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Volume 54 (2015)
- Issue 6 Pages 345-
- Issue 5 Pages 205-
- Issue 4 Pages 149-
- Issue 3 Pages 101-
- Issue 2 Pages 53-
- Issue 1 Pages 1-
Volume 54, Issue 4
Displaying 1-3 of 3 articles from this issue
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Articles
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Hiroshi Moriwaki, Yoshiaki Matsushima, Shigeo Sugihara, Akio Ohira, Ki ...2015 Volume 54 Issue 4 Pages 149-171
Published: August 01, 2015
Released on J-STAGE: September 25, 2015
JOURNAL FREE ACCESSKokubu plain is suitable for obtaining the records of sea levels and palaeoenvironments since the last deglaciation, because thick coastal deposits since this stage occur in the region. We examined changes in sea level and palaeoenvi-ronments over the past 15,000 years on the basis of palaeoenvironmental records of sedimentary facies, shells, foraminifers and diatoms, and chronological data of tephras and 14C dates in three cores obtained on Kokobu plain.
The results are as follows. Kagoshima Bay was a lake with a level c. 90m below the present sea level in the Last Glacial Maximum. Sea level was 85〜90m below the present sea level and the sea attained the head of the bay at c. 14,500 calBP. Subsequent rapid sea-level rise occurred in two stages at c. 14,500〜13,000calBP and 11,500〜7,500calBP. A shallow sea or tidal flat was maintained in the present coastal area even during the course of rapid sea-level rise in the last deglaciation. The head of the bay was not closed by the growth of Sakurajima volcano at the southern rim of Aira caldera. These changes in sea level and palaeoenvironments are precisely correlated with marine oxygen isotope records using Sakurajima Satsuma tephra (ca. 12,800 calBP).View full abstractDownload PDF (2951K) -
Yoshitaka Denda2015 Volume 54 Issue 4 Pages 173-183
Published: August 01, 2015
Released on J-STAGE: September 25, 2015
JOURNAL FREE ACCESSThis paper examines the formation process of a spatial distribution pattern of the Upper Palaeolithic assemblage dated to ca. 21,000calyr BP obtained from an area excavated in 2011 at the Takaseyama site in Yamagata Prefecture. The lithic assemblage examined in this paper is likely to have been deposited between the flood loam layers formed by repeated floods of the Mogami River in the Late Pleistocene. In order to examine a hypothesis that the lithic distribu-tion pattern we can observe today was the one modified by the action of the water flow on the ground surface, this study discusses what kinds of and to what extent the disturbance factors for the original lithic distribution were affected using a fabric analysis, a size sorting analysis, and a microscopic analysis of surface alteration features of the lithic artifacts. The results indicated that there are different trends between the lithic artifacts and the pebbles yielded from the same loam layer. The fabric analysis made clear that the pebbles may have been strongly influenced by the runoff and bioturbation pro-cesses. Although relatively small lithic artifacts (2-4mm) were apparently removed from the original positions by the water flow, the artifacts over 14mm long were not removed from the positions where they had been originally dis-carded or abandoned. It is highly likely that the spatial distribution pattern of the lithic artifacts over 14mm in the site has retained the in-situ condition that reflected the activity of the Upper Palaeolithic people.View full abstractDownload PDF (1560K) -
Rika Nishiuchi, Arata Momohara, Kunihiko Endo, Shigeto Osato, Susumu O ...2015 Volume 54 Issue 4 Pages 185-201
Published: August 01, 2015
Released on J-STAGE: September 25, 2015
JOURNAL FREE ACCESSPaleovegetation during the latest stage of the last glacial maximum (LGM ; 20,300-16,600cal BP) was reconstructed based on pollen and plant macrofossil assemblages from a deposit on a hill in a small valley with a very limited upstream watershed in Nakazato, Utsunomiya City, central Japan. The macrofossil assemblages represented local vegetation on the valley slope and were composed mainly of trees dominant in modern subalpine forests, such as Picea jezoensis var. hondoensis, Tsuga diversifolia, Abies veitchii, and Betula ermanii. The coniferous forest included cool temperate deciduous broad-leaved trees such as Acer amoenum, A. mono, and Prunus, and the forest floor was covered by bryophytes and ferns. After 18,800calBP, pinaceous conifer pollen decreased and Betula, Carpinus-Ostrya, Ulmus-Zelkova, Acer, and Tilia pollen increased, indicating an increase in deciduous broad-leaved trees in lower altitude areas with warming of the climate following the LGM termination (〜19,000calBP). Based on comparison with other plant macrofossil assemblages reported from various altitudes in central Japan representative of the LGM, the plant macrofossil assemblages in Nakazato dominated by modern subalpine forest elements are assumed to represent the species composition of forests on the slopes of hills and mountains during the LGM. On the other hand, Picea sect. Picea, Larix, and Pinus koraiensis representative of plant macrofossil assemblages during LGM in central Japan comprised mixed coniferous and deciduous broad-leaved forest distributed mainly in and around wetlands in the floodplains of rivers in lowland areas.View full abstractDownload PDF (1831K)
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