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Cross-bedding seen in the layers of this Martian rock is evidence of movement of water recorded by waves or ripples of loose sediment the water passed over.
This image was acquired by the Mast Camera (Mastcam) on NASA's Curiosity Mars rover, at a target called "Whale Rock" in the basal geological unit of Mount Sharp. The Mastcam's left-eye camera took it during the 796th Martian day, or sol, of Curiosity's work on Mars (Nov. 2, 2014).
The color has been approximately white-balanced to resemble how the scene would appear under daytime lighting conditions on Earth. Figure 1 is a cropped version with a superimposed scale bar of 30 centimeters (about 12 inches) just beneath cross-bedding, which is evident in the layers at angles to each other.
This example of cross-bedding shows evidence of small "climbing" ripples that migrate on top of each other (just above "10" in scale bar of Figure1). This suggests currents of water entered into a lake basin, possibly flowing down the front of a delta, and then spread out across the lake floor, slowing down, and depositing sediment.
The location of Whale Rock within the "Pahrump Hills" outcrop in the Murray formation at the base of Mount Sharp is indicated on an earlier Mastcam view at PIA19039.
NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology, Pasadena, manages the Mars Science Laboratory Project for NASA's Science Mission Directorate, Washington. JPL designed and built the project's Curiosity rover. Malin Space Science Systems, San Diego, built and operates the rover's Mastcam.
More information about Curiosity is online at http://www.nasa.gov/msl and http://mars.jpl.nasa.gov/msl/.