第四紀研究
Online ISSN : 1881-8129
Print ISSN : 0418-2642
ISSN-L : 0418-2642
29 巻 , 4 号
選択された号の論文の8件中1~8を表示しています
  • 河村 善也, 松橋 義隆, 松浦 秀治
    1990 年 29 巻 4 号 p. 307-317
    発行日: 1990/10/20
    公開日: 2009/08/21
    ジャーナル フリー
    This paper offers detailed descriptions of the late Quaternary fossil-bearing sediments of Suse Quarry and their mammalian faunas, with a discussion on the faunal succession between the latest Pleistocene and early Holocene in the Pacific coastal region of central Japan.
    The sediments of the quarry were found in two fissures (East and West Fissures) exposed on the limestone quarry faces in 1975. Those of East Fissure are composed of brown to yellowish brown mud, and the 14C age of fossil bones from them is determined to be 14, 710±670y. B. P. The sediments of West Fissureconsist of brown mud with breccia, and the fluorine analysis of fossil bones suggests that the sediments are younger than those of East Fissure, and are possibly assigned to the last part of the Late Pleistocene to the early Holocene in age.
    With the exception of an extinct deer species, Cervus praenipponicus, the assemblage of East Fissure (Table 2) is composed of extant forms which are found in present-day Honshu. It is also characterized by the absence of wild boar, in contrast to the abundant occurrence of deer remains. The assemblage of West Fissure (Table 3), on the other hand, includes neither extinct forms nor extant forms which are now absent from Honshu. Additionally, remains of wild boar ate commonly found in association with deer remains.
    On the basis of the data from these two assemblages and those from Site 5 of Yage Quarry (14C age: 18, 040±990y. B. P.) and other Late Pleistocene and Holocene fossil localities in the region, we can postulate the following faunal succession:
    About 18, 000 years ago, the fauna were generally similar to those of lowlands and low mountains of present-day Honshu, but also contained extinct forms (Anourosorex japonicus, Microtus cf. brandtioides and Cervus praenipponicus) and a form exotic to present-day Honshu (Ursus cf. arctos). In spite of the abundant occurrence of deer, wild boar was almost absent in the fauna. The above-mentioned extinct and exotic forms (except for C. praenipponicus) vanished between 18, 000y. B. P. and 15, 000y. B. P. The fauna of 15, 000y. B. P. became more similar to the present one, but wild boar were almost absent as in 18, 000y. B. P. From 15, 000y. B. P. to the early Holocene, the number of wild boar increased drastically, and then the fauna became almost identical with that of present-day Honshu.
  • 柳井 清治, 五十嵐 八枝子
    1990 年 29 巻 4 号 p. 319-336
    発行日: 1990/10/20
    公開日: 2009/08/21
    ジャーナル フリー
    The temporal frequency of slope failures in the terraces of Hidaka district, Central Hokkaido, and the environment inducing them were studied by tephrochronology, pollen analysis, and radio carbon dating. The morphology of the slope failures caused by torrential rains in 1981 in the area can be classified into two types: (1) deep circular gullies on gentle sloping terraces, and (2) soil slips from the surface layer in the steep slopes of dissected valleys.
    Most of the failure material in gullies (1) was formed as a result of the increasing rainfall during the Allerød Interstadial and early Post Glacial period. This indicates that no gully failure (1) has occurred at least for 8, 000 years. Ancient failure deposits accumulated on the floor of dissected valleys show that slope failures (2) may have occurred on an average of every 150 to 200 years during the last 2, 600 years. The occurrence of slope failure has increased especially during the last 300 years. According to pollen evidence, the climate became cool/wet about 2, 600 years ago, and this has continued almost to the present. Climatic changes are probably related to the initiation of slope failures. The recent increase in slope failures is presumably related to the accumulation of loose volcanic ash and to changes in land-use patterns.
  • 藤田 和夫
    1990 年 29 巻 4 号 p. 337-349
    発行日: 1990/10/20
    公開日: 2009/08/21
    ジャーナル フリー
    The central part of the Kinki area, Southwest Japan, is characterized by the alternative arrangement of basin and range, which is the topographic expression of the differential movements of the faulted blocks of the basement rocks. These tectonic movements named the “Rokko Movements”, started in the Middle Pleistocene, as evidenced by the “Manchidani Unconformity” which is recognized between the Middle and Upper Subgroups of the Quaternary Osaka Group.
    The Upper Subgroup not only was deposited in the tectonic basins formed by the Rokko Movements, but also spread over intermontane basins in the wide background mountain areas overlapping various horizons of the Middle and Lower Subgroups. Such an unconformable relationship is considered to show that the large-scale sea-level rise occurred almost contemporaneously with the tectonic movements.
  • 清永 丈太
    1990 年 29 巻 4 号 p. 351-360
    発行日: 1990/10/20
    公開日: 2009/08/21
    ジャーナル フリー
    Pollen analysis of a 5, 500 year-core of peaty sediment from an alluvial lowland of the River Kashio, in the southwestern part of Yokohama, Central Japan, showed the following vegetational changes over this area.
    (1) At ca. 5, 500y. B. P. such deciduous trees as Quercus subgen. Lepidobalanus, Celtis-Aphananthe and Carpinus-Ostrya abundantly existed along with much Quercus subgen. Cyclobalanopsis and scanty Pasania-Castanopsis, both of which are the main elements of laurel forests. Cyclobalanopsis slightly increased twards ca. 4, 700y. B. P., while many taxa of deciduous broad-leaved trees declined ca. 4, 700y. B. P. But Lepidobalanus remained the main element of forest vegetation till ca. 2, 800y. B. P.
    (2) Pasania-Castanopsis was one of the main elements of forest vegetation between ca. 3, 800y. B. P. and ca. 3, 300y. B. P.
    (3) Pasania-Castanopsis suddenly decreased ca. 3, 300y. B. P., and Cyclobalanopsis did not increase from ca. 4, 700y. B. P. to ca. 2, 800y. B. P. These trends meant that Lepidobalanus increased ca. 3, 300y. B. P.
    (4) Cyclobalanopsis was abundant between ca. 2, 800y. B. P. and ca. 1, 000y. B. P., while Lepidobalanus was not abundant during that period.
    (5) A gradual increase in the amount of Cryptomeria began ca. 4, 700y. B. P., and Cryptomeria was abundant between ca. 2, 600y. B. P. and ca. 1, 000y. B. P.
    (6) Castanea was one of the main elements of forest vegetation from ca. 4, 700y. B. P. to ca. 3, 300y. B. P.
    (7) At ca. 2, 100y. B. P. Gramineae suddenly increased along with the continuous presence of weeds. Pinus suddenly increaed at ca. 1, 000y. B. P., and has been abundant since that time onward. This evidence suggests that human impact on vegetation has been intensified since ca. 2, 100y. B. P., and especially since ca. 1, 000y. B. P.
  • 吉田 史郎, 竹内 圭史, 吉川 清志
    1990 年 29 巻 4 号 p. 361-369
    発行日: 1990/10/20
    公開日: 2009/08/21
    ジャーナル フリー
  • 小杉 正人, 谷口 英嗣, 日本大学古生態ゼミナール
    1990 年 29 巻 4 号 p. 371-375
    発行日: 1990/10/20
    公開日: 2009/08/21
    ジャーナル フリー
  • 渡辺 直経
    1990 年 29 巻 4 号 p. 377-380
    発行日: 1990/10/20
    公開日: 2009/08/21
    ジャーナル フリー
  • 1990 年 29 巻 4 号 p. 394
    発行日: 1990年
    公開日: 2009/08/21
    ジャーナル フリー
feedback
Top