The top of the image shows a dark surface that is extremely rough and rocky. The rest of the image shows a brighter, smoother material. It appears that the bright material has been been eroded back, exposing the lower, darker surface.
Illumination is from the upper left.
Tolstoy Crater, in which the small unnamed crater seen in this picture occurs, was named by the International Astronomical Union in 1982 to honor the Soviet writer who died in 1945. It is one of only a few craters on Mars designated by both the first and last names of the honored person. Malin Space Science Systems and the California Institute of Technology built the MOC using spare hardware from the Mars Observer mission.