The soil formation within the Wet Atlantic Chernozem facies of the West-Ukrainian region leads to the vertical redistribution of Chernozem soil substance and formation of the differentiated mineral soil profile to varying degrees by carbonates, clay, and chemic-mineralogical composition. Luvic Greyzemic Chernozems (Siltic, Aric, Pachic) is characterized by the sharp differentiated profile by clay. The degree of vertical differentiation of clay profile is directly proportional to the intensity of the processes of leaching and gleyzation. In mineral profiles of Luvic Greyzemic Chernozems the vertical redistribution of clay material is mainly due to fraction smaller than 0.02 μm. The opposite character of profile distribution of mica-smectite and illite phases of clay minerals was discovered. Against the unbalanced losses of a part of clay plasma in the humus horizon, the process of relative illitization was detected due to smectite eluviation and accumulation of illite, kaolinite and finely dispersed quartz.