The structure of sediments at low (1–3 m), middle (3–5 m) and high (5-8 m) floodplains of the Belaya River valley is studied. The features of alluvial sedimentation in different periods of the Holocene (MIS-1) and Last Pleistocene (MIS-2) are revealed. The upper horizons on all the floodplains of the Belaya River has the sub-Atlantic age (SA) of the Holocene. In Holocene (MIS-1) time the wide distribution of dark humus (AU) and gray humus (AY) horizons is observed. In Last Pleistocene (MIS-2) time primitive soils containing a low of humus are formed. The properties of existing and buried soils were studied at the flood-lands of the Belaya River. There is a dependence on the height of the floodplain and the distance from the river of soil with different sediment`s sizes in the soil. The problems of recording of the soil formulas of alluvial soils show their complex structure. You can use the results of research for other rivers in the region, since the Belaya River is typical for many tributaries of the Angara River.