Clay minerals included in the three major sand dune soils in Tottori Prefecture, located at the Japan Sea Coast, a humid temperate area, were investigated with X-ray and thermal analyses. In the surface soils under black pine (Pinus thunbergii Parl.) vegetations, where the accumulation of humus subustances and the progress of silt and clay formation were observed, mica clay mineral, chlorite, vermiculite and kaolinite, accompanied with gibbsite and in some cases with a little smectite were detected in the all three dunes. Chlorite is considered to be formed through the accumulation of the hydroxides within the interlayer of vermiculite and/or smectite under the conditions of weakly acid, low contents of humic substances, and alternative wet and dry soil moisture conditions in the sand dune surfaces under the pine vegetation. In Tottori Dune, distributed in the eastern area of Tottori Prefecture, the similar composition of the clay minerals in the surface soils under the pine vegetation were recognized also in the clay fraction of subsoils under the pine vegetation and in both cultivated surface soils and subsoils with little or almost no organic matter (where the clay contents were around 1%). The clay minerals observed in such cases were presumed to be derived from the Sangun metamorphic rocks including chlorite distributed in the upperstreams of Sendai River supplying the dune materials of this area. In Hojo Dune, in the central area of the prefecture, little crystalline clay minerals other than the small amounts of amorphous oxides of Si, Al and Fe were detected in the clay fractions in the subsoils under pine vegetation and both in surface- and subsoils of cultivated lands in which the clay contents were around 0.3%. In this area no metamorphic rocks are detected in the upperstreams of the main water system of Tenjin River. In Yumihama Dune, in the western area of the prefecture, though the amounts were less, the above mentioned crystal clay minerals were detected also in a subsoil under pine vegetation as well as in the Tottori Dune. In the surface soil of a cultivated land composed of "kurosuna" ("black sand", contains about 2% clay), which probably contains components of the metamorphic rocks contained crystalline clay components nearly same as in Totori Dune, though in the subsoil little crystalline clays were detectted. In the region of the upperstreams of Hino River which supplies the dune materials of this area, the Sangun metamorphic rocks are distributed in smaller areas than those of Sendai River.

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Genesis and classification of the soils derived from marl under natural vegetation and cultivated crop land in Kikai and Okinawa Islands were studied based on their physico-chemical and mineralogical properties. The results are as follows: 1) Under natural vegetation in Kikai Island, the soil derived from marl has A-Bw1-Bw2-BC-C horizon. The cambic B horizon is dull yellowish brown to yellowish brown (10YR5/3 or 2.5Y5/3) in color, medium subangular blocky structure. Soil reaction is slightly acid (pH5.1-6.2) and the degree of base saturation is 74-111%. The organic carbon content of A horizon is 40.4 g ・kg^<-1> and decreases with depth. 2) Under natural vegetation in Okinawa Island (Yonabaru), the soil derived from marl has A-BA-Bw-BC-C horizon. The cambic B horizon is dark grayish yellow (2.5Y4/2) in color, medium subangular blocky structure. Soil reaction is slightly alkaline (pH8.0-8.5), the free carbonate is 58.3-85.8 g kg^<-1>. The organic carbon content decreases with depth (23.1-8.3 g kg^<-1>). 3) Under cultivated crop land in Okinawa Island (Kochinda), the soil derived from marl has A-ACg-C1g-C2-C3g horizon. The differentiation of horizon is not developed and its structure is massive except A horizon. 4) In Kikai and Yonabaru soil, the activity ratio of free iron oxides (Fe_o/Fe_d) ranges from 0.37 to 0.59, and the crystallinity ratio of free iron oxides [(Fe_d-Fe_c)/Fe_t] ranges from 0.12 to 0.24, while in Kochinda soil, they range from 0.16 to 0.25 and from 0.25 to 0.37, respectively. Under cultivated land, crystallization of amorphous free iron oxides proceeds more than under natural vegetation. 5) Soils under natural vegetation, Kikai and Yonabaru, ate approximately correlated with Orthieutric Cambisol and Calcaric Cambisol in WRB, respectively. While in USDA Soil Taxonomy, both Kikai and Yonabaru soils are correlated with Typic Eutrudept. On the other hand, the cultivated soil, Kochinda, is correlated with Calcaric Regosol in WRB or Typic Udorthent in USDA Soil Taxonomy.

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This paper reports the findings of an examination of the hilly land of Bi-ei, which is composed of pyroclastic flow sediments. The Soil genesis of the Bi-ei hilly lands were examined relative to its position in the hills, the form of the slopes, and the detail of the landform. A summary of the analysis and measurements follows: 1. The hilly land of Bi-ei is composed of pyroclastic flow sediments extruded from Mt. Tokachi-dake. The altitude of the hilly land of pyroclastic flow sediments decreases as the land gets farther from the center of extrusion. 2. The upper part of the hilly land is characterized by a narrow hilltop and a broadly sloping area. In the peripheral hilly land at lower altitudes, the hilltops are broader and narrower. Thus, the landform is comprised of undulate and flat surfaces. 3. The soil in the upper part of the hilly land is brown forest soil. Erosion was severe on the upper slopes, and the humic layer is thin. The texture is medium coarse to coarse, and the bedrock can be observed at shallow depth. On the lower slopes, the soil layer is thick and has a high humus content. The texture is fine to medium coarse due to the accumulation of eroded soil from the top and upper areas of the hill. The soil on the peripheral hilly land is finely textured brown forest soil on the undulate hilltop surfaces, while finely textured gray terrace soil is prevalent on the flat surfaces of the hill. 4. From the condition of the landform and the distribution of the soil surface, it was concluded that the landform condition greatly affected the formation of the hilly land of Bi-ei Soil erosion, secondary sedimentation, and sorting of grain-size due to lacustrine deposit formation also contributed to the formation of the landform.

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We studied chemical and mineralogical properties of four soil profiles at lower elevations of Mts. Shirakami. These soils are located in the area where Brown forest soils are assumed to be dominant according to literature. Morphological properties of the four soils were characteristic of Brown forest soils. But bulk densities of the soils were lower than those of ordinary Brown forest soils. Not only A horizons but B horizons contained large amounts of organic carbon. Most soil samples showed strong to moderate acidity (pH(H_2O) 4.6-5.3). The amounts of exchangeable basic cations in most mineral horizons were extremely small and KCl-extractable Al was the dominant exchangeable cation. The results of selective dissolution analyses using pyrophosphate and acid oxalate solutions showed that there is no severe eluviation of aluminum and iron in all the soil profiles, though slight migration of aluminum to lower horizons were observed. Although only one A horizon contained expandable 2:1 minerals that are common to most Spodosols, 2:1 minerals in the other soil horizons were remarkably chloritized. Most soil horizons of the four pedons possessed andic soil properties. A large amount of Al-humus complexes accumulated in the upper soil horizons and allophonic clays were formed in the lower horizons. Although the pedons in this study were classified as Brown forest soils according to Classification of Forest Soil in Japan, they were classified as Andisols and Andosols according to Soil Taxonomy and World Reference Base for Soil Resources, respectively

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