• Journal of The Geomorphological Association of Korea
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• v.23 no.2
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• pp.47-59
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• 2016

The formation age and depositional environment of the marine terrace I of the estimated paleoshoreline altitude of 18m in Sanhari of Ulsan coast, southeastern Korea were investigated on the basis of examination of lithofacies and stratigraphy of terrace deposits. Marine deposits of the terrace is composed of rounded boulders(70cm in diameter) and rounded pebbles(1.0cm in diameter) which overlay them. The above rounded boulders which lie on the paleo-shore platform are considered to have been formed by wave abrasion in the same period that the paleo-shore platform was developed. The rounded pebbles which lie on the rounded boulder layer are considered to have been deposited in gravel beach and berm environment, judging from the laminae developed in this layer. The paleo-shore platform and marine rounded gravel layer of the terrace are assumed to have been formed in the large transgression period of the Last Interglacial culmination stage(MIS 5e), judging from the comparision of the formation age of 125ka B.P. of Juckcheon terrace I in the adjacent Pohang coast which was dated by amino acid dating. The terrestrial deposit of this terrace was largely composed of angular and subangular gravel mixed with marine rounded pebble which has been carried away mainly from the deposit of previous marine terraces and redeposited in this terrace. The lowest peat layer of terrastrial deposit was considered to have been deposited during the period from the late MIS 5e which is the estimated finishing time of deposition of the above marine gravels to the early stage of following regression period(MIS 5d) in which the sea level was still high. The sediments of angular and subangular gravel deposit which lie on this peat layer were assumed to have been deposited during the period from the early stage of the first regression period(MIS 5d) of the Last Interglacial to the Last Glacial. The lower part of the angular gravel layer is composed of the deposits of the fluvial and colluvial sediments, whereas most of the upper and middle part of the layer is mainly composed of angular gravels of colluvial sediments formed in the cold environment.

• Journal of The Geomorphological Association of Korea
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• v.23 no.1
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• pp.17-33
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• 2016

Samples from newly exposed outcrop of sedimentary layers forming Jeongdongjin coastal terrace in Gangreung area are collected and analyzed to find the sedimentary environment. The site are located at the gentle hillslope of the terrace surface area. The height of the outcrop is about 8m and the altitude of it's highest part is 68~73m MSL. The lowest part of this out crop is the partly consolidated sand layer with gravel veneer within it. It is found that this part is not in-situ weathered sand stone through the OSL method. This sand layer is overlain by the gravel layer with sand matrix. The shapes of the gravels from this part are mainly 'platy', 'elongated', and 'bladed' by the index of Sneed and Folk(1958). In addition, mean roundness is not so high. It is sceptical to regard this part as marine sediments which are continuously exposed to erosional processes. The boundary between the lowest sand layer and gravel layer showing the abrupt change in forming material without any mixture or transitional zone, so gravels are seemed to deposited after some degree of consolidation of the lowest sand layer. In addition, the hight of the boundary between layers are changed by the place, so the surface of the partly consolidated sand layer is not flat and has irregularity on topography when it buried by gravels. Main part of this out crop is the poorly sorted coarse gravel(22.4mm) with sand matrix($1.36{\phi}$) layer with at least 2m thick covering the relatively fine gravels discussed above. Over 20% of particles have 'very platy', 'very elongated' and 'very bladed' shape and only less than 5% of particles have 'compact' shape, So this particles are also very hard to be regard as marine gravels which are abraded by marine processes. It can be concluded that this gravel layer formed by fluvial processes rather than coastal processes base on the form of the clast and sedimentary structure. The gravel layer is covered by fine($3{\sim}4{\phi}$) material layers of psudo-gleization which showing inter-bedding of red and white layers. Chemical composition of matrix and other fine materials should be analyzed in further studies. It is attempted to fine the burial ages of the sediment using OSL method, but failed by the saturation. So it can be assumed that these sediments have be buried over 120ka.

• Journal of The Geomorphological Association of Korea
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• v.25 no.4
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• pp.63-75
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• 2018

The lower marine terrace 1 and 2 surfaces distributed between Ulsan and Pohang coast in the southeastern coast of the Korean penninsula have been correlated with MIS 5e and 5a (or 5c) by amino acid dates, 14C dates, wide-spread tephra correlation and pollen analysis respectively. In this study, to test the reliability of the OSL method for the estimation of the numerical burial age of marine sediment deposits, we analyzed the samples from the marine terraces which have been known as typical marine terraces formed during MIS 5e and MIS 5a in the above-mentioned coast. The burial ages of the marine deposit of the lower marine terrace 1 and 2, with paleoshoreline altitudes of 18m to 19m and 10m to 11m respectively, both showed about the same age of 60 ka BP. The lower marine terraces 1 and 2, however, were divided into two terrace surfaces by a clear terrace cliff. Besides, the OSL dates of the lower and upper parts of the lower marine terrace 2 of the Bonggil coast showed the reversed burial ages. In the lower marine terrace 1 of the Sanhari coast, almost the same burial ages were derived from both the lower part (marine rounded gravel layer) and the upper part (terrestrial angular gravel layer) of the terrace deposit. Therefore, at the present time, judging from only the OSL dates measured in this study, it could be argued that the OSL method is not the best for the estimation of forming periods of the lower marine terraces 1 and 2 and their classification.

• The Korean Journal of Quaternary Research
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• v.4 no.1
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• pp.41-57
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• 1990

Gravel shapes of the terrace gravel sequences are compared with the present river gravels and beach gravels in the Pohang and its surrounding areas. Seventeen gravel textural parameters are divided into 5 groups based on R-mode factor analysis. Among them, three parameters (RDm, MPSm, SZstd) are selected for a test of discriminant possibility of palaeoenvironment of the terrace gravel deposits. Marine gravels are in the range of 0.49 to 0.75 in mean roundness, 0.46 to 0.78 in mean maximum projection sphericity and 0.39 to 1.85 in standard deviation of size, whereas river gravels are 0.28 to 0.51 in mean roundness, 0.66 to 0.72 in mean maximum projection sphericity and 1.04 to 1.81 in standard deviation of size. For practical access to the palaeoenvironment discrimination, a bivariant diagram between mean roundness and mean maximum projection sphericity is the most effective. The marine terrace gravels are plotted within the variation range of present beach gravels and show 0.49 to 0.71 in mean roundness and 0.59 to 0.66 in mean maximum projection sphericity. The gravels of river terrace vary within the range of gravels derived from present river bed and are characterized as 0.36 to 0.48 in mean roundness and 0.66 to 0.71 in mean maximum projection sphericity.

• Journal of The Geomorphological Association of Korea
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• v.20 no.1
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• pp.57-74
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• 2013

Coastal terrace was developed at 8.3m height near Waon village in Suncheon-si. Due to the sandgravel layer deposited in a different today's environments, rounded gravel(4.3m, 5.8m, 6.3m) sequentially in a cross-section of coastal terrace, so it provides a good example which understand Holocene sea level changes to determine the effect on the various climatic-environments traits. For the purpose of identifying the morphogenetic process, Profile description, Grain size, XRD, Thin section analysis was attempted. As a result, coastal terrace are more likely to have been formed by the more recent period rather than the last interglacial(MIS 5 period), and at that time, various pedological features are considered to be formed.

• Proceedings of the Korean Quaternary Association Conference
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• 1990.08a
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• pp.65-65
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• 1990

No abstract, See Full-text

• Journal of The Geomorphological Association of Korea
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• v.26 no.4
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• pp.21-31
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• 2019

Timing of terrace formation is a key information for understanding the evolution of fluvial systems. In particular, dating strath terrace (i.e. timing of terrace abandonment) is more difficult than depositional terrace that is conventionally constrained by radiocarbon, OSL and other dating methods targeting samples within terrace deposit. Surface exposure dating utilizing cosmogenic ¹⁰Be provides more reliability because it can be applied directly to the surface of a fluvial terrace. Thus, this method has been increasingly used for alluvial deposits. As well as other geomorphic surfaces over the last decades. Some inherent conditions, however, such as post-depositional ¹⁰Be concentration (i.e. inheritance), surface erosion rate, and density change challenge the application of cosmogenic ¹⁰Be to depositional terrace surface against simple bedrock surface. Here we present the first application of ¹⁰Be depth profile dating to a thin-gravel covered strath terrace in Korea. Monte Carlo simulation (MCS) helped us in better constraining the timing of abandonment of the strath terrace, since which its surface stochastically denuded with time, causing unexpected change of ¹⁰Be production with depth. The age of the strath terrace estimated by MCS was 109 ka, ~4% older than the one (104 ka) calculated by simple depth profile dating, which yielded the best-fit surface erosion rate of 2.1 mm/ka. Our study demonstrates that the application of ¹⁰Be depth profile dating of strath terrace using MCS is more robust and reliable because it considers post-depositional change of initial conditions such as erosion rate.

• The Journal of Engineering Geology
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• v.10 no.2
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• pp.133-149
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• 2000

The study area which contains the coastal terrace of the southeastern part of Korean peninsula, well developed the lineaments which are NNE, NE and WNW directions. The area crops out Cretaceous sedimentary rocks and granite porphyry, Tertiary conglomerate, tuffite and basalt and Quarternary deposits. Coastal terraces are subdivided into low, middle and upper terraces(LT, MT, UT) based on the topographic levels. Terrace gravels are deposited on these wave-cut erosional surface during the initial lowering stage of sea level fluctuation. Terrace gravels are typified by granule to pebble layers with slightly inclined beddings. These gravels are interpreted as beach gravels belonging to berm or swash zone based on the present distribution of beach gravels. The Suryum fault is characterized by the thrust which is gradationally changing the strike from ENE to NNE. The extension of the fault is about 200m and Maximum displacement is about 1.5m.

• Journal of The Geomorphological Association of Korea
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• v.18 no.1
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• pp.101-112
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• 2011

Coastal terrace was developed at 7.2m height near Shinchon village in Geoje Island. It is located on the east side of southern coast in Korean Peninsula, where sea-level changes caused by ebb and flow of the tide, embayment are relatively low. Due to the breccia layer by mass-movement, dark grayish clayey formation, marine origin's rounded gravel are deposited sequentially in a cross-section of coastal terrace, so it provides a good example which understand Holocene sea level changes to determine the effect on the various sedimentary environments. For the purpose of identifying the morphogenetic process, Grain size, Roundness, XRD, AMS dating analysis was attempted. As a result, after last glacial age, Holocene sea level rise to +5.6m(4,740±100yrs BP). At that time, various geomorphological features are considered to be formed.

• Journal of the Korean Geographical Society
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• v.44 no.4
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• pp.463-480
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• 2009

The weathering properties and provenance of loess-paleosol sequence deposited on gravel layer of river terrace in Bongdong-eup, Wangju-gun, Jeonbuk Province are examined using soil analysis, magnetic susceptibility measurement, grain size and element analysis. The Bongdong section consists of, from top to bottom, Layer 1(paleosol), Layer 2(loess), Layer 3(paleosol) and the gravel layer of river terrace. The magnetic susceptibility values show the systematic variations in the sequence and the results of grain size analysis reveal that the sequence was deposited by not fluvial or slope process, but eolian process, and that contains finer materials than the Daecheon loess and Chinese Loess Plateau. Among the results of soil analysis, organic contents indicate systematic variations similar to the magnetic susceptibility. The wet soil colors further reflect the characteristics of the sequence rather than the dry soil colors. Based on the analytical results of major and rare earth elements, the eolian materials contained in the sequence were deposited by the materials originated from the areas where the Chinese Loess Plateau has been originated or the reworked materials from the Chinese Loess Plateau, and after the depositions, the materials experienced the intensive chemical weathering under the humid-warm climatic conditions in the Korean Peninsula.