To determine the values of the lower escarpment angles in (19) for the first time conducted ridges experimental studies composed of sediments with the average particle diameter of d=0.23 mm. Analyzing of experiments results involving materials of field studies and experimental **data** of other authors, he concluded that the angle of the ridges lower escarpment in changing their forms until antidune does not depend on the flow hydraulic characteristics and it is determined by the value of the relative density of noncohesive grounds: = 7.08 0.19 1 (1)