四国吉野川下流右岸の地形

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概要

• 論文の詳細を見る

• Investigating the river terraces and fault morphology on the right side of the lower Yoshino, the writer has come to the following conclusions. 1. The river terraces in this area may be classified into three groups: higher (H), middle (M). and lower (L). They may be further subdivided into H1, H2, H3; M1, M2; L1, L2, L3. 2. For the correlation of terraces, a comparative survey was effectively made as to the degrees of weathering of the terrace gravels and of laterization of their matrix as zonal soils. For example, the matrix of the higher terraces has the color in 1OR to 5YR (after Munsell's Color Chart) and that of the lower terraces in 7.5 YR to 2.5 Y. It may be presmned that the above methods can be applied to the correlation of the terraces in the Sanbagawa Terrain of the outer zone of the southwestern Japan. 3. The longitudinal profile of the terraces and the main river bed suggests an upheaval of about 20-40m in the western area. It will presumably represent a crustal movement of anticlinal axis connecting the center of the Asan Mountains with the Muroto Cape. The above figures, however, are not exclusively of the upheaval, but contains partly the effect of the accumulation from the tributaries. 4. The percentage of numbers of the outcrops including the sandstones from the Asan Mountains is higher at the middle and lower terraces than at the higher terraces. This may be attributed to the fact that the Asan Mountains probably elevated during the formation of gravel beds on the middle terraces. 5. The discovery of Kamiura Fault at the right side of the Yoshino confirmed that the eastern valley floor plain of the Yoshino is a graben between the Fault and the Median Line of its left side. The western part of the valley of the Yoshino is not a graben but an erosional valley along the Median Line, or a fault line valley. 6. The greater part of the higher flat surfaces north of Mount K6tsu may be considered a dissected fan supposeed to have been built by the activity of the Fault north of Mount kotsu. 7. Both Kamiura Fault and the Fault north of Mount Kotsu show the horizontal displacement measured about 40m at Kamiura Fault, and it is similar to the displacement of the Median Line (Kaneko 1966).

• 地理科学学会の論文
• 1967-10-15

著者

• 寺戸 恒夫

  阿南高専

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• 四国山地の陵線付近にみる特色ある地形について
• 大規模崩壊による山地地形の変化
• 四国吉野川下流右岸の地形

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