• Journal of The Geomorphological Association of Korea
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• v.27 no.4
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• pp.41-51
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• 2020

The Cheolwon-Pyeonggang Lava Plateau on the Chugaryeong tectonic valley is one of the most extensive volcanic areas in central Korea. However, formative age and process of the plateau still remains a controversial issue. This study presented OSL ages on the upper and lower sedimentary layers of basalt from four sites in the Cheolwon and Yeoncheon areas and estimated age and process of plateau formation based on sedimentary- and chrono-stratigraphy and topographic analysis. The results suggested that most of the initial topography of the plateau on the Cheolwon and Yeoncheon areas had been almost completed before approximately 90 ka. However, the last lava flow around Jangheung-ri, Cheolwon, seemed to occur until 20-30 ka and had led to complete the present plateau, while the last lava flow in the Jeongok area, Yeoncheon, was estimated to occur at approximately 40 ka.

• Journal of The Geomorphological Association of Korea
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• v.26 no.1
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• pp.93-106
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• 2019

The Yangsan Fault is one of the main fault systems in the Korean peninsula. It can be divided into three segments (northern, central, and southern) by its paleoseismic and structural geologic properties. Based on the geomorphic features of the northern segment, which includes the Yugye Fault, we identified deflected streams as a geomorphic marker of strike-slip component of the fault, and knickpoints along the streams as evidence of dip-slip component of the fault. Geomorphic analyses showed that (1) the horizontal displacements of deflected streams decreased and (2) the retreat amounts of knickpoints tend to increased toward north along the lineament. We interpreted the variations caused by strain partitioning; that is, there might be some increases of the vertical component toward north, whereas the main strike-slip fault system dies out, splaying into horsetail structure toward north. Based on the response time of the landforms, these interpretations imply that (1) there were differences between horizontal slip rate and vertical slip rate along strike, and/or (2) there were different timings between horizontal and vertical deformations by fault.

• Journal of the Korean association of regional geographers
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• v.15 no.4
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• pp.494-509
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• 2009

If teachers should showed geomorphological landscape images familiar to students during geomorphology unit teaching in secondary geography education, it will have more effects on teaching. In this paper, we analyze whether teaching of geomorphology unit using media(movie, drama, entertainment program) background images familiar to students have an effect on understanding of teaching facts and interesting or not. Firstly, teaching using media data is effective in understanding of teaching facts and the results of examination taken after teaching improved. Secondly, teaching using media data is effective in interesting and understanding on geomorphological landscapes. Most students recognized this teaching method to be new and became to be interested in learning geomorphology unit, and answered that it was helpful to understand geomorphology unit.

• Journal of The Geomorphological Association of Korea
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• v.27 no.2
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• pp.81-97
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• 2020

Geopark refers to a single boundary area consisting of a collection of geosites and geotrails, which includes ecological, historical and cultural elements based on geological and geomorphological resources. To ensure the continued development and conservation of existing listed geoparks, it is necessary to carry out an environmental sensitivity analysis of the geopark components by utilizing spatial information from various scales. The objectives of this study are to analyze the environmental sensitivity in Cheongsong UNESCO global geopark in relation with slope disaster using GIS and to understand its spatial distribution in connection with geosites and geotrails. Two types of spatial database were constructed; geosites and geotrails in Cheongsong UNESCO global geopark and spatial data to perform environmental sensitivity. Potential soil loss and slope stability were analyzed to derive environmental sensitivity related to slope hazard. The results showed relatively high environmental sensitivity along the drainage network of Cheongsong UNESCO global geopark. Zonal statistics analysis was conducted for further detailed distribution of environmental sensitivity based on buffer zones of geosites and geotrails. Majority of geological sites, geological trails, Jeolgol gorge~Jusan Pond section in hiking trails, and Dalgi Mineral Spring Site~Artistic Genius Republic of Korea(Jangnankki gonghwaguk) section in road areas show relatively high slope hazard sensitivity within buffer zones.

• Journal of The Geomorphological Association of Korea
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• v.21 no.4
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• pp.53-67
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• 2014

This study aims to develop and operate education program for the region-focused field study on the physical geography for the students to understand their community places in the geography classes of elementary and, secondary schools and college. The theme of the program is understanding the geomorphic structures and processes including river channel, wetland, levee, terrace, sand and gravel bar and alluvial island, floodplain and irrigation system in Miho river basin, Chuncheong Province of Central Korea. For the study of regional geography as their community, the field education is focused on relations of landform to everyday life, though different levels in learning achievement according to each school classes. But, the purpose of the field education is, same at all classes, for student to analyze and understand the geomorphic effects on the place of everyday life in geography education.

• Journal of The Geomorphological Association of Korea
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• v.18 no.2
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• pp.65-80
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• 2011

This is to find out geomorphological environment of optimum location for the object of dwelling site of Bronze Age (hereinafter called dwelling site) of total 177 unit confirmed in Yongducheon basin and Onyangcheon basin (hereinafter called investigation-object basin) in Asan-si Chungnam. To do this, hill of investigation-object basin where dwelling sites were confirmed was divided into 11 units of hillslope geomorphological and this was combined with the grade of 5 units of gradient and again subdivided into total 55 units of micro-landforms of Hillslope. Based on this, in the viewpoint of 'gradient of each of micro-landforms' analyzed 'number of dwelling sites' and 'dwelling site distribution density (unit: number of dwelling sites/1000m2)'. As the result, the optimum geomorphological environment where dwelling sites were located was largely confirmed be 5 units(① semi-gentle slope land of crest slope ②gentle slope land of crest slope ③ slope of upper sideslope ④ flat land of crest slope ⑤ flat land of crest flat). It is thought that this analysis data will be used in the future as basic data for the study of predicting distribution of dwelling sites in Bronze Age which might have been buried in the investigation-object basin.

• Journal of The Geomorphological Association of Korea
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• v.19 no.1
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• pp.99-108
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• 2012

To consider geomorphological and geological characteristics to Gatbawi(the 500th natural monument), it was investigated with the aspect of scale, form, mineralogy, chemistry and weathered state. Showing typically erosional features, micro-terrains as sea cliffs, sea notches, marine plateaus and tafoni developed well on coastal areas near the monument. Sea cliffs are vertical and form sea notches in their bases. Coastal terraces are 3.5m in width and 20m in trace. Tafoni are honey combed. The monument is mainly composed of quartz, plagioclase, microcline, biotite, sericite in mineral and corresponded to crystalline tuff dominated in quartz and plagioclase. It has 23.60~28.27 wt.% of $Al_2O_3$, 3.27~5.80 wt.% of $Na_2O$, and 0.11~0.20 wt.% of Cl in chemical contents, leveling higher than those of earth crust standards. It is considerably weathered on the basis of CAI(77.42~83.93%). The monument is very useful for natural perspective tourism and education. Therefore, it is necessary that several ideas as guide plates, observing telescope, explaining guider, education programs connected with related services, touring goods, picture for books on utilization on the monument must establish.

• Journal of The Geomorphological Association of Korea
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• v.25 no.3
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• pp.19-42
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• 2018

In this study, we surveyed weathering progressing aspect by major elements variation and rock hardness by using XRF analysis, schmidt hammer, and thin section analysis. This observation suggested that the weathering process is likely to develop differently according to microstructural characteristics. R-value on the inside wall are lower than those on the outside. Also, the shadier the environment was, the closer it was to inshore areas, the R-value appeared to be lower. The movement of the elements such as Ca, Na and K shows that feldspar is hydrolyzed and can form salt crystallization like a gypsum or halite when they combine with the elements such as S or Cl. It proved a high CaO, $Na_2O$ and $K_2O$ content on flaking inside wall and rock meal. The exfoliation was mainly observed along the shady backwall and ceiling of tafoni. This helped in predicting the growth of tafoni as well as the direction of its progress.

• Journal of The Geomorphological Association of Korea
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• v.28 no.2
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• pp.59-70
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• 2021

This study aims to determine the sunlight exposure according to depositional environment to improve the accuracy of optically simulated luminescence (OSL) dating. Sufficient sunlight exposure during transportation of sediment is a basic assumption of the OSL dating, and if the process does not occur enough, the results may be overestimated compared to the actual depositional age. Therefore, the main purpose of this study is to establish a correction method by determining residual or unbleachable dose after sunlight exposure in the actual deposition process, not in the laboratory measurement. Four samples from two sites were collected according to the depositional environment from rivers and coasts, and various OSL signals, including the size of residual dose, degree of dispersion between grains, and OSL signal sensitivity, were measured. As a result, it was confirmed that sediments formed under temporarily high energy environments, such as floods and surges, had relatively high residual dose or large dispersion of residual dose between particles. In further studies, the OSL signal characteristics of river sediments by flow velocity will be identified and the relationship between energy and OSL signal characteristics will be identified in more detail. Moreover, a method of reconstructing the paleo-environment at the time of deposition for existing sediments will be devised. It is expected to provide important information for the frequency of disaster recurrence and prediction of future climate change.

• Journal of The Geomorphological Association of Korea
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• v.28 no.3
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• pp.27-35
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• 2021

This study tried to reveal incision rate and its change by formation of lava plateau in the Cheorwon-Jeongok area. Incision rates of 0.421 m/ka and 0.101 m/ka in the upper and lower reaches of Hantan-gang, respectively, were calculated from sites before formation of lava plateau. These incision rates indicate that the upper and lower reaches of Hantan-gang have much higher and slightly lower incision rates than streams with similar distances from the Taebaek Mountains. However, sites after formation of lava plateau mostly showed incision rates ranging from 0.5 m/ka to 0.9 m/ka. Streams flowed on the lava plateau revealed 2-3 times higher incision rates than unrelated-streams or paleo-streams to formation of lava plateau did. These results suggest that incision rate in the study area was greatly influenced by formation of lava plateau and resultant geomorphic avulsion with rearrangements of stream.