The Journal of the Geological Society of Japan
Online ISSN : 1349-9963
Print ISSN : 0016-7630
ISSN-L : 0016-7630
Volume 59 , Issue 699
Showing 1-3 articles out of 3 articles from the selected issue
  • Haruhiko KIMUBA
    1953 Volume 59 Issue 699 Pages 533-543
    Published: December 25, 1953
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    An experimental study of the critical current velocity necessary to transport particles is described in this report., The study has clarified the following points: (1) A problem of special importance with regard to the traction of sedimentary particles is the velocity distribution near the part of the particle in relation to its size., Velocity distribution on the upper part of the particle has no direct influence on the traction., (2) The critical current velocity required to start motion of a sedimentary particle can be accurately shown by the mean current velocity from the bottom to the top of this particle at the very instant motion begins., The writer named this mean velocity the "proper critical velocity"., (3) In order to learn the relation between current velocity and particle size, the "proper critical velocity" must be used, because the current velocity varies vertically., The proper critical velocity, "Vp", on a smooth flat bottom is given by the following empirical formula: Vp=kdn where k is a constant, d is the diameter of the particle, n≒1., 5 (corresponds to d≒0., 1∼0., 75mm) 1., 0 (corresponds to d≒0., 75∼3., 5mm)(4) If many particles of the same size exist on the bottom, the Vp of these particles increases owing to the friction between the particles.,
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  • Motoki EGUCHI, Rikii SHOJI, Shun-ichi SUZUKI
    1953 Volume 59 Issue 699 Pages 544-551
    Published: December 25, 1953
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    This paper describes the cyclic sedimentation of the Tertiary coal-bearing formations in the Futaba district, Joban coal field., The Shiramizu group in the district is comprised of the Asamigawa formation, Asagai sandstone and Shirasaka shale, named in ascending order., The Asamigawa formation in this district is characterized by the abundance of coarse-grained sediments which represent eight cycles of sedimentation, separated from each other by an erosional surface or diastem., The sediments of the each cycle consist of conglomerates sandstones, shales and coal seams., These sediments are coarser and thinner than those of the Hanakawa formation in the Isohara district., However, the Shiramizu group, comprised of the Asagai sandstone and the Shirasaka shale, is quite uniform as to lithology and thickness in both areas., The Yunagaya group has a seguence similar to the Shiramizu group and may be divided into five formations: the Nagahata formation, Oyauchi sandstone, Mizunoya sandy shale, Kamenoo shale and Hon'ya shale, listed in ascending order., The cycles of the Nagahata formation are composed of conglomerates, sandstones, shales and thin coal seams., The Oyauchi sandstone, Mizunoya sandy shale, Kamenoo shales and Hon'ya shale constitute a megacycle which for the most part represents a marine facies., The Kasamatsu formation of the Cretaceous Futaba group and the Misawa sandstone of the Shirado group also consist of a cyclic alternation of sandstones, shales and carbonaceous shales with thin coal seams.,
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  • Tsuneo TOMISAWA
    1953 Volume 59 Issue 699 Pages 552-560
    Published: December 25, 1953
    Released: April 11, 2008
    JOURNALS FREE ACCESS
    The stratigraphic sequence in the Susobana-kawa region is as follows: (Quaternary) Terrace deposit Iizuna formation Minochi group (Tertiary)(8) Orihashi formation (7) Nakanogi formation (6) Shimokusukawa formation (5) Arakura formation (4) Machi formation (3) Ju-ni-taira formation (2) Yahagi formation (1) Nishikyo formation The Iizuna formation is principally composed of volcanic detritus., The Tertiary Minochi group represents a great cycle of geosyhclinal deposits which were deposited in the Shigarami basin., The Ju-ni-taira and Machi formations contain many Cyclammina pusilla and other foraminifera, and the Shimokusakawa formation contains Patinopecten healeyi yamasakii, Turritella saishuensis and other mollusca in great abundance., The fossils are a neritic fauna., The principal structural feature of the Susobana-kawa region is the Nishikyo-Kamikusukawa anticline., This anticline is an overturned fold, which becomes an overthrust in the part of the region., And, it is believed that the structure was formed by shearing force which acted in a NW-SE direction.,
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