Wind velocity profiles were obtained over alluvial plains, lava flows, and a cinder cone in the Mojave Desert to determine the wind shear and the potential for particle transport. It was found that aerodynamic roughness, z0, for winds increases nearly a factor of 5 as flow crosses from the alluvium to the lave surface, resulting in wind shear that is 21% greater. Thus, wind erosion and sand flux may be substantially enhanced over the lava field. Moreover, wind flow turbulence is enhanced in the weak of the cinder cone, which also increases erosion and sediment transportation by the wind. ¿ 1987 American Geophysical Union