十日町盆地の河岸段丘

概要

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There are distinct river terraces continuously observable along the middle and upper reaches of the Shinano River. These river terraces were grouped according to the extent of their growth into five areas, that is, Tsunan Right Bank of Tokamachi, Left Bank of Tokamachi, Southern Ojiya, Ojiya-Koshijimachi and Sekihara-Mishimamachi. Each area shows from four to eight terraces, which are correlative between all the areas or between the four of five areas. The terraces were considered to be formed in Late Pleistocene or Holocene except Taniage Terrace of Tsunan Right Bank of Tokamachi which was considered to be formed in Middle Pleistocene. The basement complex of the terraces was determined to be Uonuma Group, because the displacement and transformation characteristic of the folding structure of Uonuma Group are widely observed throughout the entire area. The Uonuma Folding Structure which developed concurrently with the growth of the river terraces exerted a great influence upon their development and displacement.
日本地質学会の論文
1972-12-25