• Journal of the Korean earth science society
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• v.29 no.4
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• pp.319-327
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• 2008

A paleobotanical study of the Metasequoia has been carried out from the Miocene Keumkwangdong Formation of the non-marine Janggi Group in the Pohang Basin. As a result of this study, deciduous leafy shoots mostly belong to a single species of Metasequoia occidentalis. This species is characterized by its opposite leaves with decurrent base, and by its presence of scale leaf at base of petiole. This species is common in the Korean Tertiary floras in Miocene age, yet it has not been recorded in the Korean Peninsula after Miocene. Based on the distribution and ecology of extant Metasequoia. it is considered that the Metasequoia might have flourished in the fluvial plains as swamp forest.

• Korean Journal of Mineralogy and Petrology
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• v.35 no.1
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• pp.51-64
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• 2022

For effective preservation of the rocks, which bearing plant fossils at Gumkwangdong Formation, Pohang, the properties of rock and treatment of chemicals were examined in an artificial weathering test. The rocks are diatomaceous siliceous mudstone, which contain a small amount of smectite and has developed laminated layers. The rocks react with water, the d₀₀₁ spacing of smectite was increased. On the one hand, the physical properties of the rock samples, such as surface hardness, improved after the application of ethyl silicate-based stone strengthener. On the other hand, the spacing of interlayer of swelling clay minerals decreased and spacing of laminae layer increased. When the ethyl silicate-based stone strengthener was applied after pretreatment with a swelling inhibitor, interlayer and spacing of laminae changes were similar to those when only the stone strengthener was treated. The effect of the swelling inhibitor was almost negligible. When the rocks that have been conserved with chemicals react with water, spacing of laminae has widened much, whereas when the rocks was in contact with moisture only, there was little change. In addition, if it is placed in the outdoor after conservation treatment, although it occurs slightly slower than the untreated rock, the separation of the lamination layer and the pulverization of the rock occur within a very short time. Consolidation is required to improve the physical properties of fossil rock, but when exposed to rain and undergoing freeze-thaw process, the effect is lost very quickly. Therefore, regardless of the chemical treatment, it is a priority to prevent direct rainfall contact with the rock.