地学雑誌
Online ISSN : 1884-0884
Print ISSN : 0022-135X
ISSN-L : 0022-135X
91 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
  • 浜野 一彦
    1982 年 91 巻 2 号 p. 69-87
    発行日: 1982/04/25
    公開日: 2010/10/13
    ジャーナル フリー
    The geological formations of Mt. Fuji are composed of Pre-Miocene, Miocene, Pliocene and Komitake, Fuji volcanic ejecta.
    The following table shows the geological formations of this region.
    Pre-Miocene, Miocene and Komitake volcanic ejecta lie beneath Mt. Fuji. These rocks are the foundation of Fuji volcano.
    The first building of Fuji volcano started by Kofuji volcanic mudflow which covered the Komitake volcano and older rocks. The second eruption is made up of a sequence of Younger volcanic ejecta, which cover on alluvium sequence.
    The sequence of ejecta is L1-T1-L2-T2-L3-L4-T3 layers, except for L4 and T3 layers they all erupted from summit fire crater. L-layer is composed of the lava and tephra alternation and T-layer, which has the most of tephra. These limits make up the stratified volcano.
    The flanks of mountain are sculptured by a number of radial valleys but they not have surface streams. The largest valley is “Osawa” and the second is “Yosidaosawa”, both integrated these valleys are now growing. These valley are eroded by streams of the heavy rainfall, flow of underground water and by snowslides. Osawa is a V-type erosion valley and Yoshidaosawa is a U-type wallerosion valley.
    On the flank of the mountain, rainwater sinks into the ground and is stored on the surface of the unpermeable layers (Kofuji volcanic mudflow) as the underground water. It runs downward and flows out at the mountain foot. From the cliff, which outcrips at the top of Yoshidaosawa, large rock fragments fall and roll on the valleyfloor. Summer in 1980, twelve persons were killed by such rockfall. This rockfall happened by the increase of the undergroundwater pressure which made the rock fragments on the near cliff unstable and caused the disasterous rockslides.
  • 伊藤 真人
    1982 年 91 巻 2 号 p. 88-103
    発行日: 1982/04/25
    公開日: 2010/10/13
    ジャーナル フリー
    Several cirques and glacial throughs around the Migimata, Gamata Valley on the western slope of the Yari-Hotaka Range have been studied by some geomorphologists (IMAMURA, 1940; SHIKI, 1970, etc.; IOZAWA, 1972, etc.). The author has newly investigated this area in detail. The distribution of glacial topography in this area, clarified through field survey and aerophoto-interpretation, is shown in Fig. 2, 4 and 5. Judging from the location of terminal moraines, the difference of the degree of dissection of glacial landforms, four stages could be recognized. They are named, from older to younger, Takitani, Yaridaira, Hidazawa I and II stages respectively. They seem to be synchronous to the stages which were proposed by KOBAYASHI, 1958 or by IOZAWA, 1972 in the Yarisawa Valley and Yokoo Valley at the eastern side of the Yari-Hotaka Range. The altitude of the reconstructed glacial snout is same at the both sides of the Yari-Hotaka Range in the early two stages, while it is higher at the western side in the later two. The difference in the direction to the snow bearing wind should be main factors which cause the altitudinal difference of glacial snouts at the both sides of the Yari-Hotaka Range. At the western (windward) slope, most of snow was blown out by the strong wind, while at the eastern (lee) slope, snow accumulation was much more favorable. During the later stages when the snowline had relatively raised, the difference of conditions on the both side of slopes mentioned above should have played a decisive role for determining the glacial distribution.
  • 平川 一臣, 野上 道男, 小疇 尚, 今泉 俊文
    1982 年 91 巻 2 号 p. 104-123
    発行日: 1982/04/25
    公開日: 2010/10/13
    ジャーナル フリー
    It is well known that the large lake, named Balivian, had developed during the Pleistocene in the Bolivian Altiplano, since the study by Bowman in the beginning of this century. Although considerable attention has been paied to this Paleo -Lake, comparatively little is known about its cause of expansion and diminishing, chronology and even the precise distribution. From the geomorphological and stratigraphical survey of the lacustrine and river terraces in the valley of the Rio Desaguadero (Fig.1) where the southern part of the Lake Balivian had occupied, the following conclusions are drawn.
    A series of lacustrine terraces can be divided into four levels by means of the former shoreline topography, paleo-reddish soil, diatomite and pumice fall deposits. Distribution of each terrace is shown in the Figures of 2-1, 2-2 and 2-3. It is apparent that each lacustrine terrace indicates the different extent of the Lake Balivian during the different stages (Fig. 8). The maximum expansion of the Lake was recorded as the highest Tiwanaku (T) Terrace with the height of former shoreline of 3865-3870m above sea level. The T Terrace is composed of thick deposits, the lower part of which is characterized by the fanglomerates supplied from the large tributaries such as the Rio Mauri and the Rio Pontesuero in contrast to the well stratified lacustrine silts and clay of the upper part (Fig. 3). Of the succeeding lacustrine terraces, the Guaqui (G) Terrace is formed through the transgression into the forme r valley landforms dissecting the older terracetopographies (Fig. 5). The Machaca (Ma) Terrace and the Desaguadero (D) Terrace are probably strath terrace. The lacustrine terrace development has apparently controlled by the fluctuation of the Lake Balivian, which is given in the Figure 6.
    There are also four levels of fluvial terraces, which should be correlated with the lacustrine terraces each other, based on the stratigraphical (Fig. 3) and the geomorphological (Fig. 7) data.
    It must be stressed that the expansion of the fluvial depositional surface caused by the tributaries resulted in damming up the valley of the Rio Desaguadero where the coaser fanglomerate could not be transported. According to the stratigraphical data in the vicinity of western foot of the Cordillera Real near La Paz, the cyclic development of fanglomerate and glacial deposits can be established as shown in Figure 6. Consequently, it is quite possible that the Lake Balivian had developed under the environment of alluvial fan formation during the Interglacial ages.
    As the fluctuation of the Lake represents well an evolutional and chronological arrangement with the other data on paleo soil, glaciation in the Cordillera Real and fluvial activity, it should have been indirectly affected by the climatic changes. However, the stage of high lake level demonstrates the Interglacial age and that of low one the Glacial age. In this respect, the Lake Balivian is quite different from the so-called glacial lakes.
  • 川辺 鉄哉, 原 克己, 前田 四郎
    1982 年 91 巻 2 号 p. 124-126
    発行日: 1982/04/25
    公開日: 2010/10/13
    ジャーナル フリー
  • 小林 貞一
    1982 年 91 巻 2 号 p. 127
    発行日: 1982/04/25
    公開日: 2010/10/13
    ジャーナル フリー
  • 石山 洋
    1982 年 91 巻 2 号 p. 128-131
    発行日: 1982/04/25
    公開日: 2010/10/13
    ジャーナル フリー
  • 諏訪 彰
    1982 年 91 巻 2 号 p. 131-132
    発行日: 1982/04/25
    公開日: 2010/10/13
    ジャーナル フリー
  • 浜田 隆士
    1982 年 91 巻 2 号 p. 132-134
    発行日: 1982/04/25
    公開日: 2010/10/13
    ジャーナル フリー
  • 松田 磐余
    1982 年 91 巻 2 号 p. 135-136
    発行日: 1982/04/25
    公開日: 2010/10/13
    ジャーナル フリー
  • 浜野 一彦
    1982 年 91 巻 2 号 p. plate1-plate2
    発行日: 1982/04/25
    公開日: 2010/10/13
    ジャーナル フリー
  • 伊藤 真人
    1982 年 91 巻 2 号 p. plate3-plate4
    発行日: 1982/04/25
    公開日: 2010/12/22
    ジャーナル フリー
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