Geomorphological Surfaces and Red Weathering Crusts in Northeast Japan

Abstract

Based on the study on the geomorphological surfaces in Northeast Japan, the author concluded that the red weathering crusts were formed in the following two stages.
The older stage is represented by the hillocks with red weathering crusts. The sea level in this stage was 100m higher than the present level. This stage was followed by the stage which characterized by the deposition of debris or clayey materials (Figs. 4-7).
The younger one was followed by the stage of the “cryopediment” (Wako, 1963a) formation which prevailed in the valleys of Northeast Japan about 25, 000 yr. B. P. The lowest coastal terrace with red weathering crust stands 25m. above the sea level. The genesis of such weathering crusts in Japan was attributed to the former humid subtropical climate by some pedologists (e. g., T. Matsui and Y. Kato, 1962). Granted that the assumption is true, it seems probable that there was a certain relationship between the subaerial process of the hill surface formation and the conditions for red weathering occurrence.