해안 암체와 내륙 암체부의 풍화 와지 사이의 암석 강도 차이에 대한 연구
A study on the differences in chemical weathering intensity and rock strength between weathering pits of inland cliff and coastal rocks
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초록
The chemical composition of samples from abandoned cliff and coastal rocks at Munam, Gosung, Gangwon province are analysed. Weathering pits are found at the top and surface of abandoned cliff and these forms are inactive in terms of active physical and chemical weathering. So these forms can be regarded as relict forms rather than active. The tafoni and weathering pits are found from the coastal rocks which are actively being weathered and eroded by sea water and splash. The rebound values are measured at 5 points at and around the abandoned cliff with Schmidt hammer. The results show that the coastal rock has higher rebound values than abandoned cliff. It can be assumed that coastal rock is composed with more resistant rock than abandoned rock cliff. Weathering intensity of each samples can be compared with various weathering indices which can be calculated using chemical composition. In this study, the CIA, most frequently used index in geomorphological literatures, showed only weak difference between the samples. The CIA value of the coastal rock is lower than those of abandoned cliff. However, the difference between two groups is very small. PIA shows similar pattern while the WIP and CPA show similar patterns with larger differences. In the case of WIP, the value of coastal rock is highest and cliff and rock meal are follows. It means the coastal rock is most fresh in terms of chemical weathering while the rock meal is severely weathered. This pattern shows good match with rock rebound values. It is assumed that this pattern is not result of current weathering and weathered material removal processes which is most active near of the sea. It can be concluded that the abandoned cliff had experienced similar weathering environment to coastal rock. After it was abandoned, weathered part of the cliff experienced relatively slow erosion processes and preserve the weathered materials, while weathered part of coastal rock is eroded continuously by sea water and relatively fresh parts are exposed to surface. This results are support the result from previous study from the coast of Yellow sea.
Abstract
The chemical composition of samples from abandoned cliff and coastal rocks at Munam, Gosung, Gangwon province are analysed. Weathering pits are found at the top and surface of abandoned cliff and these forms are inactive in terms of active physical and chemical weathering. So these forms can be regarded as relict forms rather than active. The tafoni and weathering pits are found from the coastal rocks which are actively being weathered and eroded by sea water and splash. The rebound values are measured at 5 points at and around the abandoned cliff with Schmidt hammer. The results show that the coastal rock has higher rebound values than abandoned cliff. It can be assumed that coastal rock is composed with more resistant rock than abandoned rock cliff. Weathering intensity of each samples can be compared with various weathering indices which can be calculated using chemical composition. In this study, the CIA, most frequently used index in geomorphological literatures, showed only weak difference between the samples. The CIA value of the coastal rock is lower than those of abandoned cliff. However, the difference between two groups is very small. PIA shows similar pattern while the WIP and CPA show similar patterns with larger differences. In the case of WIP, the value of coastal rock is highest and cliff and rock meal are follows. It means the coastal rock is most fresh in terms of chemical weathering while the rock meal is severely weathered. This pattern shows good match with rock rebound values. It is assumed that this pattern is not result of current weathering and weathered material removal processes which is most active near of the sea. It can be concluded that the abandoned cliff had experienced similar weathering environment to coastal rock. After it was abandoned, weathered part of the cliff experienced relatively slow erosion processes and preserve the weathered materials, while weathered part of coastal rock is eroded continuously by sea water and relatively fresh parts are exposed to surface. This results are support the result from previous study from the coast of Yellow sea.
참고문헌 (32)
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