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SlideshowReport

Rivers on Mars and Earth

Description
(a) Winding canyons on Mars, such as the one in this Viking 1 orbiter
image, appear to be formed by sustained water flow. This theory
is supported by the terraces seen on the canyon walls in
high-resolution Mars Orbiter images. Long periods of water
flow require that the planet’s atmosphere was once thicker
and its climate more Earthlike
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