South of Prebaikalia is the region with compound, complex soil cover. Cause of formation for complex soil cover is relict microrelief, which is introduced pit and mound microrelief. It is pits and mounds, which have 10-20 m in diameter and 1-3 m in height. It promotes for difference of soil formation, determining chemical, physical and biological properties of soils. The principal cause of this phenomenon is polygonal cracking because of very rapid cooling of the climate, which took place to the end Pleistocene – 10,5 –11 thousand of years ago, approximately. As a result of warming and weathering, had been happened to the Holocene, mounds were formed from the polygons and pits were formed from the cracks. Soils, developed in this relief, have different horizons, properties, regimes and ecological functions.