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Stair-Stepped Mounds in Meridiani Planum
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Stair-Stepped Mounds in Meridiani Planum

September 8, 2008

This image shows layered sedimentary rocks that fill an impact crater in the Meridiani Planum region of Mars.

These layered rocks may have formed through the accumulation of sediment (sand and dust) that were transported into this crater by blowing wind or flowing water. These sediments formed an extensive deposit that once covered the floor of the surrounding impact crater.

This crater is so large that the HiRISE image is entirely within it, and the crater rim is not visible. These sedimentary rocks were then eroded, likely by the wind. The original sand and dust were deposited in distinct layers within the crater; these layers now give the mounds their distinctive stair-stepped appearance, and are all that remain from this once extensive deposit.