中央日本の山地における洪積世氷期の堆積段丘 (寒冷気候にまつわる諸問題(特集)) -- (寒冷気候下の現象)

概要

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The author has investigated three examples of accumulation terraces originated from Quaternary Ice Age at the upstream area in the high mountain in central Japan, namely at the River Yabusawa, Akaishi Mts., the River Gamata and the River Azusa, Hida Mts.These terraces are classified into two types. The first type is a dissected moraine or a dissected out wash which is situated in the proglacial site where the altitude continues to a cirque bottom. The second type which consists of a large quantity of sands and gravels is situated in the downstream to the site of the first type. The huge accumulation might have made by the overloaded stream having carried much detritus from the slopes above the timberline which had lowered during the Ice Age. The volume dimensions of the second type in round numbers are 100 times of the volcanic terrace and 1000 times of the earthflow terrace in the surrounding area. For the forming and retaining of the accumulation terrace a gorge might be needed in downstream site of the terrace acting as a dam.The former two examples have the both types of the terrace, and the latter has the first type only providing a vast alluvial valley flat being presumably a buried accumulation terrace.
日本第四紀学会の論文