地学雑誌
Online ISSN : 1884-0884
Print ISSN : 0022-135X
ISSN-L : 0022-135X
77 巻 , 3 号
選択された号の論文の7件中1~7を表示しています
  • 野上 道男
    1968 年 77 巻 3 号 p. 125-140
    発行日: 1968/06/25
    公開日: 2009/11/12
    ジャーナル フリー
    The Cordillera Real, divide between the Altiplano and Yungas drainage basin, is located to the east of the Bolivian capital, La Paz. This high range has experienced violent glaciations in three times, which are denominated by the author as Pata Antigua, Pata Nueva and Milluni glacial age. Many glaciers yet remains around high peaks in the central parts of the range. Post-Milluni stage is divided into six sub-stages (M1, M2, …… and M6). All cirques now free from ice have been formed in the latest glacial age, Milluni.
    In this paper the author analyzes by statistical method some factors related to the altitudinal distribution of glacial phenomena.
    90 glaciers and 79 cirques analyzed in this paper are located in the National Map of Bolivia, sheet No. 5945 IV, Lago Khara Kkota, in scale of 1 : 50, 000, which covers the central parts of the Cordillera Real. Figure II shows the distribution of the above glaciers and cirques. Altitude was read from contour-lines, and area was measured with a polar planimeter in the original map of Figure II. Data were listed up in Tables II-1 and II-2.
    Correlation coefficients between the altitudinal distribution of glacial phenomena and some factors shown in Tables IV-1 to IV-7 were examined by the method of the t-test of significance. The conclusions are as follows.
    1) The large-sized glaciers are found around the higher summits, and small ones around the lower summits.
    2) The ice-tongues of large-sized glaciers reach down to low altitude.
    3) Neverthless it cannot be concluded that the glaciers around the high summits would reach down to low altitude.
    4) The distance of retreat of the ice-tongues after the sub-stage M6 is proportional to the size of the glaciers. From this result, it may be concluded that the ice-tongues of large-sized glaciers are more sensitive to the fluctuation of climatic circumstances.
    5) Altitude of the cirque-bottoms becomes higher in proportion to the height of summits around them. A great number of the cirques are located by 150 m to 550 m lower than the summits. It is inferred that the cirques were not formed concordantly with the level of snow line. A lower limit of the altitudinal distribution of the cirque-bottoms should be considered as the altitude of ancient snow line.
    The conclusions of the t-test of mean values of the altitude of glacial phenomena are as follows.
    1) Glacial phenomena reach lower in the southern than in the northern slopes. This is probably caused by the fact that the southern slopes are hindered from solar radiation by heavy clouds in the summer when the southern slopes should normally receive more solar radiation.
    2) Glacial phenomena are found higher in the Altiplano than in the Yungas drainage basin. In is because the easterly snow-bearing winds are checked against the barrier of the Cordillera Real.
  • 砂川 一郎
    1968 年 77 巻 3 号 p. 141-154
    発行日: 1968/06/25
    公開日: 2009/11/12
    ジャーナル フリー
    Nakaya wrote a poem in which he says “Snowflake is a letter to us from the sky”. If expressed similarly, mineral crystals in nature are the letters to us from the depth of the earth. They convey the message telling us what has happened under the earth, what was the conditions when they were grown, and what they have experienced since they born. It is clearly worth doing our best to read these letters. As Nakaya tried to read the message that snowflakes convey by studying their crystal morphology, we can obtain much information through detailed studies of the nature of crystals. Surface microstructure of crystal faces, zonal structures inside a crystal, distribution of foreign crystals and lattice defects, as well as impurity atoms, in addition to crystal morphology, will serve as useful key codes to decode the letters.
    In this paper, diamond crystals are used as an example how to decode the letter from deep under the earth. Analysis of crystal morphology of diamond suggest that natural diamonds were grown under near-equilibrium conditions, whereas synthetic crystals under the conditions apart from the equilibrium. Universal occurrence of rounded crystals in natural diamonds suggests that they have experienced dissolution process while they were transported to the earth's surface from the depth, and that the speed of transportation was much higher than our general conjecture. It is also conjectured that diamond will occur only in continental shield and not in the orogenic zones. Observations on the surface microstructures of diamond crystals shows that diamonds were grown from solution phase by condensation and neither from melt phase nor by solid state recrystallization. Zonal structures revealed by chemical etching show that the growth of diamonds was carried out by layer spreading mainly on {111} and that the growth history of individual crystals was very complicated. During the whole history of growth, crystals have experienced partial dissolution, changes in growth speed as well as the rate of impurity adsorption. Recent observations on the nitrogen platelets in natural diamond crystals give an idea that diamond crystals have experienced annealing stage after they were formed, and that the possible origin of carbon of diamond would be carbonaceous material deposited on the ocean bed, which was then transported by an active thrust or heat flow to the depth of 5 to 7 hundreds km, where it was crystallized as diamond. These considerations are mainly based on the hypothesis on the origin of diamond which has recently been proposed by F. C. Frank.
  • 井関 弘太郎, 守屋 以智雄
    1968 年 77 巻 3 号 p. 155-165
    発行日: 1968/06/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 杉村 暢二
    1968 年 77 巻 3 号 p. 166-174
    発行日: 1968/06/25
    公開日: 2009/11/12
    ジャーナル フリー
    The results of the author's study on the structure and location of the stores on Central Shopping Streets (C. S. S.) are summarised as follows :
    (1) The stores closely linked to C. S. S. in each structure are the ones, whose covering articles are less bulky, precious, fashionable and ornamental things, such as ladies' imported articles, ladies' clothes, shoes, cakes, musical instruments, pouches, and watches and precious metals.
    (2) Department stores have a tendency to be found on C. S. S. in the cities with more than 150, 000 population, and amusement equipments (Pachinko, cinema etc.) on C. S. S. in the medium-sized cities and large cities with 150, 000400, 000 population, and then banks and commercial firms on C. S. S. in the small cities with less than 150, 000 population or the mammoth cities with more than one million population.
    (3) Location of the speciality stores on C. S. S. such as dealers in ladies, pouches, musical instruments etc. tends to be arranged in groups with their connected stores, with the increase of city population.
  • ヒンデリンク J.
    1968 年 77 巻 3 号 p. 175-180
    発行日: 1968/06/25
    公開日: 2010/04/23
    ジャーナル フリー
  • 1968 年 77 巻 3 号 p. 192
    発行日: 1968年
    公開日: 2009/11/12
    ジャーナル フリー
  • 大矢 雅彦
    1968 年 77 巻 3 号 p. Plate1-Plate2
    発行日: 1968/06/25
    公開日: 2009/11/12
    ジャーナル フリー
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