We investigates the morphological characteristics, composition and properties of soils in pine forests of the Selenga middle mountains in Western Transbaikalia which contain buried humus horizons with inclusions of charcoal particles and are the product of soil transformation and development in regions of intense pyrogenesis. Analysis of the soil morphology revealed that the buried humus horizons are dark colored and aggregated typical for the humus-accumulative soil horizons; they differ from the modern horizons by their smaller thickness and higher compactness. Submicroscopic analysis of charcoals collected from paleohorizons showed their good stability caused by climatic conditions. The study revealed pyrogenic transformations of the structure of th ere buried horizons and the presence of humus accumulations, exchange bases and silt particles. Data on fraction-group composition of humus in buried horizons indicate a transformation of a part of humic acids to the insoluble residue and an increase in the contribution from calcium humates due to pyrogenic impacts. It is established that the morphological diagnostics, physicochemical analysis and data on submicrostructure of soil aggregates and charcoal particles in the paleohorizons presented reflect important formation stages of soils and their transformation and confirm a strong cyclicity of soil formation in conditions of intense influences of forest fires in the region.Keywords: pyrogenesis, accumulation of charcoal particles, humus transformation.