Editing Gully (section)

==On Mars==
{{Main|Gullies on Mars}}

Gullies are widespread at mid-to-high latitudes on the surface of [[Mars]] and are some of the youngest features observed on that planet, probably forming within the last few 100,000 years. There, they are one of the best lines of evidence for the presence of [[Water on Mars|liquid water on Mars]] in the recent geological past, probably resulting from the slight melting of snowpacks on the surface<ref>Christensen, PR (2003). "Formation of recent martian gullies through melting of extensive water-rich snow deposits.". Nature 422 (6927): 45–8. {{doi|10.1038/nature01436}}. {{PMID|12594459}}.</ref> or ice in the shallow subsurface<ref>Costard, F., Forget, F., Mangold, N. & Peulvast, J. P. Formation of recent martian debris flows by melting of near-surface ground ice at high obliquity. Science 295, 110–113</ref> on the warmest days of the Martian year. Flow as springs from deeper seated liquid water [[aquifers]] in the deeper subsurface is also a possible explanation for the formation of some Martian gullies.<ref>Malin M. C. and Edgett K. S. (2000) Science, 288, 2330–2335.</ref>