• Title/Summary/Keyword: periglacial

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Environmental Characteristics of Wind-Hole and Phytogeographical Values (풍혈의 환경 특성과 식물지리적 가치)

  • Kong, Woo-Seok;Lee, Slegee;Yoon, Kwanghee;Park, Heena
    • Journal of Environmental Impact Assessment
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    • v.20 no.3
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    • pp.381-395
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    • 2011
  • Present work aims to establish an integrated management system of environmental data base for nine typical wind holes or air holes in Korea. It basically deals with definition, geographical distribution, morphological pattern, physical characteristics and anthropogenic environments of wind hole to propose systematic preservation strategy of their periglacial landscape and flora, which are known to be sensitive to global warming. Wind hole, in which cool air blows out during the summer, but mild air comes out during the winter from a cave or hole, is frequently found on northwest- and north-facing slopes on the terminal point of steep talus, block field, and block stream, and can be categorized into three types, i.e., talus, cave and sink types. Environmental characteristics of nine wind holes are analyzed on the basis of their geology, landform, climate, soil, hydrology, vegetation, road, footpath, land-use, and management system, and relevant DB are prepared. Wind hole areas with unique landscape and ecological values need to be designated as a nature reserve, and zoning of core, buffer, and transitional zones are required for the multi-dimensional preservation of periglacial landscape and ecosystem. Phytogeographical values of glacial relict plants, including mountain cranberry(Vaccinium vitis-idaea) at its global southernmost limit at Bangnaeri wind hole, Hongchon County, Gangwon Province of Korea are discussed in detail as a floristic refugia in connection with climate change during the Pleistocene Epoch and potential in-situ and ex-situ preservation sites in the future.

The Morpho-Climatic Characteristics of Stratified Slope Deposits in the Southwest Region of Haenam (해남 남서부지역의 Stratified Slope Deposit의 기후지형학적 특성)

  • PARK, Chul-Woong
    • Journal of The Geomorphological Association of Korea
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    • v.15 no.2
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    • pp.11-24
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    • 2008
  • Stratified slope was formed on the SSE-facing slope in the southwest region of Haenam, South Korea. Field and laboratory investigations into the geomorphology and sedimentology of stratified slope deposit that is inactive. Outcrops of this deposit show an alteration of coarse debris-supported matrix and tiny debris-supported matrix layers. Sedimentological analysis(particle-size analysis) indicates that this deposit is not fluvial process or only gravitation like rock-fall. Many clasts and fine materials on the slope is supposed to be product by congelifraction under Pleistocene periglacial climatic environment. Also The processes responsible for the genesis of this deposit probably are to move downward by gelifluction and to remove fine materials by slope wash in thawing cycle and in situ debris congelifraction on gelifluction slope. Now It is impossible to account for the time range of genesis(diurnal, seasonal). In conclusion, this stratified slope formed in cold and humid periglacial environmental in pleistocene, therefore, this slope is a periglacial relic landform, indicates that in south korea there was a cold and humid paleo-climate such as periglacial environmen.

Type and Characteristics of Debris Landform in Mt. Mudeung (무등산 암설지형의 유형과 특징)

  • Oh, Jong-Joo;Park, Seoung-Phill;Seong, Yeong-Bae
    • Journal of the Korean association of regional geographers
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    • v.18 no.3
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    • pp.253-267
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    • 2012
  • The study looked into the type and characteristics of debris landforms in Mt. Mudeung. By focusing on the representative area, we aimed to categorize the debris landforms based on the morphologic and genetic characteristcis. The types of debris areas in Mt. Mudeung can be divided into the exposed debris type, mixed type of matrix, and the boulder-hidden type. Supply of block in the debris slope area displays different features depending on types of rocks. For the stony slopes of andesite, the block must be moved from the columnar joint or cliff in the upper part. The andesite debris slopes display dominant edge shape while displaying no round shape. The granite stony slopes display dominant round shape and the present exposed slope was assumed to be formed as the core stone which was deep weathered moved along slope during the periglacial era and the matrix was removed after post-glacial era. The movements of blocks are assumed to be caused by solifluction process. The joint area where granite and andesite areas meet, granite is located beneath andesite area, and this implies that blocks were actively freezing and creeping by solifluction and freezing and thawing at that time. It can be assumes that the granite matrix formed plain slope and then andesite boulder covered up the slope. Currently, the blocks in the stony slopes of Mt. Mudeung shows almost no mobility and the stony slopes created under periglacial climate can be considered to be fossil landform.

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The Characteristics and Frost Creep of Granite Regoliths (화강암 풍화층의 특성과 결빙포행)

  • Kwon, Soon-Shik
    • Journal of the Korean association of regional geographers
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    • v.9 no.4
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    • pp.534-545
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    • 2003
  • The main purpose of this paper is to describe the granitic regolith and frost creep phenomena in Daegwanryung area in order to demonstrate the relationship of the weathered materials and the surrounding surface, in order to point out that the characteristics of this particular complex of granitic regolith most closely resemble those of soil frost creep phenomena formed elsewhere under periglacial conditions. For this study, the writer has clarified their structure and its associated milieux, with a group of methods and techniques, field survey, micro-morphological analysis, granulometry of weathered materials etc. Such facies of granitic regolith in situ with silty heterometric materials and micas are prone to be deformed by cryo-suction as well as deep freezing. It was probably formed by cryogenic activity, or frost creep in the periglacial climate of a very cold and humid condition.

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Variationsin Air and Ground Temperatures During a Frozen Season in the Subalpine Zone of Mt. Halla (한라산 아고산대의 동결기 기온 및 지온변화)

  • Kim, Taeho
    • Journal of The Geomorphological Association of Korea
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    • v.20 no.3
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    • pp.95-107
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    • 2013
  • In order to examine the temperature regime responsible for periglacial processes, air and ground temperatures were monitored from October 2010 to May 2011 at a subalpine bare patch (1,710m asl) of Mt. Halla. Four thermistor sensor probes were installed at 55 cm above a ground surface and depths of 2 cm, 10 cm, and 20 cm, respectively. A mean air temperature is $-0.1^{\circ}C$, while mean ground temperatures are $1.8^{\circ}C$ at 2 cm, $2.6^{\circ}C$ at 10 cm and $3.2^{\circ}C$ at 20 cm deep. A mean monthly ground temperature at 2 cm deep demonstrates below $0^{\circ}C$ successively from January to March, while those at 10 cm and 20 cm deep show no sub-zero temperature. A total of 72 freeze-thaw cycle was observed in air temperature. However, the numbers in ground temperature reduced into 17 at 2 cm, 8 at 10 cm, and 3 at 20 cm deep. The cycles of air temperature and ground temperature at 2 cm deep mostly fluctuated diurnally, while those of ground temperature at 10 cm and 20 cm deep exhibited a several-daily oscillation. Snow cover over 55 cm high remained from January to early April, and it seemed to disappear completely on April 16. A seasonal frost of at least 2 cm thick was formed on late December and the isotherm of $0^{\circ}C$ descended slowly into 10 cm deep on late March to early April due to the insulating snow cover. It showed the maximum freezing depth of 20 cm on April 7 to 14 and then thawed rapidly so that the frozen ground did not longer after April 17. Periglacial processes are predominant during a freezing period than a thawing period when the ground surface is still covered with snow. The periglacial mass movement in the subalpine zone of Mt. Halla is mainly generated by frost creep in terms of the occurrence depth of diurnal freeze-thaw cycle and the maximum freezing depth of ground.

Morphogenetic Environment of Jilmoe Bog in the Odae Mountain National Park (오대산국립공원 내 "질뫼늪"의 지형생성환경)

  • Son, Myoung-Won;Park, Kyeong
    • Journal of the Korean association of regional geographers
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    • v.5 no.2
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    • pp.133-142
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    • 1999
  • The wetland is very important ecologically as a habitat of diverse organisms. The purpose of this paper is to elucidate the morphogenetic environment of Jilmoe Bog found in the Odae Mountain National Park Jilmoe Bog is located in the high etchplain(1,060m) where Daebo Granite which had intruded in Jura epoch of Mesozoic era has weathered deeply and has uplifted in the Tertiary. The annual mean temperature of study area is $5.3^{\circ}C$, the annual precipitation is 2,888mm. The minimun temperature of the coldest month(january) is below $-30^{\circ}C$ and the depth of frozen soil is over 1.6m. Jilmoe bog consists of a large bog and a small bog. The length of the large bog is 63m and its width is 42m. The basal surface of Jilmoe bog is uneven. Jilmoe bog is a string bog fanned due to frost actions. In String bog, its surface is wavy with stepped dry hills and net-like troughs crossing hill slope. It seems that string bog is related to the permofrost or seasonal permofrost of cold conifer forest(taiga) zone(where the depth of frozen soil is very deep in the least in winters). String bog is a kind of thermokarst that frozen soil thaws differentially locally in declining permofrost and ground surface becomes irregular. There is turf-banked terracette of width $30{\sim}40cm$ in the headwall of small cirque-type nivation hollow formed at footslope of Maebong mountain around Jilmoe bog. This turf-banked terracette is formed by the frost growth of soil water below grass mat in periglacial climate environment. Where water is plentiful such as a nivation follow${\sim}$valley corridor and a headwall of valley, turf patterned grounds of width $30{\sim}50cm$ are found. This turf patterned ground is 'unclassified patterned ground', earth hummock. In conclusion, Jilmoe bog is a string bog of thermokarst that the relief of ground surface is irregular according to locally differentially thawing of permofrost(frozen soil). Jilmoe bog is high moor, its surroundings belongs to periglacial environment that turf-banked terracette and turf patterned ground are fanned actively.

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Earth Hummocks on the Crater Floor of Baegnokdam at Mt. Halla (한라산 백록담 화구저의 유상구조토)

  • 김태호
    • 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.

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The Formation and Geomorphic Development of Chon-hwang-san(Mt.) Talus (천황산 Talus의 형성과 지형발달)

  • Jeon, Young-Gweon
    • Journal of the Korean association of regional geographers
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    • v.2 no.2
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    • pp.173-182
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    • 1996
  • The intent of this paper is to examine the talus in Chon-hwang-san in the southern part of Korean Peninsula, and then analyze its geomorphic feature and origin. The research is summarized as follows; (1) The talus is 220m long and the range of the width from 10 to 75m. The mean gradient is $33^{\circ}$ and the mean block size is $110{\times}59cm$(long axis$\times$short axis). The overall appearance of the talus is tongue-shaped and the geology of the constituent blocks is dacite. (2) This talus has two particular geomorphic landscapes. One is that the talus has not free face as source of blocks back of itself; the free face of the talus has been parallel retreated to disappearance by frost attack. The other is that the upper part of the talus is on the ridge. (3) This talus is classified into rock fall talus type, and the shape of rock fragments is angular. When considered in conjunction with face of being mentioned above, the morphology and lithology of the talus are best explained on the basis of origin under periglacial environment during late pleistocene time. (4) Most constituent rock debris are now lichen-covered, or covered with a mantle of weathering. There is no evidence of appreciable movement and for supplying block. Therefore, the talus appears to be relict or fossil form stage, currently.

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A Study on the Boulder Stream of Granitoid in Korea (한국 화강암질암류 산지에서 발달하는 암괴류에 관한 연구)

  • Jeon, Young-Gweon
    • Journal of the Korean association of regional geographers
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    • v.6 no.2
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    • pp.71-82
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    • 2000
  • The purpose of this paper is to clarify geomorphic features and development on the boulder stream of granitoid in Korea. Considering the purpose and the method of this paper, three boulder streams are selected : Biseulsan(Mt. Biseul) boulder stream (Daegu city), Maneosan (Mt. Maneo) boulder stream(Gyeongnam province), Geumjeongsan(Mt. Geumjeong) boulder stream (Busan city). The boulder streams mentioned above are bigger in scale and more typical in shape than any other ones in the Korean Peninsula. The main results are summarized as follows. 1. The following are the main features of the boulder streams morphology : the mean gradient is $3{\sim}25^{\circ}$, the longer axes of the component boulders within the deposits averaged about 2m in length, the shapes of the component boulders may be both subangular and subrounded features. 2. The formation of the component boulders is associated with deep weathering of granitoid under warm humid conditions, and the downward movement of boulders occurred by solifluction and frost creep under periglacial conditions. 3. The geomorphic development stage of the boulder streams may be classified into four stages. These boulder streams come under fossil landform stage, the 4th stage ; evidence provided by lichens and weathering features indicate inactive or fossil landform. 4. In generally, boulder streams are well developed on shallow valley floors.

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