A 3-D image of an impact crater in the Nilosyrtis area on the Martian surface shows
long pipe-like ridges, fossilized evidence of ancient subsurface water flow.
Credit: NASA Mars Reconnaissance Orbiter

EARTHSKY // SCIENCE WIRE RELEASE DATE: JAN 29, 2013

Ridges on Mars suggest ancient flowing water

Ridges in impact craters on Mars appear to be fossils of cracks in the Martian surface, formed by minerals deposited by flowing water.

Networks of narrow ridges found in impact craters on Mars appear to be the fossilized remnants of underground cracks through which water once flowed, according to a new analysis by researchers from Brown University.

The study, in press in the journal Geophysical Research Letters, bolsters the idea that the subsurface environment on Mars once had an active hydrology and could be a good place to search for evidence of past life. The research was conducted by Lee Saper, a recent Brown graduate, with Jack Mustard, professor of geological sciences.

The ridges, many of them hundreds of meters in length and a few meters wide, had been noted in previous research, but how they had formed was not known. Saper and Mustard thought they might once have been faults and fractures that formed underground when impact events rattled the planet’s crust. Water, if present in the subsurface, would have circulated through the cracks, slowly filling them in with mineral deposits, which would have been harder than the surrounding rocks. As those surrounding rocks eroded away over millions of years, the seams of mineral-hardened material would remain in place, forming the ridges seen today.

Read more: Ridges on Mars suggest ancient flowing water | Science Wire | EarthSky.

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