地学雑誌
Online ISSN : 1884-0884
Print ISSN : 0022-135X
ISSN-L : 0022-135X
84 巻 , 2 号
選択された号の論文の6件中1~6を表示しています
  • 浅間 一男
    1975 年 84 巻 2 号 p. 55-70
    発行日: 1975/04/28
    公開日: 2009/11/12
    ジャーナル フリー
    In this paper the author discusses the rise of the four paleobotanical provinces in the latest Paleozoic era and the cause of their disappearance in the latter part of the Triassic period.
    It was the late Silurian period that the vascular plants advanced onto the land for the first time. Through the Devonian period these plants attained remarkable evolution and laid the foundation for the great development of plants in the Carboniferous period.Since the late Silurian period up to the time of the early Carboniferous Lepidodendropsis flora, the plants had a strong uniformity, with same genera or same species widely distributed from Spitsbergen in the north to the southernmost tip of South Africa. With the appearance of glaciers in the late Carboniferous period, the plants began to show some regional characters, and during the Permian period four distinct floral provinces, in the east, west, north and south, come into existence. The Euramerian province in the west of the equatorial zone was represented by the Euramerian flora which continued from the Carboniferous plants. In the east there was the Cathaysia province represented by the Gigantopteris flora consisting mainly of Gigantopteris nicotianaefolia, Bicoemplectopteris hallei and Lobatannularia heianensis. In the Gondwana province of the Southern Hemisphere, the Glossopteria flora (Gondwana flora) consisting chiefly of Glossopteridales made its appearance, while in the Northern Hemisphere there was the Angara province represented by the Angara flora characterized by such genera as Angaropteridium, Angaridiunz, Paragondwanidium and Glottophyllum.
    The equatorial zone of those days can be located on the map by plotting the equator obtained from the paleomagnetic study (Fig. 3). It is inferred from the map that the Euramerian flora and the Cathaysia flora were distributed roughly along the equatorial zone, the Gondwana flora was distributed encircling the South Pole, and the Angara flora was in the vicinity of about lat. 30°-40°N.
    According to the author's study, the simple leaf of Gigantopteris and Glossopteris was derived from the pinnate leaf either by fusion or enlargement of segments which took place when the plant growth was retarded by the severely changing environment. The fact that the Cathaysia flora had simple-leaf Gigantopteridales indicates that the harsh environment caused repeated fusion of leaf, eventually resulting in the formation of simple leaf, whereas the appearance of simple-leaf Glossopteridales in the Gondwana flora means that the much deteriorated environment caused enlargement repeatedly so as to form the simple leaf.
    When the greater part of the Gondwana flora is occupied by simple-leaf plant, no simple leaf is found in the Angara flora. This seems to suggest that the environment of the Angara province in the north was milder than that of the Gondwanaland in the south.
    Likewise, the Euramerian province in the west was apparently in a milder environment than the Cathaysia province in the east, because the simple-leaf Gigantopteridales are found in the Cathaysia flora while no simple leaf occurs in the Euramerian flora.
    The severity of the environment of the Gondwanaland is attributed to low temperatures as evidenced by the appearance of glaciers, whereas in the Cathaysia province the environmental severity is due to the increasing annual range of climate and the aridness as the land gradually became a continent.
    Thus, the results of the paleobotanical study and the paleomagnetic study seem to be in good accord.
    It can be concluded, therefore, that the rise of the four different floral provinces toward the end of the Paleozoic era is ascribed to the upheaval of the land, on account of which the continental climate came to prevail, the glaciers formed in the Southern Hemisphere and the equatorial zone turned arid.
  • 野間 三郎
    1975 年 84 巻 2 号 p. 71-83
    発行日: 1975/04/28
    公開日: 2009/11/12
    ジャーナル フリー
    The ' center and periphery ' concept appeared anywhere in RATZEL's works. Cultural as well as pheical phernomena were viewed by him from the standpoint of 'center and periphery'. Convincing explanations were thus given to shorelines, snowlines, cities, cultures, national boundaries, etc.
    In place of the hitherto morphological observation, this way of viewing, which is a functional observation, lead RATZEL to the development of a new discipline of study.
    The ' center and periphery ' observation was kept rather in the background in RATZEL. Instead, three concpts of ' space ', ' movement ' and ' location ' were placed in the foreground as basic concepts on which RATZEL's thoughts and ideas were constructed. It can be conceived, however, that the three concepts are in fact welded into one system by way of the center and periphery ' observation.
    Although RATZEL himself does not seem to have been well conscious of it, the center and periphery' observation has two view-angles, that is, 1) differentiation from center to periphery, and 2) diffusion of energy from center to periphery. The former is to a morphological observation as the latter is to a functional observation.
    It is known that such view-angles, which are well demonstrated in the RATZEL's ' movement theory', can be traced to the ' migration theory' of M. WAGNER, a biologist. In contrast to DARWIN, who advocated progressive evolution, WAGNER put an emphasis upon spatial differentiation. When RATZEL made a morphological observation, he focussed on the differentiation, but when his attention was directed toward a mechanism, he stressed the diffusion.
    The RATZEL's diffusionistic view in discussing physical phenomena and anthropogenic cultural traits has no doubt a great influence upon contemporary geographers. This also suggests that it is not relevant to. think RATZEL was under an influence of DARWIN.
    With full of affluent touches to describe abundant, variegated facts and materials, the RATZEL's work manifest that he was unable to control his overflowing thoughts and ideas. He may as well have been an artist who turned to be a scientist. The orderly arrangement by logic seems to have fallen short of completeness.
    The present article clarifies that the unifying artery of the three concepts of space ', movement ' and location ' is by itself the center and periphery ' model. It also illustrates the differentiation and diffusion ' concept basically support RATZEL and that it appears a central concept again in contemporary geography.
  • 茂木 昭夫, 岩崎 博
    1975 年 84 巻 2 号 p. 84-94
    発行日: 1975/04/28
    公開日: 2009/11/12
    ジャーナル フリー
    A number of sand waves and mega-ripples are found on two submarine sand banks (Inosakinotsugai and a non-named bank eastward of Koyoshima) in Bisan Seto means of a side-scanning sonar (Bottom Sonar) and echo sounding.
    Straight type sand waves developed on Inosakinotsugai and winding typed ones developed on the non-named bank. The former are arranged at right angles to the direction of the strongest tidal stream flowing over Inosakinotsugai. The latter show a composite pattern consisting of main sand waves having NW-SE trend formed by the strongest tidal stream flowing along the south wing of the bank and subsidiary sand waves having NNE-SSW trend generated by the strongest tidal stream flowing along the north wing of the bank.
    On the other hand, those banks have areas of mega-ripples independ of the areas of sand waves, though both areas are overlapping at their boundaries. Mega-ripple areas cor respond to the area of granule and gravel, and sand wave areas correspond to the area of coarse and medium sand.
  • 志保井 利夫
    1975 年 84 巻 2 号 p. 95-106
    発行日: 1975/04/28
    公開日: 2009/11/12
    ジャーナル フリー
    The periglacial phenomena in Kitami District, NE-Hokkaido, is classified into three groups ; (a) those above 1700m Si. accompanying sorted polygons, etc., (b) those above 300m with severe frost-shattering, and (c) those below 300m, where verved clay and its involutions are observed. The ice-shove ridges along the beach of Okhotsk Sea is different characteristically from inland phenomena, but here it is included in the (c) group.
    Hirayama (1775m) is located at the back-bone mountain, east of Daisetsu Mountain mass. The summit is occupied by a wide altiplanation terrace, and the lee-side gentle slope from westerlies shows nivation niches, and sorted circles. It is above the coniferous forest line, and locally known with its alpine flower gardens.
    The ice-shove ridges along Okhotsk beach are formed by the sea-ice pushed up on the sandy beach by the drag force of surface wind during the winter season, and remain there for about four months. The sand bulldozered by the front of sea ice from the coastal sea bottom contains more grains of well polished, rounded agate, opal, chalcedony, and jasper than the normal beach sand.
    The above two phenomena are directly connected with the climatological condition which is governed by the prevailing cold westerlies in winter, while the frost-shattering etc. of group (b) are controlled by the combination of complex microclimatological and microgeomorphological conditions.
  • 前島 郁雄
    1975 年 84 巻 2 号 p. 107-108
    発行日: 1975/04/28
    公開日: 2009/11/12
    ジャーナル フリー
  • 市川 正巳
    1975 年 84 巻 2 号 p. Plate1-Plate2
    発行日: 1975/04/28
    公開日: 2009/11/12
    ジャーナル フリー
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