: TA
authors.lastname: Maxwell
authors.forename: Alan D
authors.initials: AD
authors.lastname: Howard
authors.forename: Robert A
authors.initials: RA
authors.lastname: Craddock
authors.forename: David W
authors.initials: DW
authors.lastname: Leverington
mesh_terms: D005118:Extraterrestrial Environment; D018535:Mars; D013995:Time; D014867:Water
chemical_list: D014867:Water