Pathfinder Landing Site: Alternatives to Catastrophic Floods and An Antarctic Ice-Flow Analog for Outflow Channels on Mars

The Pathfinder spacecraft landed successfully at the mouth of the outflow channels Ares and Tiu Valles, returning a wealth of information about the surrounding landscape. One goal of the mission was to ascertain that catastrophic floods formed the outflow channels, the prevailing hypothesis for their origin. The follow-up reports on the mission proclaim that observations are "consistent" with an origin by catastrophic flood; no alternative mechanisms for channel origin are considered. Thus, the impression is given that the problem of channel origin has been solved. Yet none of the observations are diagnostic of origin by catastrophic floods. Other origins are possible but have been ignored, for instance origin as liquefaction mudflows, debris flows, mass flows, or ice flows. Here I will examine landing site observations that have been used to infer origin by catastrophic flooding and suggest alternative origins. Finally, I will highlight some new observation from Antarctica that make an ice-flow mechanism plausible for the origin of some of the outflow channels.