NASA's Mars Odyssey Points to Melting Snow as Cause of Gullies
A few relevant links:
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Nature Advance Online Publication (AOP)
Letters to Nature
19 February 2003
Formation of recent martian gullies through melting of extensive water-rich snow deposits
PHILIP R. CHRISTENSEN
doi:10.1038/nature01436
First paragraph
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NASA's Mars Odyssey Points to Melting Snow as Cause of Gullies
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(THEMIS Press Release, 2/19/03) Snow on Mars
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Alex R. Blackwell
University of Hawaii