Besides clouds and moisture, there is also wind in the Martian atmosphere. The sand drifts around this rock show proof of the power of the winds of Mars.
On Mars, the winds accelerate to higher speeds than on Earth so that the sand grains are accelerated to higher speeds as well, and for a greater length of time. (This leads to a different angle of impact of sand grains on rocks and affects the gouging and chipping power of sandblasting winds). Because of Mars' lower gravity, the winds can more easily lift and carry sand particles. But the lower atmospheric pressure of Mars makes it harder for the winds to move sand particles. This makes the erosion of Martian rock a little different than on Earth.