Some Mercurian Surface Features explained (False Colors; credits:

Caption NASA:"During MESSENGER's second Fly-By of Mercury, MDIS acquired a strip of HR images obtained with each of the WAC's 11 different color filters. The graphic shown here displays the resulting enhanced-color mosaic and gives considerable detail about the images, how the mosaic was created and the Geologic Features that can be seen.
Currently, these images are the Highest-Resolution color images ever obtained of the Solar System's innermost Planet, but not for long! On March 18, 2011, MESSENGER will enter into orbit about Mercury and the mission's extensive, year-long science observation campaign will begin.
That campaign includes capturing color images of Mercury's Surface at higher resolution than ever before".