Microscopic observations of the recent soils: a step for understanding the paleosols

The microscopic observations of the recent soil horizons were conducted in Okayama, Japan (moderate climate). The several soil horizons, including two surface (epipedon) and three subsurface horizons, were recognized in the forest, poorly vegetated hill, and riverside around the Okayama University. The umbric epipedon can be segregated from the organic-rich subsurface horizons by the scattered organic materials in thin sections. The ochrich epipedon shows the sandy matrix without any cements and the illuviation of clay minerals. The subsurface horizons identified in the study area are as follows: albic, argillic, and cambic horizons. Each subsurface horizon shows the specific structures in thin sections. The albic horizon is characterized by the absence of the illuviation. The argillic horizon definitely shows the clayey matrix and the illuviation of clay minerals. The primary structures may be retained in the cambic horizon. The microscopic examination of the Miocene paleosols from the Ukan-cho, Okayama, was attempted. By comparing the recent soils, the cambic horizon and spodic horizon, which is characterized by the concentration of sesquioxides, are identified in the paleosols. This attempt suggests that the microscopic observations of the recent soils is a useful guide to understanding the paleosols