A STUDY ON THE MECHANISM AND CHRONOLOGY OF COLLUVIAL SLOPE FORMATION IN THE DRAINAGE BASIN OF THE SUGIHARA RIVER, THE SOUTHERN PART OF HYOGO PREFECTURE
スポンサーリンク
概要
- 論文の詳細を見る
The authors study on gentle slopes which are widely distributed at the foot of the low mountains in the southern part of Hyogo prefecture. These slopes with concave longitudinal profile are predominantly developed on the rhyolitic mountains. The results of this study are summarized as follow : 1. The gentle slopes consist of colluvial slopes which continue to alluvial fans toward downslope. 2. These colluvial slopes and fans can be divided into surfaces I to V in the descending order. The older surface is generally distributed with steeper slopes in the mountains. 3. The surface I was formed during the glacial age but one, the surface II during the last glacial age, the surface III mainly between the post-glacial age and approximately 6, 000 years ago, and then followed formation of the surfaces IV and V. 4. The surface I was formed at the base of slopes as a depositional surface with debris produced by the frost action in the cold period and by removing of these deposits due to solifluction and mud-flow. These deposits turned later into the red weathered crust in the interglacial age. The surface II was formed in the cold period of the last glacial age by the same mechanism as the surface I. The surface III is mainly fan with composed mud-flow deposits and formed between the maximum phase of the last glacial age and approximately the time of Jomon transgression in the post-glacial age. The surface IV and V were formed as fans mainly composed of deposits that re-moved from surface II and III in the later period of relatively mild and wet climate. 5. A series of these depositional surfaces are distinguishedly distributed on the rhyolitic piedmonts. This fact is considered to have been caused by the discontinuous disintegration of rhyolitic rock which forced in the production of a large amount of debris difficult to be re-moved. 6. The fractured zone in the rhyolitic areas seems to be closely related with the production of a large amount of debris. 7. The concave slopes of these piedmonts viewed from a distance are resulted from overlapping of the above-mentioned surfaces I to V. It can be concluded that the following factors are closely related all together to the formation of colluvial slopes in this area; the fractured rock by faulting, the peculiarity of the grain size of debris produced under the rock control at the time of disintegration, the difference in weathering and disintegration of rock, and the way of transportation of debris affected by climatic changes.
- The Association of Japanese Geographersの論文
The Association of Japanese Geographers | 論文
- The influence of irrigation system on salinity in surface soil of agricultural land in coastal area of the Red River Delta-Northern Vietnam
- Under Two Globalizations: Progress in Social and Cultural Geography of Japanese Rural Areas, 1996-2006
- Fault Geomorphology Interpreted Using Stereoscopic Images Produced from Digital Elevation Models
- What is Expected of Geography Education? : A Discussion Based on Interviews with those who Majored in Geography in College
- 中国雲南省拉市海周辺における乗馬観光の展開