These features are frequently found in ergs.
For one type of these features, small ones appear to pass through the slower-moving large ones, leading to comparisons of that type with solitons. Similar larger-scale features are called draas. The main processes leading to the creation of these features are surface creep and (*) saltation, which are both aeolian. These features are frequently found in ergs. The slip face of these features forms an angle of about 34 degrees with the surface, the angle of repose for its constituent material. Vegetation fixes the arms of parabolic ones, which point upwind. Other types of these features include longitudinal ones and barchans, or the crescent type. For 10 points, name these large accumulations of sand.
For one type of these features, small ones appear to pass through the slower-moving large ones, leading to comparisons of that type with solitons.
sand dunes