第四紀研究
Online ISSN : 1881-8129
Print ISSN : 0418-2642
ISSN-L : 0418-2642
1 巻 , 2 号
選択された号の論文の4件中1~4を表示しています
  • 井関 弘太郎
    1958 年 1 巻 2 号 p. 39-44
    発行日: 1958/01/25
    公開日: 2009/08/21
    ジャーナル フリー
    In Japan, the changes of the sea-level seem to have occurred during the late-Quaternary, as are shown in the following table.
    sea-level at
    Last Glaciation about -80m.
    Earliest Jomon stage (about 4000 B. C.) -10∼15m.
    Early or middle Jomon stage (3500-2500B. C.) +3∼5m.
    Late Jomon stage (about 1000 B. C.) 2∼3m.
    Late Yayoi stage (about A. D. 200) ±0m.
    These are indicated by correlations between the late-Quaternary formations and the topographical features, and the discovery of the prehistoric remains.
    The bedrock floors of large river valleys are filled with tha late-Quaternary deposits usually at 60-80 meters below the present sea-level. Ordinarily, they are covered with the fluviatile gravel beds of about 10 meters thick. These are supposedly formed during the time of the low sea-level of the latest glaciation. Near the mouth of large rivers, the gravel beds generally are found at 50-70 meters deep, with some exceptional instances, such as Setouchi region and Echigo plain. In some districts, the seaward extension of the gravel beds is connected with the abrasion platforms off-shore at a depth 70-100 meters below the present sea-level. This shows that the sea-level, before the Holocene marine transgression, was about 70-80 meters lower than the present.
    There are some fresh-water shell middens formed in the earliest Jomon stage, in some parts of the islets of the Seto Inland Sea. This shows that the sea-level then was about 15 meters lower than the present. But in Kanto district, it has been known that the level was at about -10 meters.
    Judging from the distribution of the middens in Kanto district, the highest sea-level was supposed to have taken palce in the early Jomon stage. However in Nobi plain, it was found to have occurred in the middle Jomon stage. The marine deposits are now discovered at a level few meters high above the present sea-level, showing that the sea-level then was higher than today.
    The sea-level dropped soon after its maximum rise, and, consequently, the new coastal plains were eroded by the extended rivers. But the river beds are now found at about 3 meters below the present sea-level, showing the sea-level to be 2 or more meters lower than the present.
    During the later Jomon stage and the Yayoi stage, the sea-level finally rose to its present height, since the channels were filled up with marsh deposits. Paddy-field rice plant was introduced into Japan about that time and it was cultivated at the first stage in marshy land without irrigation.
    Fluvial deposits covering the surface of the marshy plains and the greater part of the marine deposits at less than 5 meters above sea-level began to form after the middle Yayoi stage. These deposits are less than few meters thick.
  • 山本 武夫
    1958 年 1 巻 2 号 p. 45-48
    発行日: 1958/01/25
    公開日: 2009/08/21
    ジャーナル フリー
    The advances and retreats of the Alpine glaciers show a surprising correspondence to the up and declined states of the tree-growths at Arlieshan Mt. (23°30′N 120°48′E 2676M) in Formosa, as shown in Fig. 3. It is supposed that the intensified state of jet stream would result the retreat of glaciers in the Alps, activating the lateral mixings of cold and warm air, while, in the Far East, the stronger jet would repress the amount of summer precipitations of the south-eastern monsoons on which tree-growths might depend. (See Fig. 2)
  • 塚田 松雄
    1958 年 1 巻 2 号 p. 48-58
    発行日: 1958/01/25
    公開日: 2009/08/21
    ジャーナル フリー
    日本における主要四地点の花粉分析結果から後氷期の森林・気候変遷を論じた(Fig. 2) その結果. 下層より, 寒冷期は今より-3℃低温, 温暖期は今より2°-3℃温暖であつた (Fig. 3) 更に世界各地の花粉分析結果と対比した時日本でも同様な気候変遷がみられる. 堀の泥炭堆積速度, Blytt-Sernander の時代決定, ヨーロツパ, 北アメリカ等の花粉分析の資料を考慮して, 寒冷期と温暖期の境界, 温暖期と減暖期の境界の絶対年代につき Table 1の如く整理した. 前者は6000-5500年, 後者はB. C. 2000-1000年となる.
    この温暖期は東京湾の海進時に, 減暖期は海退時に対比され, 繩文と弥生時代の境界はB.C. 2000-1000頃となる. 尚C14による繩文晩期及び繩文前期の丸木舟の破片の測定は, 前者がB.C. 1122±180年, 後者がB. C. 3145±400年となり略々一致する.
  • 高井 冬二, 鹿間 時夫, 井上 正昭, 長谷川 善和
    1958 年 1 巻 2 号 p. 58-61
    発行日: 1958/01/25
    公開日: 2009/08/21
    ジャーナル フリー
    In the spring of 1955 a lower jaw of both sides with third milk molar was excavated from a fissure deposit of Kawai limestone quarry at Yage, Iinoya-mura, Inasa-gun, Shizuoka Prefecture. Judging from the occurrence of Palaeoloxo don namadicus naumanni, having been described about thirty years ago from the Sahanma shell beds, it seems to be probable that this material must belong to the above subspecies, one of the most common subspecies in the Japanese Pleistocene. As the occurrence of milk teeth is the first example in Japan, they are described here. The geological age of the fissure deposit is considered to be the late Pleistocene (J2) and not to be the latest (J3).
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