Introduction: Current temperature and pressure conditions on Mars suggest that liquid water is unstable at the surface with respect to boiling and freezing. However, gully features, generally consisting of alcoves , channels, and debris aprons and existing in a band at mid latitudes mainly in the southern hemisphere with a possible preference for pole-facing orien-tations [1, 2], suggest liquid...

A gully is an excavation cut in the immediate footwall or hangingwall of the reef for the purpose of enabling the removal of rock from the face or providing access to the face for mining personnel or material1. The gully sidewalls and hangingwall often pose a serious stability problem in the gold and platinum mines in South Africa, since records of fatal rock-related injuries show that they are...

Martian gullies are geologically recent small-scale features characterised by an alcove-channel-apron morphology associated on Earth with liquid water. Since their discovery by Malin and Edgett (1), several theories have been advanced to explain their formation. These typically emphasise either groundwater processes (1, 2) or melting of ground ice or snowpack (3). The former approach has been c...

Introduction: A stereo pair of HiRISE images of a pole-facing crater slope at 38S, 218E shows many fresh looking gullies. After measuring slopes using the stereo viewing geometry, we estimate the expected fluvial discharge rates using theory from Kleinhans [1] and Ikeda [2]. We also develop a numerical model of sediment transport based on theory presented in Kleinhans [1] to determine the time ...

Liquid water is not stable under current martian surface conditions, but the presence of small gullies on the polewardfacing slopes of midto highlatitude martian surfaces suggests that erosion by liquid water might have occurred. Costard et al. (p. 110) developed a global climate model for Mars when it had a higher obliquity (about 300,000 years ago). Their model shows that more melting of the ...

Introduction: The discovery of gullies on Mars [1,2] resulted in a wide variety of proposed candidate mechanisms for formation but ensuing analyses have shown very strong latitude and orientation dependencies on their distributions [3-6]. These constraints have been interpreted to require: 1) a volatile on or near the surface as a source of liquid water, and 2) insolation and slope orientation ...

Introduction: First identified by Malin and Edgett [1], gullies are among the youngest and most enigmatic geomorphic features on Mars. Originally hypothesized to be the result of confined aquifer breakouts, they have subsequently been interpreted to be the result of dry mass flows (e. shown persuasively that the global distribution of gullies is preferential. The greatest concentrations of gull...

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Introduction: The latitude dependent distribution [1-3] and non-uniform orientations [4-8] of young gullies on Mars suggest that their formation and modification are controlled by the activity of volatiles at or near the surface. Given the relative abundance of gullies and Mars' current thermal environment, CO 2 and H 2 O are the most likely candidates for contributing to gully evolution. Conte...