• Journal of The Geomorphological Association of Korea
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• v.17 no.1
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• pp.59-72
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• 2010

This study is based on the observation on the patterned ground found in the northern part of the Baekdusan during two fieldtrips of 2008 summer. The patterned grounds are found in two areas-Dalmun and Socheonji. The patterned ground found around Dalmun are well-sorted, having fine materials in the center and coarse (boulder size) materials in the rim, and stretching in the form of stairs. Meanwhile, the types of patterned ground found around Socheonji are various, including polygon, stripe, and circular patterns. The particle size analysis and morphological analysis of comprising materials are carried out only for the patterned ground of Socheonji. The mean short and long axis of the patterned grounds are 91cm and 163cm, respectively. The distribution pattern of material size from the most samples increase toward the rim, indicating the patterned grounds are well-sorted. The comprising materials are dominated by silt, which is very susceptible for freeze-thaw cycle. The lower ratio of clay (low less than 10%), suggests that physical weathering is more dominant rather than chemical weathering. The involution structure found in the vertical section of the patterned grounds is likely to have formed by active cryoturbation which is one of the dominant geomorphic processes in the periglacial environments like the study area.

• 한국해양학회지
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• v.29 no.1
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• pp.42-49
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• 1994

A series of radiocarbon dating from intertidal, subtidal, and inner continental shelf deposits investigated along the west coast of Korea as well as from its offshore sea floor (namely, the eastern Yellow Sea Basin) how (1) the Holocene sea level rise, i.e., the ecstatic sea-level history during the oxygen isotope stage 1, and (2) pre-Holocene sea-level fluctuations during the oxygen isotope stages 2 and 3. Marine geophysical investigations in the Yellow Sea reported a possible development of desert and loses deposits due to dieselization under the cold and dry climate during the Last Glacial Maximum. The Kanweoldo deposit overlain unconformably by the Holocene intertidal deposits, which is mainly exposed along the tidal channels and intertidal flats in the Cheonsu Bay, the west coast of Korea, shows the characteristic cryogenic structure (cryoturbation). Such cryoturbation structure of the Kanweoldo deposit appears to indicate the cold and dry climate under the ecstatic sea-level paleoshoreline standing before and after of the pre-Holocene interstitial period (about 30000 y BP is suggested and its shoreline curve is constructed.

• The Korean Journal of Quaternary Research
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• v.19 no.2
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• pp.40-43
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• 2005

The island alpine biogeography of Mt. Halla (Hallasan), Jeju Island (Jejudo), Korea is discussed. The presence of numerous species of alpine flora on Mt. Halla, the southernmost distributional limit for certain species, may primarily be attributed to palaeo-environmental factors, since it can not be wholly explained by reference to current environmental conditions. The alpine flora on the peak of Mt. Halla, mainly above 1,500m a.s.l, is evidently descended from immigrants from NE Asia via the Korean Peninsula during the epochs of the Ice Age. These plants, which are very intolerant of competition with temperate vegetation, have been able to persist in alpine belts thanks to their harsh climatic conditions, sterile soil, rugged topography and cryoturbation. The alpine plants on Hallasan are in a stage or process of retreat toward the mountaintop, most likely due to recent climatic amelioration. The lower limit of some species seems to coincide with maximum summer isotherms. The continued survival of arctic-alpine and alpine plants on the summit of Hallasan, Jejudo, the Korean Peninsula, however, is in danger, if global warming associated with the greenhouse effect continues.

• Journal of the Korean Geographical Society
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• v.36 no.3
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• pp.233-246
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• 2001

Topography and soil characteristics of earth hummocks are examined in the summit crater of Mt. Halla in order to evaluate their morphoclimatic significance as an indicator of a periglacial environment. The hummocks are generally oval in outline, and they have a diameter of 42 to 200 cm and a height of 9 to 27 cm Seventeen hummocks are distributed In a 5$\times$5 m quadrat at an interval of 20 to 40 cm Excavation reveals the cryoturbated soil profiles which consist of upper dark brown layer and lower brown layer. The dark brown layer has 61.8% total clay and silt content, implying Its high frost susceptibility Earth hummocks have the dry density of 0.761 to 1.009 g/㎤ the void ratio of 1420 to 2.008, and the moisture content of 24.2 to 68.8% by weight, respectively. The hummocky soils become compacted and desiccated downward. Earth hummocks are frozen as a hard solid mass during winter and early spring, and freezing fronts reach about 45 cm below their apices. The layer with high lute content appears in the upper horizon of dark brown soil. but Ice lenses are not so much segregated The moisture content of hummocky soils generally increases up to 73.9 to 118.80% for dark brown layer and 49.9 to 82.8% for brown layer during thins period Because the cohesive soil of earth hummocks indicates 72.8% of the moisture content as a liquid limit, the dark brown layer is highly fluid and consequently subject to cryoturbation processes.

• Journal of The Geomorphological Association of Korea
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• v.18 no.4
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• pp.177-191
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• 2011

This paper describes a dune field on shoreline of Young Gwang. To clarify geomorphic characteristics, made an analysis of grain size of the sand sediments samples and surface texture of quartz grains, and field survey. The following results were obtained : 1) Young Gwang sand dune is taking to pieces by human impact, and dose not move ahead the process of sand dune. 2) there was a turbulence of sand sediments outcrops saying to the cryoturbation that represents cold climatic environments, 3) Constituents of sand dune are mainly fine and very fine sand(2.5~4.5Φ) consisted by quartz and feldspar. Young Gwang sand grians have some analogy with different sites in west coast 4) In surface texture, roundness is thought to have been formed sub-angular, and some V cracks represented mechanical weathering environments. Especially, the dune environment has significant cultural and archaeological values arising from the occupation of human in the past. Those areas where occupation is known provide a valuable source of past records relating to human settlement.

• The Korean Journal of Quaternary Research
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• v.9 no.1
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• pp.43-60
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• 1995

The Kanweoldo Deposit in the Cheonsoo Bay western coast of Korean Peninsula is considered to be influenced by severe freezing condition under cold humid environment of the last glacial age. The evidence of severe freezing in the some upper part of the fine-grained Kanweoldo Deposit is characteristically irregular wavy la-mellar structure with the interval of 2∼8mm. In particular lamina show very compacted fabrics composed of rounded or spheroidal discrete aggregates covered by silt caps. Such laminar structure and associated micro-fabrics might owe to soil freezing such as ice segregation in lens form cryophoresis pressure from growing ice and disturbance by frost-creep. Furthermore pedogenesis of cold-humid type such as gleyzation or peseudo-gleyzation also might af-fect the kanweoldo Deposit in the priod of severe cold-humid cli-mate of the Wrm. The Kanweoldo sediment and organic remnant(16,708 B.P. with error limit of 250 years) affected by severe cryogenic activities sug-gest that the paleoclimate of Late Wrm in Korea might be so cold and humid as to engender the cryogenic structure in subaerial silty and sandy silt deposits.

• The Korean Journal of Quaternary Research
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• v.2 no.1
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• pp.25-50
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• 1988

The survival of rich evidence of palaeolithic occupation found in the Imjin-Hant'an River basin was possible due to many fortuitous geological conditions provided there. Formation of the basalt plain in a narrow valley system which developed during the late Mesozoic insured the appearance of a basin of sedimentation in which archaeological sites would be preserved with relatively minor post-depositional disturbance. Geomagnetic and K-Ar dating indicates that lava flows occurred during the Brunes Normal Epoch. During and after the process of basin sedimentation, erosion of the plain was confined to the major channel of the present river system which developed along the structural joints formed by the lava flow. Due to characteristic columnar structure and platy cleavage of the basalt bedrock, erosion of the basalt bedrock occurred mainly in vertical direction, developing deep but narrow entrenched valleys cut into the bedrock. Consequently, the large portion of the site area remained intact. Cultural deposits formed on top of the basalt plain were left unmodified by later fluvial disturbances due to changes in the Hant'an River base-level, since they were formed about 20 to 40m above the modern floodplain. Sedimentological evidence of cultural deposits and palynological analysis of lacustrine bed formed in the tributary basin of the Hant'an River indicate that hominid occupation occurred in this basin under rapidly deteriorating climatic conditions. From three thermoluminescence dates, the timing of hominid occupation as represented by 'Acheulian-like' bifaces apparently occur sometime during 45,000 BP. Thus, deposition of cultural layers in this basin approximately coincides with the beginning of the second stadial of the final glacial, during which the Korean Peninsula must have had provided a sanctuary for prolonged human occupation.