ABSTRACT
The formation of the Loess Plateau started about 2.5 million years ago. Since then, a series of loess layers (brown-yellow, silty, eolian deposits) and paleosols (reddish, clayey loam) have formed and accumulated to a depth of 100 to 200 meters, called loess-paleosol series in this paper, which is the thickest and most complete loess deposition in the world. The formation processes of the Loess Plateau are in essence the processes of loess accumulation. Loess deposits and paleosols have a loose and porous structure, which has frameworks composed of sands and other coarse particles, filled with fine particles and micro-aggregates, and strengthened by clayey materials. Such a porous medium is very susceptible to water erosion if not protected by plants. This is indeed the reason why soil and water losses are so severe in the Loess Plateau.
