地学雑誌
Online ISSN : 1884-0884
Print ISSN : 0022-135X
ISSN-L : 0022-135X
95 巻 , 1 号
選択された号の論文の9件中1~9を表示しています
  • 増田 富士雄
    1986 年 95 巻 1 号 p. 1-26
    発行日: 1986/02/25
    公開日: 2010/02/25
    ジャーナル フリー
    Basic studies of the elemental composition in marine carbonates are carried out to estimate paleoenvironments, such as, paleotemperature and paleosalinity.
    (1) A crystal structure control model is introduced to trace element partition between marine carbonates and seawater. Divalent alkaline earths and transition elements occupy regularly the lattice site, while monovalent alkali elements show no tendency to occupy the lattice site in the crystal structure of calcium carbonates.
    (2) Four clusters of marine carbonate skeletons, which are the most basic units for the paleoenvironmental research, are dividable based on the strontium and magnesium contents.
    (3) Detailed ontogenetic variations of elemental composition in a single shell are newly clarified. Some elements, such as, magnesium, strontium, sodium, and lithium, show a typical seasonal growth variation. These elements give a possibility as paleothermometer.
    (4) The ontogenetic variation can be simulated by the following optimum temperature model : Every species indigenously have an optimum temperature value of calcium carbonate metabolism. The intensity of the metabolism gradulally decreases toward lower or higher temperature from the optimum value.
    (5) A optimum condition model, which is expanded from the optimum temperature model, also gives a synoptic explanation for the complex phenomena of empirical relations between elemental content of skeletal carbonates and environmental factors.
  • 内藤 正典
    1986 年 95 巻 1 号 p. 27-45
    発行日: 1986/02/25
    公開日: 2010/04/23
    ジャーナル フリー
    Ecumene in arid zone finds itself within limited space ; limited as such urban and agricultural activities often share water for drinking and irrigation. Traditionally city and its surrounding oasis have been successful in managing water in coordination.
    After World War II, many Middle Eastern countries became independent ; population of major cities has been rapidly increased, mainly because of rural-urban migration. Expansion of urban fringe directly affected adjoining oasis villages, so that ecological balance between them collapsed.
    Although a number of monographs have been written by geographers and historians, they often study each individual city or oasis as a distinct and independent subject. Under these circumstances it is necessary to regard both city and oasis as an integrated entity region, each of them often affects the other in quite a dynamic way. In a case of Demascus city and its surrounding oasis, a typical example of pseude urbanization can be observed.
    The oasis, located in Badiya al-Sham (The Syrian Desert), is divided into two parts ; the orchards of Ghuta and the steppe of Marj. There are approximately ninety villages in the oasis, which used to be subordinated to absentee landlords lived in the city of Damascus prior to the Land Reform of 1958.
    After the Land Reform, such an absentee landownership dissapeared. In accordance with the rapid urbanization, however, the villages have started to dissolve in the western fringe of the oasis. With the destruction of irrigation canals and the sprawl of residential area into farmlands more and more peasants, especially in younger generation, have been leaving from farming due to urban-rural income differentials.
    The degree of reliance on agriculture is principally determined by size of farms and water supply, but it is different among four subregions in the oasis : oasis-urban fringe, central Ghuta, boundary zone between Ghuta and Marj, and Marj steppe.
    First, in the oasis-urban fringe, the most western part of Ghuta, it has been impossible to continue cultivation during the last ten years.
    Second, the central part of Ghuta is highly productive in fruits farming and, in fact, the agricultural income level per hectar is the highest among the four subregions of the oasis. But, ironically, because of this productivity, each farmyard has been generally subdivided among all the members of family. Consequently, average farming size is now under one hectar, and the peasants are depend upon non-agricultural incom e. The destruction of irrigation canals in upstream forces peasants in the central Ghuta to change their source of irrigation water from surface to underground.
    Third, the boundary zone between Ghuta and Marj, there used to be many swamps and it was wasted land. When the government redistributed the requisited land in this zone at the Land Reform, only a few peasants applied. Therefore a size of five to six hectar was allotted to them. Incidentally, pumping-up of ground water in Ghuta caused drying up of the swamps, and then, cultivation is realized even in winter wet season. Nowadays, the peasants possess enough size of field and get ground water easily in shallow level by motorpumping. The trend of quitting farming is scarce in this area.
    As a result of this pumping activity, Marj area suffers from serious water shortage in both surface and ground water. And lately, in these ten years, among several villages in the western end of Marj, almost all the peasants abondoned their farming to find jobs in Damascus city. But, as Marj on the whole, there is another economic reason why they can not earn enough income from agriculture. That is the reduction of farm size after the Land Reform. Farmlands allotted are under ten hectar, and it was quite insufficient for traditional extensive farming of wheat under feudal landownership.
  • 奥山 育子
    1986 年 95 巻 1 号 p. 46-61
    発行日: 1986/02/25
    公開日: 2009/11/12
    ジャーナル フリー
    Most of the Japanese Islands have experienced intensive rural exodus caused by the rapid economic growth since 1960s. The excellent papers on these migration processes have been published. Comparing with the migration processes since 1960s, those before the World War II had distinctive features in each island. Their studies have no sufficiently advanced because of the difficulties to follow the statistical data. This article aims to analyze the features of migration process in the Hachijou-jima (Hachijou Island) mainly from the beginning of the Meiji period to the World War II.
    The Hachjiou-jima has been historically known as a jail island. The exodus from the island was strictly prohibited in the Edo period, but the agricultural emigration to Mainland villages was allowed in 1777. The economic activities in the Hachijou-jima had based on the traditional sifting cultivation and the commercial production of Kihachi-jou (silky weaving), but the scarcity of economic resources and the agricultural low productivities had historically brought about the overpopulation. This economic structure had not been transformed in the Meiji period. But with the beginning of the colonization of Ogasawara Islands to develop the sugarcane industries, this island had experienced the intensive outmigration since 1890s. The migration process in this first stage has the characteristics as follows :
    (1) The emigrants were not from the peasants of lower classes. They kept the ownership of their agricultural lands and sometimes enlarged it by the purchase even after moving to Ogasawara Islands (Fig. 1 and 2).
    (2) They usually migrated with all family members and their family heads were from younger age-group (Table 3).
    (3) The migration flows to Tokyo or the neighbouring islands were not significant.
    The success stories of migrants in this first stage accelerated the spacial mobilities of islanders. The migrantion flows expanded to Hokkaido, Minamidaito-jima and the Japanese colonies such as Korea, Taiwan and their neighbouring islands. The economic acitivities in the Taisho period were mainly the dairy farming and charcoal making, but they severely suffered from the economic damages after the Great Depression. With the territorial expansion policy in this period, the migration flows of Hachijou islanders also expanded to Japanese colonies such as Mariana, Carolin and Marshall Islands. The features of migration process in the second stage were those as follows :
    (1) Migrants engaged in sugarcane industries as tenants.
    (2) They were from the peasants of lower classes.
    (3) Many of them had experienced the migration to Ogasawara or Minamidaito-jima Islands, or had the relatives in these islands (Fig. 3).
    These migration process came to the end with the opening of the World War II.
  • 松田 磐余
    1986 年 95 巻 1 号 p. 62-63
    発行日: 1986/02/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 石山 洋
    1986 年 95 巻 1 号 p. 64
    発行日: 1986/02/25
    公開日: 2009/11/12
    ジャーナル フリー
  • 増澤 譲太郎
    1986 年 95 巻 1 号 p. 65
    発行日: 1986/02/25
    公開日: 2009/11/12
    ジャーナル フリー
  • マンスハルト W.
    1986 年 95 巻 1 号 p. 66-68
    発行日: 1986/02/25
    公開日: 2010/04/23
    ジャーナル フリー
  • 1986 年 95 巻 1 号 p. 69
    発行日: 1986年
    公開日: 2009/11/12
    ジャーナル フリー
  • 内藤 正典
    1986 年 95 巻 1 号 p. Plate1-Plate2
    発行日: 1986/02/25
    公開日: 2009/11/12
    ジャーナル フリー
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