第四紀研究
Online ISSN : 1881-8129
Print ISSN : 0418-2642
ISSN-L : 0418-2642
20 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
  • 東 洋一, 藤井 昭二, 畑中 〓, 竹山 憲市
    1982 年 20 巻 4 号 p. 271-280
    発行日: 1982/01/20
    公開日: 2009/08/21
    ジャーナル フリー
    Beachrocks were found at two localities in the Hokuriku region, Central Japan. One beachrock locality is Oniu on the Echizen coastal area, Fukui City, Fukui Prefecture. Another beachrock locality is Awazu-cho, Suzu City in the northeasthern part of the Noto Peninsula. The beachrock is composed of granule, sand-size particles and shells. It can be stated that the beachrock corresponds with the intertidal beachrock reported by TAKENAGA (1965). The 14C age of the beachrock, collected at the sea level altitude of 1.2m in the Echizen coastal ares is 3, 950±80 y.B.P. The 14C age shows that this beachrock could be formed during the Jomon-transgression. Furthermore, the locality of the beachrock in Suzu City may be regarded as the northernmost position of such rock in Japan.
  • 小泉 武栄, 柳町 治
    1982 年 20 巻 4 号 p. 281-287
    発行日: 1982/01/20
    公開日: 2009/08/21
    ジャーナル フリー
    The purpose of this paper is to clarify the present and past periglacial debris-production in the alpine zone of Japanese high mountains. The studied areas are on the main ridge and its surroundings of Mt. Hinokiodake (2, 728m) and Mt. Nigorizawaôtake (2, 724m) located in the central part of the Central Japan Alps which is composed of granodiorite. Forest line runs at about 2, 650m. The results are summarized as follows:
    1. Debris-production is closely related to the density of joint developed in the base rock. Joints are classified into 3 classes (A-C), according to their shape and size. Both A and B class joints are systematic, but with respect to intervals the former is not less than 1m, whereas the latter is about 40-60cm. C class joints are nonsystematic, and their intervals are about 8-12cm or less.
    2. C class joints are mostly open fissures. The places where these joints are developed coincide with fault-crushed zones and show high joint density of 20-35/m. These places are now frost-splitted and supply a small amount of fresh debris. The existence of debris fields on the ridge and taluses can be regarded as the result of such supply (Fig. 2).
    3. The places where A and B class joints are developed show low joint density of 2-10/m. Both class joints are tight in general and now stable, because frost-splitting along these large joints is presumably impossible under the present climatic conditions. Therefore fresh debris are scarcely produced in such places.
    4. Possibly during the Last Glacial Age, however, all three class joints were opened by active frost action under the cold climate and a large amount of debris containing massive blocks of 1-3m in diameter was produced from bedrock. To the west of the main ridge, these debris was transported by active solifluction and formed block fields. Debris-covered gentle slope was developed through these processes. This slope is now stabilized and covered with vegetation.
  • 辻 誠一郎, 南木 睦彦
    1982 年 20 巻 4 号 p. 289-304
    発行日: 1982/01/20
    公開日: 2009/08/21
    ジャーナル フリー
    大磯丘陵北東部の土屋地域に分布する約14.5万~約11.7万年前の吉沢層の大型植物化石・花粉化石の群集を調べた結果;
    1. 下部のSB-0からSB-3は大型化石として主にSapium sebiferum・Aleurites cordata・Vitex cf. cannabifolia・Paliurus・Stephania japonica を, 上部のKlp-2以降は主に Cryptomeria japonica・Alnus japonica・Berchemia を普遍的に産した.
    2. 花粉化石の層位による産状から, 下位よりK-I, II, IIIの花粉化石群集帯を区分し, K-I帯はa, b両亜帯に細区分した. K-I, II, IIIを中井町才ヶ戸のKa-III, IV, V~VIの各帯にそれぞれ対比した.
    3. 大型化石・花粉化石の層位による変動を総合し, Klp-2を境として下部の吉沢-I植物化石群集帯と上部の吉沢-II植物化石群集帯を設定した. 前者には暖温帯性の植物群が含まれるのが特異であり, 後者は暖温帯性植物群を欠き Cryptomeria japonica・Alnus japonica が卓越するのが特異である.
    4. 植物化石群集の変遷は, 従来までに報告された古地理の変遷を支持し, 特にK-II帯での Quercus (Cyclobalanopsis)・Celtis-Aphananthe-Trema などの暖温帯性植物群の生育から, Klp-1の時期を吉沢期の最高海水準期とする従来の見解を支持した.
  • 新潟古砂丘グループ
    1982 年 20 巻 4 号 p. 305-309
    発行日: 1982/01/20
    公開日: 2009/08/21
    ジャーナル フリー
  • 会田 信行
    1982 年 20 巻 4 号 p. 311-317
    発行日: 1982/01/20
    公開日: 2009/08/21
    ジャーナル フリー
  • 松島 義章
    1982 年 20 巻 4 号 p. 319-323
    発行日: 1982/01/20
    公開日: 2009/08/21
    ジャーナル フリー
  • 熊木 洋太
    1982 年 20 巻 4 号 p. 325-327
    発行日: 1982/01/20
    公開日: 2009/08/21
    ジャーナル フリー
  • 池田 碩, 大橋 健, 植村 善博
    1982 年 20 巻 4 号 p. 329-330
    発行日: 1982/01/20
    公開日: 2009/08/21
    ジャーナル フリー
feedback
Top