地学雑誌
Online ISSN : 1884-0884
Print ISSN : 0022-135X
ISSN-L : 0022-135X
89 巻 , 2 号
選択された号の論文の11件中1~11を表示しています
  • 江川 良武, 堀 伸三郎, 坂山 利彦
    1980 年 89 巻 2 号 p. 85-96
    発行日: 1980/04/25
    公開日: 2010/10/13
    ジャーナル フリー
    Even in summer, the cold air, lower than average annual temperature by 10°C, is exhausted from underground through spaces within debris at the sites called “Fuketsu”.
    At the Fuketsu, the subsurface air circulation occurs. In winter, the air is inhaled from lower part of a slope, and exhausted at upper part of a slope. During this kind of the air circulation, the debris is frozen to even 50 m depth. In summer, the air circulation is reversed. The inhaled air is cooled to almost annual average temperature before arriving frozen debris. Due to these processes, debris remaines to be frozen untill autumn and this is the reason why the exhausted air in summer is abnormally cold.
    The common ground condition of the “Fuketsu” is studied by relative comparison of 20 samples, and the result is as follows.
    1) Snow covered districts in winter.
    2) North facing slopes.
    3) Abundantly debris accumulated slopes in front of steep scarps, gigantic landslide area is favorable to this condition.
  • 岡 秀一
    1980 年 89 巻 2 号 p. 97-112
    発行日: 1980/04/25
    公開日: 2010/10/13
    ジャーナル フリー
    In the mountainous regions, so-called wind-shaped trees are frequently used as an effective indicator of wind. But it is a matter for regret that their causality is not always apparent. Therefore, the main purpose of this paper is to determine what is actually the causative factor for deformation of larches (Larix leptolepis) on Mt. Fuji.
    In the first place, the following types of deformation are classified. 1) C type: This is generally low in stature and the trunk seems to creep on the ground. 2) F type: This is a type of deformation which has its crown on one side only. So-called flag-shaped tree. 3) S type: This type shows only a slight degree of deformation.
    Then, the directions and types of these deformed trees are surveyed along 30 routes.(Fig. 1) Their distribution is shown in Fig. 2, which is presented on a circular gragh as a model of Mt. Fuji. But, I can't relate this result with any particular cause. It is only noticeable that there is a great difference in directions between F type and Stype as shown on the 15th route (Subashiri) as an example.
    On the 2nd May, 1970, I observed that the reddened bark on one side of a trunk (Photo. 1), which had been probably formed in winter, corresponded almost exactly to the side on which branches and boughs are lacking. On the other hand, for the purpose of determining wind action, painted plates were set on the trunk of F type tree in four directions so that one of them was faced to the direction of the expected deforming agents.(Photo. 2) They were exposed to wind and preciptation during summer or winter. Consequently after a winter exposure, the plate corresponded to the direction of F type tree was most damaged.(Photo. 3) From these evidence, F type deformed larches are expected to be formed during winter time.
    Now, on the top of the mountain, strong westerly or northwesterly wind prevail in winter.(Fig. 5) But as a result of detailed investigation of meteorological data reported by extraordinary observations on southeast slope during January 1951, it seems that the wind coincided with the direction of deformed trees blows during the night when northwesterly monsoon slightly weaken.(Fig. 8) For the duration of blowing this wind, the vapour tension and air temperature become lower. This colder and drier northwesterliesin winter are thought as an important cause for the F type deformation.
    Different from the other types, the direction of S type deformation indicate southward on the whole. This direction is in good agreement with southwesterlies accompanied with passing of trough or depression.
    From a point of view described above, the distribution of expected wind direction is drown in Fig. 9.
    Emphasizing only on ridges because of probability representing larger scale wind system than in valleys, I drew streamlines along the slopes of Mt. Fuji.(Fig. 10) The figures clearly show the existence of up-current in “summer” and down-current in winter.
    Further, I tried to investigate about the variation of form of trunks with altitude or direction of slopes. The ratios of the height of trunks to the diameter of breast high (H/D) on each routes are calculated and averaged every 50 m high.(Fig. 11) Some character are pointed out in this figure. Namely, two groupes are distinguished by the H/D values around tree limit. Refering to Fig. 12, the extent of C type range likely contributes to the difference between both groupes. In addition, the H/D values do not increase in both groupes from about 100 m below the tree limit. It appears independently of the types of deformation or direction of slopes. This tendency is determined by the distance from the tree limit, and likely related to the increase of tree densities with descending the slopes.
  • 前田 四郎, 渡辺 喜興, 大塚 澄夫, 川辺 鉄哉
    1980 年 89 巻 2 号 p. 113-123
    発行日: 1980/04/25
    公開日: 2010/12/22
    ジャーナル フリー
    房総半島中部で東西に広く分布する清澄層及び安野層の堆積学的, 地史学的研究の基礎として猪ノ川流域の両層の層序を詳細に調査し, また清澄層の層序を太平洋岸の鵜原地域の層序と比較検討した。その結果判明した諸事実や若干の考察とを記してまとめとする。
    1) 清澄層及び安野層は主として岩相に基づきそれぞれ3区分される。すなわち清澄層は礫岩の存否や堆積サイクルを構成する単層の厚さを基準にして下部礫質砂岩部層・中部砂岩部層・上部砂岩部層に区分される。厚さは下部礫質砂岩部層が約45m, 中部砂岩部層が約140m, 上部砂岩部層が約80mと推定される。
    2) 安野層は下位より厚さ95mの下部シルト部層, 厚さ約85mの中部砂岩・シルト岩部層, 厚さ約120mの上部砂岩部層に区分される。猪ノ川流域においては安野層の中部砂岩 ・シルト岩部層中にゴマシオ状凝灰岩を頻繁に挾在し, これに比べ上部砂岩部層中には多くのスコリアを挾むのが特徴である。
    3) 従来, 清澄層及び安野層の層厚に関しては清澄層のそれが安野層のそれに比べて一般的には厚いように考えられていたが (沢田: 1939, 他), 当地域では清澄層の層厚が約265m, 安野層のそれが300~320mで, 安野層の層厚が清澄層のそれよりやや厚いといえる。
    4) 清澄層の層序を太平洋岸の鵜原地域のそれと比較検討した結果, 層厚に関してKi-1 (≒HKt) の層準から安野層の下限までは, 猪ノ川流域の清澄層と鵜原地域のそれとではほとんど変化が認められなかった。
    5) 鵜原地域の清澄層の下部部層には猪ノ川流域の下部礫質砂岩部層に含まれている細礫はほとんどみあたらないので, 岩相に東西で若干の変化がある。
    6) 猪ノ川流域の清澄層全般にわたってみられる炭質物の葉理は鵜原地域においてはやや乏しい。
    7) 当地域の清澄層と安野層とは共に有孔虫化石や石灰質ナンノプランクトン化石はかなりよく産出するが, しかし軟体動物化石は乏しい。
  • 小林 貞一
    1980 年 89 巻 2 号 p. 124-131
    発行日: 1980/04/25
    公開日: 2010/10/13
    ジャーナル フリー
  • 渡辺 光
    1980 年 89 巻 2 号 p. 132-135
    発行日: 1980/04/25
    公開日: 2010/10/13
    ジャーナル フリー
  • 山本 荘毅
    1980 年 89 巻 2 号 p. 136-139
    発行日: 1980/04/25
    公開日: 2010/10/13
    ジャーナル フリー
  • 小林 貞一
    1980 年 89 巻 2 号 p. 140-141
    発行日: 1980/04/25
    公開日: 2010/10/13
    ジャーナル フリー
  • 尾崎 博
    1980 年 89 巻 2 号 p. 141-142
    発行日: 1980/04/25
    公開日: 2010/10/13
    ジャーナル フリー
  • 山口 岳志, 前田 四郎
    1980 年 89 巻 2 号 p. 142-143
    発行日: 1980/04/25
    公開日: 2010/10/13
    ジャーナル フリー
  • 1980 年 89 巻 2 号 p. e1
    発行日: 1980年
    公開日: 2010/10/13
    ジャーナル フリー
  • 松田 磐余
    1980 年 89 巻 2 号 p. plate1-plate2
    発行日: 1980/04/25
    公開日: 2010/12/22
    ジャーナル フリー
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