Martian mid-latitude gullies

Martian mid-latitude gullies
Martian mid-latitude gullies Are martian mid-latitude gullies the product of melting snow packs, or has the fluid which carved the gully channels come from within the ground? Ground water or melted ground ice would seem to be favored by observations such as shown here, where channels originate from beneath an overhang (arrow) on the wall of a depression (the direction of flow is toward the bottom of the image). In this particular case, the depression is Dao Vallis, an area considered by some to be the "type locality" for examples illustrating the snowmelt hypothesis. The point is, the origin and source of fluid involved in martian gully formation remains unclear and the gullies could be key indicators that Mars still has liquid water beneath its surface today. This is a sub-frame of MGS MOC image S14-01017. NASA / JPL-Caltech / MSSS

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