Ridges Show Evidence of Water on Mars: NASA Images
It turns out that there is further evidence of water flowing beneath the surface of Mars. A study published in the journal Geophysical Research Letters shows that ridges in impact craters on Mars appear to be fossils of cracks in the Martian surface. These cracks would have been formed by minerals deposited by flowing water beneath the surface.
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The researchers, Lee Saper and Jack Mustard, examined images of ridges on the Martian surface. Many of the ridges were hundreds of feet in length and only a few feet wide. While they had been noted in previous research, how they had formed was a mystery. Saper and Mustard came up with a theory that they believe could explain these ridges.
These formations may once have been faults and fractures that formed underground when impact events--such as a meteor strike--occurred. If water was present at the subsurface, it would have circulated through these cracks and would have slowly filled them with mineral deposits. These minerals would have been harder than the surrounding rocks and while the softer material would have eroded over millions of years, the harder deposits would have remained. These would have formed the ridges that are seen today.
Before the two researchers could draw any conclusions, though, they had to test their hypothesis. They mapped over 4,000 ridges in two crater-pocked regions on Mars. Using high-resolution images from Mar's Reconnaissance Orbiter, they then examined the orientations of the ridges and the composition of the surrounding rocks.
Their findings were consistent with their theory and debunked a competing hypothesis that suggested the structures may have been sheets of volcanic magma pushing through the surrounding rock. In addition, the scientists found the ridges existed exclusively in areas where the surrounding rock is rich in iron-magnesium clay, a mineral that's usually considered to be a telltale sign that water has been present.
These findings suggest that Mars once had plentiful supplies of water, and may point to further evidence that there was once life on the red planet.