• Journal of the Korean earth science society
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• v.24 no.6
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• pp.568-577
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• 2003

The purpose of this paper is to examine the geomorphic processes of beach and sanddune development in the Chungcheong-Namdo Province. The sands consist mainly of quartz and feldspar with lesser amounts of mica 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 low degrees of roundness and grading indicating that source areas for the material were in the vicinity of the accumulating field. Over the years, the beaches have receded as a response to the decreasing amount of depositional materials. The driving force for the formation and transformation of coastal dunes in the study area is dominant winds from the center of the Siberian High. To some extent, the erosion of coastal dunes has been a global phenomenon. The degradation process occurred most actively when spring tides attacked beaches, berms, and foredunes. The relief and shape of present-day coastal dunes is determined initially by the Pleistocene strata underneath. From the fact that the strata contained traces of frozen structure, it can be inferred that sediment once experienced the process of soil formation.

• Economic and Environmental Geology
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• v.19 no.2
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• pp.153-163
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• 1986

Paleomagnetic and geological studies of volcanic and sedimentary rocks of Jeju Island have been carried out to determine the position of virtual geomagnetic pole(VGP), and to estimate the geological sequence and their age. As a result of paleomagnetic studies, the reversal polarities are measured in the Sanbangsan trachyte and Hwasun formation, and the normal are the rest. In case of normal polarity, the mean values of declination and inclination are $2.3^{\circ}$ and $48.4^{\circ}$, respectively, and the average value of VGP is $85.4^{\circ}N$ and $79.9^{\circ}W$. The locations of VGP's are coincident with those obtained from world-wide Plio-Pleistocene rocks. The Hwasun formation and Seongsan formation which have been known to be sedimented in the similar time in the 2nd-stage of volcanic eruption, possess reversal and normal polarities, respectively. This fact brings about the result that two formations should be separated in a sense of geological sequence. Consequently, the geological sequence of the 2nd-stage of volcanic eruption is Pyoseonri basalt-Seoguipo hawaiite-Hwasun formation-Seongsan formation-Jungmun hawaiite-Sanbangsan trachyte. Referring to the paleomagnetic studies and the previous and present geological studies, Seoguipo formation corresponds to the Gauss normal epoch, the 2nd-stage of volcanic eruption to Matuyama reversed epoch, and the 3rd-, 4th-, and 5th-stages to Brunhes normal epoch. Therefore, the Seoguipo formation is mostly sedimented during late Pliocene and/or presumably extended to the early Pleistocene. The rocks of the 2nd- to 5th-stage are formed later than this.

• 한국해양학회지
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• v.20 no.3
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• pp.55-61
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• 1985

Two hundred suspended-matter samples were collected from the continental shelf off the southeast coast of Korea during September, 1981, March, 1982 and April 1983. Superficial bottom sediments on the shelf were also taken. Based on the alalyses of TSM distribution and concentration patterns, it is considered that finegrained suspended matters are restricted to nearshore-inner shelf showing a band or zone paralleling with coastal morphology. This fact suggests a limitation of "modern" fine grained sediments to a nearshore and inner shelf band. The sand deposits with the lower value of mud content (<5%) adjacent to the shelf break and on the outer shelf would probably be "relict" sediments (old beach sediments) deposited in response to a lower stand of sea level during the Pleistocene ice age. The transgression did little to alter the distribution of sand on the outer shelf in this particular study area. The progress of shore line was so rapid that a given locality was in the beach zone and subject to rapid longshore drift and extensive reworking only for a few years. Probably the most pronounced effect of the transgression was sorting of the sand, and at least partial winnowing out of the finer fractions.

• 한국해양학회지
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• v.30 no.3
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• pp.216-226
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• 1995

Stable isotopic and elemental compositions were analyzed for well- preserved calcareous skeletons (gastropods, pectenids, brachiopods, a scaphopod, and other bivalves) of the Pleistocene Seoguipo Formation from Cheju Island, Korea. Mineralogically and texturally, aragonitic and calcitic fossils still retain their original mineralogy and microstructure. High $\delta$$\^$18/O and $\delta$$\^$13/C contents indicate that the shells have not been altered by the post-burial diagenesis. Also, this is supported by high Na and Sr contents as well as low Mn and Fe compositions of the shells. Oxygen isotopic compositions of the well preserved fossils show that the organisms had lived under the lower paleotemperature or within the isotopically enriched paleo-seawater during the deposition of the Seoguipo Formation. This result strongly implies that the Seoguipo Formation was deposited during a glacial period. The paleotemperature variation throughout the sequence during the deposition of the Sewguipo Formation was negligible.

• Journal of Environmental Impact Assessment
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• v.15 no.5
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• pp.323-337
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• 2006

This work discussed the species composition, phylogeny, spatio-temporal distribution, ecology and natural history of North Korean Pinaceae or pine tree family, which seems to be important to maintain nature and ecosystem in the Korean Peninsula. Out of five genera and sixteen species of Pinaceae of the Korean Peninsula, North Korea contains four genera and eleven species of Pinaceae, including Pinus densilflora, P. koraiensis, P. pumila, Picea jezoensis, P. koraiensis, P. koraiensis var. koraiensis, P. pungsanensis, Larix gmelini, L. gmelinii var. olgensis, Abies holophylla and A. nephrolepis. In terms of phylogeny Pinus is closely related to Picea, and followed by Larix. Abies is close to Tsuga which only occur at Ullung Island. Distributional pattern of North Korean Pinaceae can be classified into four types; three species of nation-wide montane type i.e., Pinus densilflora, P. koraiensis and Abies holophylla, four species of central and northern subalpine type, i.e., Pinus pumila, Picea koraiensis, Larix gmelini and Abies nephrolepis, one nation-wide subalpine type, Picea jezoensis, and three species disjunctive to north type, i.e., Picea koraiensis var. koraiensis, P. pungsanensis, and Larix gmelinii var. olgensis. Pinaceae species occurring on the alpine and subalpine belts of North Korea, such as Pinus koraiensis, P. pumila, Picea jezoensis, P. koraiensis, P. koraiensis var. koraiensis, P. pungsanensis, Larix gmelini, L. gmelinii var. olgensis and A. nephrolepis are considered as the glacial descendant from the boreal region. Those species might have migrated from the north during the Pleistocene glacial epochs in search of favourable condition, and since the Holocene period they survived on the hostile alpine and subalpine environments, in which they are more competitive than warmth-tolerant temperate vegetation. Certain species, such as Picea pungsanensis, is segregated on the isolated mountains since the Pleistocene period, and forced to adapt to local environment, and eventually became an endemic species of North Korea. Recent rapid global warming trend especially in northern high mountains of North Korea could cause an unfavourable environment for the survival of cold-tolerant Pinaceae of the alpine and subalpine belts. Pinus densiflora, which is occurring on the montane belt might faced with difficulties due to both the deforestation and the outbreak of insect-borne disease, such as Bursaphelenchus xylophilus.

• Journal of The Geomorphological Association of Korea
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• v.15 no.2
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• pp.1-9
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• 2008

This studied area is divided into the mountains and the valleys. The former is nearly consisted of the badland, the latter is consisted of alluvial plains in the valley, fluvial terrace at the side of the river, alluvial fans between mountains and river terrace. There are many tors, mushroom rocks, sugarloaves, weathering pits, castle coppies, columnar rocks, pinnacles, balanced rocks carved on tuff by means of erosion in the Chiricahua Nat'l Monument. Willcox Playa is alkalic crust where was lake in pleistocene epoch at the time wetter than present. Alkalic crust was made of Ca, Na, K etc. There are sand dunes around here where was lake side in the past. We found many kinds of fossils at the 2,000ft thick horizons of valley alluvium. Pediment and alluvium bordered at the base of Mt. Dragoon wavily. Exfoliation and spalling and sheeting resulted in boulders around here. Tucson is alluvial plain filled in thick 7,0000ft valley. Volcano, fault, erosion, alluvium were and are processing in this area.

• Journal of the Korean Geographical Society
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• v.45 no.5
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• pp.541-552
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• 2010

Geochemical and physical investigations such as ${\delta}^{13}C$ isotope ratio, carbon/nitrogen (C/N) ratio, magnetic susceptibility (MS), and particle size analyses were carried out on the estuarine tidal flat sediments from the west coast of Korea in order to reconstruct the East Asian summer monsoon variability during the late Pleistocene and Holocene Our results indicated that the summer monsoon probably peaked around 7,700-7,800 yr BP and then started to decline about 7,400 yr BP in the Korean peninsular, and that the monsoon was relatively weak between 24,000-24,500 yr BP but relatively strong between 18,500-19,500 yr BP during the Last Glacial Maximum. Our estuarine geochemical data have proven to be valuable as a new proxy for detecting the shifts in monsoon strength. This new evidence will be helpful, especially for Korean paleoenvironmental studies with few proxy data archives.

• Journal of Environmental Impact Assessment
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• v.21 no.3
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• pp.431-443
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• 2012

Wind holes or air holes, from which cool air blows out during the summer, but mild air comes out during the winter, have provided the phytogeographically important refugia for cryophilous or cold-loving boreal flora during the Holocene period. At present, wind holes are serving as a faraway disjunctive habitat for Pleistocene relict glacial floristic elements, and present an invaluable information to reconstruct the natural history. Present work aims to collate the nationwide distribution and relevant DB on the potential wind holes of Korea based upon media and literature sources, along with geographical informations, such as place name, topographic map, environmental geographical information, flora, monitoring data of Korea National Arboretum, and field survey data. Geographical information on sixty nine wind hole sites have compiled and analyzed on the basis of flora and presence of fossilized periglacial landforms, such as talus, block field, and block stream, and sixteen sites have thereafter carefully selected and scrutinized through field surveys. To maintain a sustainability of wind hole ecosystem, including their original landform, micro-meteorological phenomena and plant community therein as a refugia or habitat for relict plant species of Pleistocene glacial period, appropriate restrictions and preservation measures are required.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.04a
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• pp.66-73
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• 2001

Yangsan fault in the southeastern part of Korean peninsula has been locally reactivated along a prexisted fault during the late Pleistocene time. Geomorphological evidence of the reactivation is revealed at the northern segment(Yugye-ri, Tosung-ri areas) of the Yangsan fault. The reactivation is distinctively characterized by fault gouge and fracture zone with high frequency in the Yugye-ri area. Obique slip separation of the area is about three meters of the middle terrace. The cumulative vertical displacement is recognized after the formation of the middle terrace. Age of the reactivated faulting is constrained to during the formation of dissected valley deposits. Average vertical slip based on paleo-event is inferred to about 0.5-0.7 meter in this area.

• 한국해양학회지
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• v.1
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• pp.16-24
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• 1971

Over 40 bottom sediment samples were collected from the southern sea of Korea. The detailed textural characteristic of the sediments, percent calcium carbonate and heavy and light mineralogy were determined. Seaward of these sediments is a nearly broad belt of sandy sediments. In a broad outline it is considered to constitute a near-shore deposits left from a Pleistocene time of eustatically lowered level of sea water, because the sediments on the outer half of the continental shelf are much coarser than that nearer shore. The carbonate content increases strongly to the southeast and northwest of Cheju Island. It is believed that the high calcium carbonate content can be largely attributed to the availability of carbonate materials.