A rock outcrop dubbed "Missoula," near Marias Pass on Mars, is seen in this image mosaic taken by the Mars Hand Lens Imager on NASA's Curiosity rover.

July 23, 2015

A rock outcrop dubbed "Missoula," near Marias Pass on Mars, is seen in this image mosaic taken by the Mars Hand Lens Imager on NASA's Curiosity rover. Pale mudstone (bottom of outcrop) meets coarser sandstone (top) in this geological contact zone, which has piqued the interest of Mars scientists.

White mineral veins that fill fractures in the lower rock unit abruptly end when they meet the upper rock unit. Such clues help scientists understand the possible timing of geological events. First, the fine sediment that now forms the lower unit would have hardened into rock. It then would have fractured, and groundwater would have deposited calcium sulfate minerals into the fractures. Next, the coarser sediment that forms the upper unit would have been deposited.

The area pictured is about 16 inches (40 centimeters) across. The image was taken on the 1,031st Martian day, or sol, of the mission (July 1, 2015).

Credits

NASA/JPL-Caltech/MSSS

ENLARGE

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