호남평야와 논산평야내의 충적평야 주변에 분포한 저구릉의 토양지형학적 연구 = A Pedogeomorphological Study on the Low Hills around the Alluvial Plains of the Honam and Nonsan Plains

다국어 초록 (Multilingual Abstract)

In the Korean peninsula, low hills, together with alluvial plains, constitute an important geomorphic element in larger plains such as the Honam and the Nonsan (Fig.1). This study attempted to elucidate their types in a pedogeomorphological viewpoint, based on their forms and associated soil covers. The main results obtained by this study are as follows: 1. The low hills are classified into Residual hills, Low relief erosion surfaces, Piedmont geomorphic surfaces, the Fluvial Surface 1 and Fluvial Surface 2(Fig. 3). 2. Residual hills and Low relief erosion surfaces are inferred to be formed in course of the decomposition and denudation of bedrock blocks. Piedmont geomorphic surfaces are supposed to be the lateral erosion surfaces of mountain streams around the boundary between mountains and the low relief erosion surfaces, which was also the contact of heterogeneous rocks(Fig. 2). But the low relief erosion surfaces and piedmont geomorphic surfaces were in the Korean Peninsula identified with pediments. This identification may need to be reevaluated. 3. The Fluvial Surface 1 and 2 are identified with thalassostatic terraces(or alluvial terraces) which were formed during the Climax period and the late of the Last Interglacial, respectively, on the basis of their sedimentary facies, distributions around the present tidal zones and the correlations to terraces in eastern coastal area of Korea. 4. The differences between the Fluvial Surface 1 and 2 are as below: 1) The Fluvial Surface 1 is remarkably eroded, and Red Soil developed on it. 2) The Fluvial Surface 2 is weakly dissected, and Brown Soil only on it. As these differences are the appearances which have been influenced since the dry land, a weakly developed Red Soil on the Fluvial Surface 1 indicates that this Surface had experienced the last rubefication during the latter half of the Last Interglacial. So that, the Red Soils in the Korean Peninsula are paleosols, they may be used as a stratigraphic marker. A tentative soil catena on the low hills is proposed(Fig. 5), applying the detailed soil maps(1/25,000) of this area(Fig. 4) and the stratigraphic sequence correlations between the landforms and soil types. 5. The piedmont geomorphic surfaces, the Fluvial 1 and 2 Surfaces are well preserved on the low hills around the Nonsan Plain, but are weakly around the northern part of the Honam Plain. Those differences are because of the quartzite gravel deposits as `gravel capped surfaces`, which were transported from the mountains. It is partly concluded that the differences of the low hills between the Honam and Nonsan Plains are attributed to the hard rocks-quartzites or sandstones etc.-which are in the source regions or not.