Solid Evidence that Water Flowed on Mars
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Solid Evidence that Water Flowed on Mars

November 14, 2003
The most recent MOC discovery: an ancient, eroded, and exhumed sedimentary distributary fan located in a crater at 24.3°S, 33.5°W. A distributary fan is a generic term used by geologists to describe a family of deposits that includes river deltas and alluvial fans. Sometime in the distant past, when it was still possible for liquid water to flow across the martian surface, sediments transported through valleys by water formed a fan-shaped deposit in a 64-kilometer (40 miles) -diameter crater northeast of Holden Crater. What is important about this discovery? First, it provides clear, unequivocal evidence that some valleys on Mars experienced the same type of on-going, or, persistent, flow over long periods of time as rivers do on Earth. Second, because the fan is today a deposit of sedimentary rock, it demonstrates that some sedimentary rocks on Mars were, as has been suspected but never clearly demonstrated, deposited in a liquid (probably water) environment. Third, the general shape,

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