In the bases of multi-level dumps three complexes of rocks characterized by different physical and mechanical properties are clearly distinguished. The first complex is represented by modern soils of floodplain terraces of river valleys and gullies. Its thickness is 0.5-15 m. The soils of this complex are fully water-saturated, highly compressible and have extremely low shear resistance. They form weakening zones in the bases of dumps, where creep phenomena and extrusion landslides develop. The soils of this complex require special engineering measures aimed at drainage and strengthening. ...