Curiosity Mast Camera Left photo taken on Sol 2611, December 11, 2019.
Credit: NASA/JPL-Caltech/MSSS

NASA’s Curiosity rover on Mars is now performing Sol 2613 duties.

Curiosity Mast Camera Left photo taken on Sol 2611, December 11, 2019.
Credit: NASA/JPL-Caltech/MSSS

“Curiosity is approaching another unconformity—or maybe it is a distant part of the same one. A large sloping surface called Greenheugh pediment looms ahead, past Western Butte,” reports Roger Wiens, a geochemist at Los Alamos National Laboratory in New Mexico. “Part of the exploration of Central and Western buttes is to determine their relationship to the unconformity.”

Wiens explains that, in a sedimentary environment, the principle of “superposition” specifies that lower rock layers were deposited earlier than the layers above them.

Rock record

“In other words, time effectively moves forward when traversing “up-section” (traversing to higher rock layers). That’s the direction that Curiosity has been moving,” Wiens adds, “so the rover is exploring rocks laid down more and more recently, though still a long time ago.”

Curiosity Mast Camera Left photo taken on Sol 2611, December 11, 2019.
Credit: NASA/JPL-Caltech/MSSS

Curiosity Front Hazard Avoidance Camera Right B image acquired on Sol 2612, December 11, 2019.
Credit: NASA/JPL-Caltech

Sometimes the rock record has an abrupt change due to missing rock layers that weathered or washed away before the next rock layer was deposited, Wiens explains. “The abrupt change in rock layers is called an unconformity.”

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