충주분지의 지형분석 ( 퇴적물 분석을 중심으로 ) = Morphological Analysis in Chungju Basin ( Based on Deposits Analysis )

다국어 초록 (Multilingual Abstract)

This study is to clarify morphogenesis and development of landforms in Chungju basin by means of grain size analysis, the survey of the outcrops and petrographic comparison of sands and rocks. I surveyed and described deposit horizons, profiles of each .horizon, the meeting of bedrock and deposit on it, weathering rind, thickness of each horizon, form of soil grain, form of pore space distribution, sorting and bedding of deposits and drew columnar section of the outcrops in the survey of the outcrops. I analyzed the roundness and flatness in rock analysis and analyzed mineral composition, roundness and surface state of sand. I plotted histogram and cumulative grain size distribution graph and various graph by method of Friedman. Behind mountains, piedmont surface, river terrace, floodplain and river were developed in Chungju basin. Bedrocks were laminar weathered, floodplain and prototerrace were developed in Chungju basin which are two step terrace in form and are three step terrace in soil colors. After this basin was first denudated by base level following falling of sea level and upheaval of Mt. Taeback, this basin was deposited by rising sea level and temporary base level rising. Then this basin was deposited on it by mass movement. By the result of rock analysis roundness of rocks are high and flatnesses are low. Because rocks in this basin were transported in long distance by Namhangang & Dalcheon and there were a few local contribution. Or Fluvial energy of these river is high in concentric heavy rain There are many boulder and cobble on riverbed, coarse deposits on natural levee but smaller than those of riverbed. The grain size decreases with increasing distance from the stream. This was laterally and vertically deposited each one. The mineral composition of sand are various, that is, quartz(77%), orthoclase(2%). biotite(11%), muscovitet5%), basic rock(5%). Mineral spectrum of the sands reveals that granitic saprolite of basins is actually important furnishing source of river sand. Rounded sand and unround sand are mixed scattered. This reveals that sands are transported in long distance and sands are newly furnished Exoscopy of sand grains shows diverse rounded forms and variable surface feature, due to mixing long distance transported sand by Namhangang & Dalcheon and short distance transported sand from behind mountains and piedmont surface.