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These layered hills, seen on this false-colour picture of a portion of Arabia Terra on Mars, could probably have a watery origin. Arabia Terra is a highland area in Mars’ northern hemisphere, relationship again to the crimson planet’s Noachian geological period, round 4 billion years in the past. Given the area’s nice age, it sports activities many craters, inside which are sometimes discovered layered mounds corresponding to these on this picture from NASA’s Mars Reconnaissance Orbiter.
The layered rocks in Arabia Terra are available in three varieties. The primary sort, seen on this picture, is described by alternating layers of sunshine and darkish materials, which can symbolize episodic intervals of sedimentary deposition. One can think about an historic lake filling the crater through which these mounds are positioned, the shoreline altering as the ocean stage assorted with the Martian local weather, the tides abandoning alternating layers of mudstone and limestone. Or, maybe the layers signify totally different volcanic occasions that interrupted the same old depositional processes by dumping layers of ash onto the mounds.
The second sort consists of layers that appear to be they’re composed from the identical materials and type ‘stair-step’ mesas, whereas the third sort options darkish, skinny layers of rubbly, uneven materials, and infrequently produce boulders that roll down slopes. This third sort might be the results of lava having as soon as flowed by means of a sandy area; afterwards, the basaltic rock hardened, and on cliff edges the place sandy materials crumbles away, the bigger chunks of basaltic rock find yourself giving means and rolling right down to the underside of the crater flooring. Picture: NASA/JPL–Caltech/College of Arizona.
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