This mosaic of images from Curiosity's Mast Camera (Mastcam) shows geological members of the Yellowknife Bay formation. The scene has the Sheepbed mudstone in the foreground and rises up through Gillespie Lake member to the Point Lake outcrop.
These rocks record superimposed ancient lake and stream deposits that offered past environmental conditions favorable for microbial life. Rocks here were exposed about 70 million years ago by removal of overlying layers due to erosion by the wind.
The scene is a portion of a 111-image mosaic acquired during the 137th Martian day, or sol, of Curiosity's work on Mars (December 24, 2012). The foothills of Mount Sharp are visible in the distance, upper left, southwest of camera position.