English: This picture was taken by the Viking Lander 1 on February 11, 1978 on Sol 556. The large rock just left of the center is about two meters wide. This rock was named "Big Joe" by the Viking scientists. The top of the rock is covered with red soil. Those portions of the rock not covered are similar in color to basaltic rocks on Earth. Therefore, this may be a fragment of a lava flow that was ejected by an impact crater.

Based on images from the NASA Viking image archive

Crop/Up-Resize/JPG-Convert (using JASC Paint Shop Pro v 6.02) of file at https://en.wikipedia.org/wiki/File:Mars_Viking_11h016.png