• Title/Summary/Keyword: 빙기의 기후환경

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Pollen analysis from Osong Archaeological Site, Chungbuk Province: Vegetation and Environmental Implication (충북 청주시 오송지구 유적 발굴지의 화분분석: 색생과 퇴적환경 고찰)

  • Yi, Sang-Heon;Kim, Ju-Yong
    • The Korean Journal of Quaternary Research
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    • v.24 no.1
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    • pp.25-33
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    • 2010
  • Holocene vegetation and climate changes were assumed on the basis of pollen records from Wonpyeong Trench II-3 of the Osong archaeological site, Cheongju, Chungbuk Province, Korea. An organic matter beared in coarse sediments appeared to be low throughout the succession. Although an occurrence of pollen grains is not high, some dominant and principal taxa may indicate vegetation changes response to climate changes in central inland area of the Korean Peninsula. The age determination can be estimated with indirect way by comparing with previous age-controlled pollen studies. It is assumed that the former last glacial conifer forests had been changed into open mixed conifers and deciduous broadleaved forest during the early Holocene period. Warmer and more humid climate conditions, during the mid-Holocene, might have allowed the hardwoods including deciduous- and evergreen-broadleaved trees, and warm-preferring pine tree to flourish. Subsequently, the former forests were replaced by mixed of conifer and deciduous broadleaved forest owing to deterioration of climate conditions during the late Holocene. Human activity is also detected by agricultural indicators, such as buckwheat and large pollen grains comparable to corn, in upper most pollen profile. During this time, the forests in studied area were primarily affected by human disturbance rather than natural environment.

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The Process of Hillslope Denudation Since the Last Glacial Maximum Near Tangjeong-myeon, Asan-si, Central Korea (아산시(牙山市) 탕정면(湯井面) 일대(一帶) 최종빙기(最終氷期) 최성기(最盛期) 이후(以後) 구사면(丘斜面)의 삭박과정(削剝過程))

  • PARK, Ji-Hoon;JANG, Dong-Ho
    • Journal of The Geomorphological Association of Korea
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    • v.15 no.2
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    • pp.67-83
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    • 2008
  • To find out the process of hillslope denudation since the Last Glacial Maximum in Asan area, we conducted the stratiform interpretation and carbon age measurements with the collected samples through trenching in the valley bottom of 'Agol' located in the lower stream of Magok stream. The results are as follows. 11 inorganic and 8 organic matter layers were confirmed at the point of trench MG1 in the subject area, 7 inorganic and 3 organic at the point of trench MG2, and 5 inorganic and 3 organic at the point of trench MG3, respectively. The frequency of hillslope denudation, hillslope mass movement, which had occurred in the unstable environment of back hillslope at the point of MG 1, was 11 times (8 times before about 2,900yrBP, twice in between about 2,900~1,900yrBP, and once after about 1,900yrBP) as a whole. The frequency of moor which had formed in the comparatively stable environment of back hillslope was 9 times (5 times before about 3,000yrBP, twice in between 3,000~2,800yrBP, and once in between 2,200~1,900yrBP) at minimum. The frequency of back hillslope denudation at the point of MG2 was totally 7 times (4 times before about 1,900yrBP and 3 times after about 1,900yrBP) and the moor formations were 3 times (twice before about 1,900yrBP and once after 1,900yrBP). The frequency of back hillslope denudation at the point of MG3 was totally 5 times (3 times before about 1,900yrBP and twice after about 1,900yrBP) and the moor formations were 3 times (twice before about 1,900yrBP and once after 1,900yrBP). The hillslope surrounded by valley bottom of 'Agol' was confirmed as the pile up of various inorganic matters by the mass movement such as sand or sandy gravel in the valley bottom of the subject area, formed not once but several times of denudation. We could know that the hillslope denudation cycle converged to the time period of $10^2{\sim}10^3$ years. These results will be an important basic data for restoring hillslope denudation process near Asan and changing climate of the Late Quaternary Period.

Formation Process of the Second Mujechi Moor (무제치 제2늪의 형성과정)

  • Son, Myoung-Won
    • Journal of the Korean association of regional geographers
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    • v.10 no.1
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    • pp.206-214
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    • 2004
  • The purpose of this paper is to elucidate the formation process of the Second Mujechi Moor at Mt. Jeongjok. For doing so, 1 analysed the formation process of valley which moor is located in, and the formation process of block field damming the valley: First, it is not a valley but a hollow which the Second Mujechi Moor located in. Hollow was formed as weathering bedrock weathered deeply along joints under warm and wet climatic conditions was denudated by rain wash. Second, the Second Mujechi Moor had been a marginal lake. Block stream developed during the last glacial period of Pleistocene, and it dammed the mouth of hollow. Afterwards sediments transported from slope filled the marginal lake, thus the lake changed to the moor where aquatic plants could grown. Third, the Second Mujechi Moor is drained and dried out by removal of matrix material from the block stream dam of the mouth of moor. For keeping moor's present conditions, we must control moor's drainage by filling open space in block stream with fine material.

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Concepts and Geomorphic Properties on Fluvial Terraces (하안단구의 개념과 지형 특성)

  • Lee, Gwang-Ryul
    • The Korean Journal of Quaternary Research
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    • v.25 no.1
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    • pp.1-13
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    • 2011
  • To reinterpret the meaning of fluvial terraces in the Quaternary researches, the concepts and geomorphic properties of fluvial terraces are reviewed. Fluvial terraces are the alluvial landform that was once river channel or floodplain by paleochannel flowed in elevated areas from the current river by active incision of rivers due to the climatic changes and/or uplifts. As fluvial terraces are the remnants of alluviums after incisions of rivers, the major factors influencing on the incisions are the falling of erosion base, increase of river discharge and distinct geomorphic phenomenon of river. While it is generally known that fluvial terraces deposits in the upper or middle reaches of large rivers were formed during glacial periods, the deposits may be formed at the various periods due to the diverse natural environments and geomorphic properties of specific rivers, because there have been numerous cases that the ages of fluvial terraces in the upper or middle reaches of large rivers in Korea and China can be correlated to the interglacial periods.

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Quaternary Sea Levels Estimated from River Terraces of the Ungcheon River, Midwestern Coast of South Korea (態川川流域의 河成段丘로부터 推定되는 舊汀線高度와 그 意義, 韓國 西海岸의 第四紀 環境變化 究明에 있어서 臨海山岳地域 小河川 河成段丘 硏究의 重要性 考察)

  • Choi, Seong-Gil
    • 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.

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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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Geomorphic Features of ${\check{O}}rumkol$(Frozen Valley) Area (Kyungnam Province, South Korea) - Mainly about Talus - (경남 밀양 얼음골 일대의 지형적 특성 -Talus를 중심으로-)

  • Jeon, Young-Gweon
    • Journal of the Korean association of regional geographers
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    • v.3 no.1
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    • pp.165-182
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    • 1997
  • The aim of this paper is to clarify geomorphic features on talus within ${\check{O}}rumkol$ and the origin of ${\check{O}}rumkol$. ${\check{O}}rumkol$ is located in Milyang of Kyungnam province, in South Korea. ${\check{O}}rumkol$ is good area to study talus. because it is characterized by following three geomorphic landscapes : free face surrounding ${\check{O}}rumkol$ ; ${\check{O}}rumkol$ with deep and wide valley floor ; lots of taluses typically developing within ${\check{O}}rumkol$. The main results can be summarized as follows: 1) The origin of ${\check{O}}rumkol$ may be suggested two assumptions : one is that its origin have been resulted from intrusion structure(intrusive rock might capture less resistant rock as tuff) ; the other is that its origin have been resulted from volcanic depression after intrusion or eruption. But these assumptions are not obvious. therefore more geological evidences will be supplemented after this 2) The characteristics of ${\check{O}}rumkol$ talus (1) Pattern ${\check{O}}rumkol$ taluses are tongue-shaped or cone-shaped in appearance. They are $50{\sim}200m$ in length and the range of the maximum width from 25 to 115m and one of their mean slope gradient from 32 to $36^{\circ}$ (2) Origin ${\check{O}}rumkol$ taluses have been formed under periglacial environment in the last glacial age and they are classified into rock fall talus type, considering in conjunction with the shape, hardness, sorting, weathering conditions of constituent debris. (3) The stage of landform development ${\check{O}}rumkol$ talus slope profiles are mainly concave slope. This concave slope type was eventually caused by talus creep at the lower end of the talus. That means new additions of debris from the free face have virtually ceased and there is no evidence of recent motion in the deposit. Now it is predominant that vegetation cover is gradually increasingly. Therefore ${\check{O}}rumkol$ taluses appear to be relict form stage. at present.

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The Plant Species Composition and Phytogeographical Significance on Algific Talus Slope in Korea (한반도 풍혈지의 종조성과 식물지리학적 중요성)

  • Kim, Jin-Seok;Chung, Jae-Min;Lee, Byeng-Cheon;Pak, Jae-Hong
    • Korean Journal of Plant Taxonomy
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    • v.36 no.1
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    • pp.61-89
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    • 2006
  • Algific talus slopes are local cold micro-environmental habitats where cool air escapes through vents and fissures of talus layer, and ice forms in summer. To access the phytogeographical significance and to develop the conservation strategy on vegetation of the algific talus, plant species composition on seven algific talus in South Korea was investigated. As a results, phytogeographically significant northern elements such as Cystopteris fragilis (L.) Bernh., Diplazium sibiricum (Turcz. ex Kunze) Sa.Kurata, Polypodium virginianum L., Vaccinium vitis-idaea L. and Hackelia deflexa (Wahlenb.) Opiz were distributed in these algific talus slopes (below $N37^{\circ}43^{\prime}$). In addition, subalpine species such as Woodsia subcordata Turcz, Rosa suavis willd., Clematis fusca var. coreana ($H.L{\acute{e}}v.$ & Vaniot) Nakai, Calamagrostis langsdorfii (Link) Trin. and Carex vaginata var. petersii (C.A.Mey.) Akiyama were also distributed as typical relictual species of these algific talus (less than alt. 400m). The algific talus slopes in Korean peninsular can be regarded as the insular refugia that northern plant species advanced southward during the latest glacial age have been isolated and adapted in some local microhabitats. Because the algific talus slopes as paleorefugia are very important in terms of phytogeography as well as meteorology ans geology, developments of strategies for in situ and ex situ conservation on these small isolated and threatened populations associated with the algific talus urgently needed.