The nature and origin of gleyed polygenetic paleosols in the loess covered glacial drift plain of Northern Missouri, USA

摘要: Abstract At four study sites in northern Missouri the Farmdale and Sangamon paleosols, which are developed loess, welded to underlying Yarmouth paleosol, till. Upon initial examination, however, they appear be a single, thick, continuous gleyed horizon (Gleysol). Along flat tabular drainage divides this solum is identical all respects with historical definition of gumbotil. The may exceed 4 m thickness, but has little discernable horizonization. profiles nearly homogeneous, containing approximately 50% clay throughout most solum, 70–80% expandable minerals. Variations texture, mineralogy weathering indices typical forms complex, polygenetic profile. base retains abundant slickensided joints, upon exposure it rapidly develops shrink-swell features Vertisols. This behavior, coupled remarkable homogeneity within indicates that these soils underwent significant mixing, primarily by pedoturbation, characteristic modern