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Valley Network
LIQUID WATER ON MARS
26. Valley Network (42°S,92°W)


Unlike the features shown in slides #23#25, many valley systems on Mars do not show evidence for catastrophic flooding. Instead, they show a greater resemblance to drainage systems on Earth, where water acts at slow rates over long periods of time. The valleys in this image are much smaller than the channels shown in slides #23#25. As on Earth, the channels shown here merge together to form larger channels. However, these valley networks are less developed than typical terrestrial drainage systems, with the martian examples lacking small-scale streams feeding into the larger valleys. Because of the absence of small-scale streams in the martian valley networks, it is thought that the valleys were carved primarily by groundwater flow rather than by runoff of rain. Although liquid water is currently unstable on the surface on Mars, theoretical studies indicate that flowing groundwater might be able to form valley networks if the water flowed beneath a protective cover of ice. Alternatively, because the valley networks are confined to relatively old regions on Mars, their presence may indicate that Mars once possessed a warmer and wetter climate in its early history. The area shown is about 200 kilometers across.

From Mars Digital Image Map, image processing by Brian Fessler, Lunar and Planetary Institute

Right click here to download a high-resolution version of the image (8.94 MB)




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