A yardang is a long ridge of rock or loess formed by wind erosion; yardangs run parallel to the direction of the prevailing winds.
The word is from a Turkish word meaning "steep bank".
Yardangs were first described by Sven Hedin in the deserts of Lop Nor in western China. Some geologists believe that the Sphinx in Egypt was carved from a sandstone yardang. And astronomers have discovered many yardangs on Mars!