Paleosols in loess deposits

Paleosols, in loess or other deposits, are soils of the past. Three types can be recognized, buried, exhumed (once buried, but now at the surface), and relict (not buried, but formed under a different environment in the past). In loess deposits, paleosols have stratigraphic significance as they represent times of minimal or no loess accumulation. In many parts of the world, loess-derived paleosols mark interglacial periods, but in other regions, loess accumulation and soil formation are competing processes that occur together during both glacial and interglacial periods. Identification of paleosols within loess sequences can be accomplished by recognition of soil morphological properties (A and B horizons), zones of pedogenic clay accumulation, zones of carbonate loss (humid regions) or carbonate gain (arid regions), distinct phosphorus depth functions, and magnetic properties. Once recognized, paleosols can serve not only as valuable stratigraphic markers, but can help in reconstructing past environmental conditions, particularly climate and vegetation. Such goals can be accomplished by determination of degree of chemical weathering in paleosols from chemistry and mineralogy, carbon isotopic composition of paleosol organic matter, phytoliths, and magnetic properties.