• Journal of The Geomorphological Association of Korea
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• v.26 no.1
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• pp.59-78
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• 2019

The physical and chemical characteristics of more than 5 m sandy deposits behind the beach in Sinji-do Island are investigated and its burial ages are estimated using Optically Stimulated Luminescence. By the estimated burial ages of the sandy deposits, this section is divided into four sub-units: Unit I (6.2 ka), Unit II (23.2 ka), Unit III (115.9 ka), and Unit IV (115.9 to 127.5 ka). It can be proposed that the Unit I of a coarse sand deposited during the Holocene Climatic Optimum. Unit II, supposed to be the aeolian sediments, formed during the Last Glacial Maximum (LGM). It can be supposed that the study area was not affected by the marine processes during the LGM, directly. Unit III is more consolidated deposits of coarse silt to fine sand and deposited during the Last Interglacial Period. Unit IV mainly consist of beach gravels with sandy matrix deposited during the Marine Isotope Stage 5e (MIS 5e), and thus indicates that the sea level of the southwest sea had risen 3 to 5 m above present sea level during the MIS 5e.

• The Korean Journal of Quaternary Research
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• v.17 no.2
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• pp.15-15
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• 2003

In South Korea, marine terraces have been well developed along the eastern coastal zone, and previous researches on the marine terraces have also been focused on to this coastal zone. The marine terraces of the eastern coast of South Korea had been classified into three terrace groups, that is, the higher, middle, and lower surface ones, according to the heights of marine terraces by previous studies(Oh, 1981 ;Chang, 1987 ;Yoon et. al, 1999, 2003 ; Hwang and Yoon, 1996 etc.). Recently, however, it tends to classify the marine terraces based on the concept of geomorphic surface units(Lee, 1987 ; Kim, 1990 ; Choi, S. 2003; Choi S. et. al 2003a,b, etc). For example, it was proposed that the marine terrace surfaces of Eupcheon coast of the southeastern coastal area of Korea could be classified into 16 geomorphic surfaces, i.e., Eupcheon 1terrace(former shoreline height of 160m), 2(153m), 3(140m), 4(130m), 5(124m), 6(115m), 7(100m), 8(92m), 9(82m), 10(71m), 11(62m), 12(53m), 13(43m), 14(35m), 15(18m) and 16(10m) surfaces, in descending order, according to the former shoreline heights(Choi, S, 2003 ; Choi, S. et. al, 2003a,b). Among these terraces, Eupcheon 1, 2, 4, 5 and 7 surfaces had not been reported in previous works. Among the above mentioned marine terraces, Eupcheon 15 terrace, the most widely and continuously distributed marine terrace have been identified as marine terrace of the Last Interglacial culmination period(oxygen isotope stage 5e) which was based on amino acid dates(124∼125ka BP) and geomorphological features such as red soil, pollen analysis, fossil cryogenic structures and crossing terrace concept. Eupoheon 15 terrace surfaces have also been proposed as the key surface for the identification and correlation of the so-called '5e' marine terrace in the eastern coast of South Korea. This terrace was reconfirmed as the Last Interglacial culmination period, which was based on the identification of Ata tephra, one of the wide-spread marker tephra which indicates the Last Interglacial culmination period in Japan by Sasaki et. al(2002). It was thought that marine terraces of the eastern coast of South Korea had been formed by the steady-state uplifting during the Quaternary glacio-eustatic sea level changes(Choi, 1997). The uprift rate of 10cm/1,000years had been proposed in the eastern coast of South Korea based on the former shoreline altitude(18m) of the above Eupcheon 15 terrace. Therefore, it can be estimated that Eupcheon 1 terrace had been formed in the early Pleistocene from the above uprift rate. The OSL dating for the samples of Eupcheon 7, 9, 13, 15 and 16 terraces and identification of marker tephra in the terrace deposits are in progress. It is expected that more elaborate chronology on themarine terraces of the eastern coast of South Korea could be established by these absolute dates and marker-tephra.

• Journal of the Korean earth science society
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• v.26 no.5
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• pp.443-458
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• 2005

Late Quaternary deposits of the core in the western area of the Nakdong River delta consist of four sedimentary units: Unit I, II, III and IV, in ascending order, controlled by the sea-level change since the last interglacial period. Unit I unconformable overlying Cretaceous basement rocks is composed of sandy gravel and sand deposited in a fluvial channel before the first marine transgression. Unit II composed of stiff massive mud is interpreted as a shallow marine deposits formed during the last interglacial period (probably MIS 5). The development of the fissures coated with oxidized materials in the upper part of Unit II is a feature of subaerial exposure, which indicates erosional contact with the upper Unit III. Unit III is made up of soft massive mud and soft shelly massive mud deposited in a tidal flat and a inner shelf, respectively, since the Holocene transgression (about 9,000 yr BP). Unit Ⅳ consisted of soft shell bedded mud and yellowish sandy mud was deposited in the delta environments during the regression (after about 5,000 yr BP). The lower shell bedded mud was deposited in a tidal flat and the upper sandy mud was deposited in the floodplain corresponding to present site of the Nakdong River delta.

• Journal of the Korean Geographical Society
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• v.38 no.4
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• pp.505-517
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• 2003

The purpose of this paper is to examine the origin of materials of sanddune in the Chungcheongnamdo. The sands consist mainly of quartz with lesser amount of feldspar and other heavy minerals. With the exception of those from the granite, the sands have a very fine texture. Another characteristic of the sand grains is the low degrees of roundness and grading which indicates that the source areas of the material are not far from the accumulating field. The rivers and streams of this region are not effective in transporting sediments for the coastal dunes. It has been recognized that the beaches and sanddunes have recently been receded as a result of the decrease in materials and the devastating actions of the breakers. The degradation process occurs most actively when the spring tides attack the beaches and foredunes. There are strata with red tint along the coastal areas of the Chungcheongnamdo which trace their origin back to the Pleistocene. From the fact that they contain little or no gravels, the strata are believed to have been the sanddunes during the last interglacial period. This fossil dunes provide part of the materials for the development of the present-day sanddunes along the coastal areas of the region.

• Journal of the Korean Geographical Society
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• v.38 no.2
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• pp.156-172
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• 2003

In this paper we identify that there are High Higher surfaces(HH-surface) around Jeongdongjin and Daejin area where Higher surfaces(H-surface) of marine terrace are formed on a large scale. On the basis of an altitude of the ancient shoreline of the marine terraces, geomorphic surfaces can be classified into HH I (140m a.s.l), HH II (110m a.s.l), H I (90m a.s.l), H II (70m a.s.l), M (40m a.s.l), L I (25m a.s.l) and L II (10m a.s.l). Besides, we identify that the lowest surfaces(5~6m a.s.l) are found extensively in the research area which are assumed to be formed in the Holocene. Considering that the formation mechanism of the marine terraces in the research area is similar to that of the marine terraces at both Campo area in the south east coastal region of Korea md the thalassostatic terraces of Osip River in Samchuk in a short distance from the research area, we can assume that the HH-surfaces in both areas were formed in the same period. Based on the fact that L I- surface was formed on the Last Interglacial Stage of MIS 5, we can infer that M- was formed in MIS 7, H I- in MIS 9, H II- in MIS 11, HH I- in MIS 13 and HH II- in MIS 15. The reason for that H-surfaces, similar to those at Gampo area, to remain on a large scale is that the Holsteinian Interglacial continued for a long period of time and at that time there was a large wave-cut platform in the vicinity of the shoreline.

• Journal of the Korean Geographical Society
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• v.31 no.3
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• pp.613-629
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• 1996

River terraces of glacial and interglacial periods are most developed in the Ungcheon River, midwestern coastal region of south Korea. Among these terraces, interglacial river terraces correspond to the thalassostatic terraces of eastern coastal region of Korea. Thus the former shoreline altitudes of the coastal region around Ungcheon River can be estimated by using relative heights of these interglacial thalassostatic terraces of Ungcheon River The former shoreline altitudes estimated from interglacial thalassostatic terraces of Ungcheon River are 80m, 50${\sim}$60m, 40${\sim}$45m, 30m, 25m(?), 15${\sim}$20m, and 10m. These estimates are almost identical with those of Quaternary sea levels of eastern coastal region. Among the above estimates of Ungcheon River, the former shoreline altituded of 15~20m and 10m correspond to the ancient sea levels of $\pm$18m and $\pm$10m of eastern coastal region which were injudged as the last interglacial culmination period and late warmer period of the last interglacia(5e and 5a substages of oxygen isotope stage), respectively. Therefore there is a possibility that the rest of the above former shoreline altitudes of the coastal region aroune Jngcheon River also correspond to those of eastern coastal region. On the basis of the above possibility it can be proposed that the eastern and western coastal region of Korean Peninsula have undergone tectonic uplift of equall amount since the middle Quaternary Period.

• The Korean Journal of Quaternary Research
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• v.11 no.1
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• pp.57-68
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• 1997

Climatic change of the late-Quaternary period has been record-ed in the loess deposits of the central Great plains and the record of such change is extractable using a number of approaches and parameters. The stratigraphy of loess deposits which have been investigated on Fort Riley exhibits the same sequence of loess units and intercalated buried soils as is found elsewhere in the re-gion but adds detail unique to the reservation Upland late-Qua-ternary composite stratigraphy preserved on the reservation con-sists of the basal Sangamon soil of the Last interglacial(c. 120-110ka), Gilman Canyon Formation(c. >40 -20ka), Peoria loess(c. 20 -10ka) Brady soil(c. 11 -10ka) Bignell loess(c. 9-\ulcornerka). and mod-ern surface soil. Application of magnetic analyses has provided proxy data sets that represent a time series of climatically regulated pedogenesis/weathering and botanical composition. magetic data have yielded an impression of the variation in climate from Sangamon time to the late Holocene through a reconstruction of the history of pedogenesis/weathering. Sangamon soil formation dominated the reservation durin the Last interglacial as indicated by magnetic parameters. During Gil-man Canyon time loess influx was usually sufficiently slow as to permit pedogenesis which appears to have been at a maximum twice during that time. Warm season grasses were important dur-ing soil formation but diminished in importance during the peri-ods of more rapid loess fall which were cooler and perhaps wet-ter. Peoria loess fall a function of the deterioration of climate during the last Glacial Maximum thinly blanketed the reservation with thickest accumulations occurring to the north-west(Bala Cemetery site)proximal to the source region. Long-term surface stability did not apparently occur within Peoria time but short-term stability may be indicaed by the presence of thin weathering zones(incipient soils) in the Peoria loess. Re-gional landscape stability prevailed during the environmental shift at the Pleistocene/Holocene transition resulting in forma-tion of the well expressed Brady soil. One or more weak soils developed in the Bignell loess as it ac-cumulated. A notable feature of the Bignell loess is the appear-ance of the Altithermal dry period: the loess experienced little weathering and was dominated by warm season grasses until the latter of the Holocene.

• Journal of The Geomorphological Association of Korea
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• v.26 no.4
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• pp.67-79
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• 2019

This study documents the level of paleo-shoreline and the timing of formation of the lowest marine terrace (1st terrace) distributed in Dadaepo, Busan, South Korea. In the study area, the elevation of paleo-shoreline of the 1st terrace is clearly identified as 5 meters above mean high tide based on the elevation of wave-cut platforms and the elevation of boundary between marine and terrestial sediments. This is well consistent with the fact that are found along the Southern coast of the Korean Peninsula including Daepo-dong, Sacheon-si. The timing of formation of the 1st terrace in Dadaepo is confirmed to have been deposited around 70,000~80,000 years BP (MIS 5a) according to OSL and IRSL dating ages. However, because the formation age of the 1st terrace in Sacheon-si Daepo-dong (Southerm coast) and Pohang-si Umok-ri (Eastern coast) previously identified as about 90,000~100,000 years BP (MIS 5c), further discussion of what is needed. Possibly, it can be interpreted that the sub-interglacial (MIS 5a and 5c) sea-level records during the last interglacial period are likely to be selective on land depending on regions.

• Ocean and Polar Research
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• v.41 no.3
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• pp.159-168
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• 2019

Understanding the interaction between climate and the water cycle is critical especially in a drought sensitive region such as California. This study explored hydrologic changes in central and southern California in relation to the glacial-interglacial climate cycles over the last 30 thousand years. To do this, we reconstructed paleovegetation using plant wax carbon isotopic compositions (${\delta}^{13}C$) preserved in marine sediment cores retrieved from the central California continental shelf (ODP Site 1018) and Santa Barbara Basin (ODP Site 893A). The results were then compared to the existing sea surface temperature (SST) and pollen records from the same cores to understand terrestrial hydrology in relation to oceanographic processes. The Last Glacial was generally dry both in central and southern California, indicated by grassland expansion, confirming the previously suggested notion that the westerly storm track that supplies the majority of the precipitation in California may not have moved southward during the glacial period. Southern California was drier than central California during the Last Glacial Maximum (LGM). This drying trend may have been associated with the weakening of the California Current and northerly winds leading to the early increase in SST in southern California and decline in both offshore and coastal upwelling. The climate was wetter during the Holocene in both regions compared to the glacial period and forest coverage increased accordingly. We attribute this wetter condition to the precipitation contribution increase from the tropics. Overall, we found a clear synchronicity between the terrestrial and marine environment which showed that the terrestrial vegetation composition in California is greatly affected by not only the global climate states but also regional oceanographic and atmospheric conditions that regulate the timing and amount of precipitation over California.

• Journal of the Korean earth science society
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• v.42 no.6
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• pp.677-687
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• 2021

In this study, we analyzed diatoms from core RS15-GC41 collected in Iselin Bank, Ross Sea. A total of 24 genera and 35 species of diatoms are identified, and the having valve abundance of diatoms varies from 0.2 to 28.6×10⁶/g. Four diatom assemblage zones are established by the vertical distribution of diatoms, and changed with a cycle of 100 kyrs. RS15-GC41 were deposited over the last 400 kyrs (corresponding to Marine Isotope Stages 1-11). The open-water species Fragilariopsis kerguelensis, Rhizosolenia styliformis, and Thalassionema nitzschioides abundantly occurred in interglacial periods. Whereas, Actinocyclus actinochilus abundantly dominant during the glacial periods. The distribution of these diatoms indicated, it can be seen that the sea-ice extent was larger and lasted longer during MIS 7, 9, and 11 than that of MIS 1, 3, and 5. Moreover, Paralia sulcata was abundantly predominant in MIS 7, 9, and 11; this finding suggests likely indicating that P. sulcata was transported from the coastal/inner shelf area to the study site, during accumulated in the sediments, reworked with the influx of ice-rafted debris by the currents