This image shows the rock Yogi and tracks from the Rover. Click on image for full size version (40K GIF) Image from: JPL/NASA

There are two main weathering agents on Mars: wind and acid fog. Although acid fog can be very important, because large amounts of water are not readily accessible from the Martian surface, the action of sand and wind is the main agent of weathering on Mars.

Wind erosion of Mars was examined in the Mars Pathfinder mission. Rocks examined by the Pathfinder's Rover found evidence of the following erosion features:

• wind tails, or drift deposits
• ripples
• albedo differences
• moats
• duneforms
• ventifacts

Sand and dust from the surface is whipped up by the winds of Mars and distributed around the globe in global dust storms. The force of winds during these storms pounds sand into the rock formations, contributing toward the breakdown and recycling of the Martian surface.