This image shows the rock called "Souffle".
Click on image for full size
Image from: NASA/JPL
Martian Surface Winds
The surface pressure of Mars is about 1/150th that of the surface pressure of the Earth. This means that there are much fewer molecules in the atmosphere. This means that the atmosphere near the surface of Mars has much less inertia than that near the surface of the the Earth. Putting the atmosphere of the Earth in motion must be like putting molasses in motion compared to putting the atmosphere of Mars in motion. This means that the Martian surface winds can be accelerated to higher speeds than those on Earth, see the classes of terrestrial wind speeds. The general circulation pattern of winds is also very different from the terrestrial circulation pattern. These winds can be whipped to an extreme during the frequent Martian global dust storms.
Because of Mars' lower gravity, the winds can more easily lift and carry sand particles. Sand particles from the surface driven by winds contribute to sand erosion of the surface. Features found by the Mars Pathfinder lander provided plenty of evidence for sand erosion by wind. But the lower atmospheric pressure of Mars makes it harder for the winds to impart momentum to sand particles lying on the ground. Thus the amount of sand grains lifted from the surface are accelerated to high speeds may be different from what would be expected on the Earth. This makes the erosion of Martian rock a little different than on Earth.
The first weather measurements made from the surface of Mars were performed by the Mars Pathfinder mission. These measurements provided some "ground truth" for the strength of Martian winds.
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