For 10 points, name these hill-like accumulations of material often found in deserts.
These features can be morphologically classified by their RDP to DP ratio, which is defined only above the threshold shear velocity. The nabkha, or coppice, type of these features are anchored by shrubs or other plants. Ecologist Henry C. Cowles wrote his dissertation on the rapid plant succession that he observed in these features in Indiana. The presence of vegetation facilitates the parabolic type of these features, which point in the opposite direction from the crescent-shaped barchan ("bar-can") type. These features migrate as material from their stoss side moves to the steeper slip face on the lee side, which sits at the angle of repose. These features, which are found in large numbers in ergs, form when saltating particles are deposited in the wind shadow behind an obstacle. For 10 points, name these hill-like accumulations of material often found in deserts.
These features can be morphologically classified by their RDP to DP ratio, which is defined only above the threshold shear velocity.
sand dunes [anti-prompt (ask “can you be less specific?”) on specific types of dunes such as nabkha, draa, or ergs] &lt;Other Science (Earth Science)&gt;