This view from the Mast Camera (Mastcam) on NASA's Curiosity Mars rover shows a site where two different types of bedrock meet on lower Mount Sharp.
The scene combines multiple images taken by the left-eye camera of Mastcam on May 25, 2015, during the 995th Martian day, or sol, of Curiosity's work on Mars, in a valley just below "Marias Pass." The color has been approximately white-balanced to resemble how the scene would appear under daytime lighting conditions on Earth.
The paler part of the outcrop, in the foreground, is mudstone similar to what Curiosity examined in 2014, and in early 2015, at "Pahrump Hills." The darker, finely bedded bedrock higher in the image and overlying the mudstone stratigraphically is sandstone that the rover team calls the "Stimson" unit.
The scene covers an area about 10 feet (3 meters) wide in the foreground.
Malin Space Science Systems, San Diego, built and operates the rover's Mastcam. 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.
http://photojournal.jpl.nasa.gov/catalog/PIA19676