There are unusual occurrences of reddish coloured soils on the upland along the coastal region of the Okhotsk Sea. The topography of the region is consist of three terraces named T_1, T_2 and T_3 from higher towards lower and of gentle slopes or erosion surfaces extending to mountainous region behind the highest terrace (T_1). These terraces may be distinguished from each other by means of relative height, stratigraphy and degree of dissection. It seems to be very important that the most of reddish coloured soils distribute on the gentle slope, and some of them on the highest terrace (T_1), but never on lower terraces (T_2 and T_1). Furthermore, it is also notable that there is no definite causal connection between reddish colour of soils and their parent materials. In these reddish soil profiles, following common morphological characteristics are observed. General horizon sequence may be shown as A_0/A_1/ A_3/B_1/B_2/C_1/C_2. The morphology of the upper part of the profile (above B_1 horizon) seems to closely resemble that of Acid brown earth commonly developed in this region. On the other hand, the lower part (below B_2 horizon) is characterized by distinct reddish colour (10R-5YR in MUNSELL'S notation), heavy texture, well developed blocky structure, as well as compact, plastic and sticky constitution. In the C horizon occasionally a sort of reticulated pattern is observed. These features seem to give marked coinsidence with those of subsoil in, zonal Red soils in humid subtropical zone. It was be quite reasonable to assume that the lower part of the reddish soil profile should be a "relic" of Red soils or weathering crust of them which could be formed under much warmer climatic conditions during a given geological age, perhaps in Riss/Wurm Interglacial, judging from stratigraphical, geomorphological and soil morphological evidences, as well as the geographical or latitudinal situation of this region. To the contrary, the upper part of the profile may be inclined to develop Acid brown earth under recent humid cool-temperate bio-climatic circumstances.
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