著者

立平 良三

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.111, no.5, pp.780-782, 2002-10-25 (Released:2009-11-12)

参考文献数

4

著者

生駒 大洋 玄田 英典

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.116, no.1, pp.196-210, 2007-02-25 (Released:2009-11-12)

参考文献数

47

被引用文献数

1

---

Although the mass of oceans on the Earth is a tiny fraction (0.023 wt%) of the bulk Earth mass, the existence of oceans is sufficient to distinguish the Earth from the other planets in the solar system. Water is essential for the origin and evolution of life, the stability of the surface environment, and the evolution of the planetary interior. At present, we have no definite answers to fundamental questions about the origins of water on the Earth. The process by which water was supplied to the Earth is thought to be closely related to the dynamics of the solar system. Because of several uncertainties about the planet formation process (the position of the snow line in the solar nebula, the lifetime of the nebula gas, the timing of the formation of Jupiter, etc.), the origins of the Earth's oceans are still much in question. In this paper, we describe several possible sources of the Earth's water in the solar system and possible processes by which water was supplied to the Earth. Within the context of the modern theory of planetary formation, we discuss several scenarios for the origins of the Earth's oceans.

著者

小藤 文次郎

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.42, no.10, pp.562-563, 1930

著者

浜野 一彦

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.91, no.2, pp.69-87, 1982-04-25 (Released:2010-10-13)

参考文献数

9

被引用文献数

1

---

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.

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.1, no.9, pp.443-444, 1889-09-25 (Released:2010-12-22)

著者

海津 正倫

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.107, no.1, pp.137-141, 1998-02-25 (Released:2009-11-12)

参考文献数

14

著者

保柳 睦美

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.74, no.6, pp.347-350, 1965-12-25 (Released:2009-11-12)

著者

吉野 正敏

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.118, no.6, pp.1221-1236, 2009-12-25

参考文献数

60

被引用文献数

1 2

---

&emsp;The global climate is known to have been relatively warm during the period from the 4th to 10th centuries, although there were slightly different fluctuation patterns locally and regionally. The present article addresses these differences, analyzing the results of previous studies. The warm period is known in Europe as the Medieval Warm Period.<br>&emsp;Evidence in Japan is also found from the 4th century to the 11th century. Because historical age divisions differ between Europe and Japan, the peak of the Warm Period from the 7th to the 10th century is classified as part of the ancient period in Japan. Therefore, the Warm Period in Japan has been proposed to be called the Nara-Heian Warm Period, Heian Warm Period or Little Climatic Optimum.<br>&emsp;Based on the water level changes of Lake Shinji in Shimane Prefecture, the present article discusses the warmer climatic conditions in the Heian Period. It also examines old agricultural settlements in the Tohoku District, northern Honshu. People came from Hokkaido or northern Honshu and cultivated rice in the northeastern-most part of Honshu in the 1st century B.C. It is thought that the effect of the warm current branch flowing along the Japan Sea Coast and emerging on the Pacific side through the Tsugaru Straight had an influence on the distribution of rice cultivation at this early stage.<br>&emsp;Finally, the article shows that the northward shift of the power front of the Central Government (Yamato Chotei) during the 7th to the 9th centuries occurred about 70-80 years earlier in Dewa, an ancient state on the Japan Sea side of Tohoku District, than in Mutsu, also an ancient state on the Pacific side. It is interesting to note, however, that the speed of the northward shift was almost the same on both sides, even though there were different political powers, situations and problems on either side. It is suggested that the northward shift was affected by the warming on the broader space scale.

著者

神津 俶祐

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.24, no.11, pp.754-764, 1912-11-15 (Released:2010-10-13)

著者

小河 正基

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.124, no.1, pp.1-30, 2015-02-25 (Released:2015-03-11)

参考文献数

133

---

Great advances on observational studies of terrestrial planets including our own Earth since the 1990s suggest that we should fundamentally revise our view on the evolution of planetary interiors. It has been implicitly assumed that the mantle of a terrestrial planet evolves quasi-statically due to heat extraction by mantle convection. Tomographic studies on the Earth's mantle together with geologic studies, however, show that the overturn time of mantle convection is on the order of a billion years, which is comparable to the age of the Earth. So the evolution of the Earth's mantle is a dynamic process and the quasi-static model of mantle evolution is no longer tenable. Images of terrestrial planets recently sent from spacecraft suggest that the evolution of terrestrial planets depends systematically on their size, and that the evolution of the Earth should be understood in the context of this systematic relationship. The finding of super-Earths implies that we must figure a way to infer the evolution of these planets from limited information, such as the planetary mass, radius, and the composition of the atmosphere, on the basis of studies on terrestrial planets in our solar system. Geologic studies on Archean continents older than 2.5 billion years show that the tectonic regime of early Earth is qualitatively different from that of modern Earth, so the magmatism-mantle convection system in the Earth must have experienced a regime-transition at some point in its history. More dynamically oriented models of mantle evolution would be useful for predicting how the Earth's mantle evolved at its earliest stages on the basis of observations of other celestial bodies such as the Moon, where the old surface is still preserved. Further refinement of seismic studies on the Earth's interior combined with studies on the properties of mantle materials under high pressures are crucial to improve our understanding of the history of the Earth's interior.

著者

竹之内 耕

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.120, no.5, pp.819-833, 2011-10-25 (Released:2012-01-17)

参考文献数

20

被引用文献数

4 9

---

Geopark is a beneficial tool for regional development that makes use of characteristic natural and cultural resources, such as landform, rocks, animals, and plants, as well as human history, culture, and traditions in an area. Geopark as a system includes promoting regional development based on integrating three fundamental elements of geopark activity, i.e., conservation, education, and geotourism. Itoigawa Geopark was designated a member of the Global Geopark Network with assistance from UNESCO on 22 August 2009. Itoigawa is a small city with a population of about 48,000 located on the coast of the Japan Sea close to mountains. Following its recognition, the citizens of Itoigawa became aware of the international excellence of the nature and culture of the city and developed pride in their hometown. Consequently, work began to construct a new community by promoting the region based on the geopark system. The awareness of the citizens generated the spontaneous ideas and actions needed to construct a comfortable life with good health, education, and economy in the city. Local governments, such as those of cities, towns, and villages, especially in rural areas, have been looking for ways to promote their regions because of Japan's weak economy over the past twenty years. The geopark is expected to be a useful tool for achieving significant regional development in rural areas.

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.26, no.7, pp.565c, 1914

著者

佐藤 暢 熊谷 英憲 根尾 夏紀 中村 謙太郎

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.117, no.1, pp.124-145, 2008-02-25 (Released:2010-02-10)

参考文献数

60

被引用文献数

3 5

---

Mid-ocean ridge basalt (hereafter, MORB) is a final product of melt generated from the partial melting of mantle peridotite, following reaction with mantle and/or lower crustral rocks, fractionation at a shallower crust and other processes en route to seafloor. Therefore, it is difficult to estimate melting processes at the upper mantle solely from any investigations of MORB. In contrast to the restricted occurrence of peridotite of mantle origin in particular tectonic settings (e.g., ophiolites, fracture zones, or oceanic core complexes), the ubiquitous presence of MORB provides us with a key to understanding global geochemical variations of the Earth's interior in relation to plate tectonics. In fact, MORB has been considered to show a homogeneous chemical composition. In terms of volcanic rocks from other tectonic settings (e.g., island arc, continental crust, ocean island), this simple concept seems to be true. However, recent investigations reveal that even MORB has significant chemical variations that seem to correspond to location (Pacific, Atlantic, and Indian Oceans). These observations suggest that the mantle beneath each ocean has a distinct chemical composition and an internally heterogeneous composition. In this paper, global geochemical variations of MORB in terms of major and trace element compositions and isotope ratios are examined using a recently compiled database. The compilation suggests that MORB has heterogeneous compositions, which seem to originate from a mixture of depleted mantle and some enriched materials. Coupled with trace element compositions and Pb-isotope ratios, there seems to be at least two geochemical and isotopic domain of the upper most mantle: equatorial Atlantic-Pacific Oceans and southern Atlantic-Indian Ocean. Material (melt and/or solid) derived from plume, subducted slab, subcontinental crust, or fluid added beneath an ancient subduction zone is a candidate to explain the enrichment end-member to produce heterogeneous MORB. Because MORB is heterogeneous, using a tectonic discrimination diagram that implicitly subsumes homogeneous MORB or its mantle sources should be reconsidered. Further investigations, particularly of off-axis MORB, are needed to understand the relationship between heterogeneous compositions of MORB and geophysical parameters (e.g., degree of melting, temperature, spreading rate, crustal thickness, etc). In addition, the role of the MOHO transitional zone should be investigated to interpret the chemical characteristics of MORB.

著者

零丁

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.11, no.7, pp.512-514, 1899

著者

鹿園 直建 荒川 貴之 中野 孝教

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.123, no.3, pp.323-342, 2014-06-25 (Released:2014-07-03)

参考文献数

26

被引用文献数

2 6

---

Water samples (number of samples = 52) were collected from the vicinity of the southern foot of Mt. Fuji, central Japan, and were analyzed for major elements (Si, Al, Fe, Mg, Ca, Na, K, Cl-, HCO3-, NO3-, etc.) and other chemical properties (pH, EC, ORP, etc.). The results show that major element concentrations increase with decreasing elevation, particularly at a low-elevation site. In the Yoshihara area, located at the southwestern foot, anion and cation concentrations vary widely and increase from west to east. In this area, water samples with a high total concentration tend to contain a high NO3- concentration, suggesting NO3- pollution of the groundwater. By contrast, in the southeastern area, NO3- pollution was not recognized. Based on nitrogen isotopic and ionic concentration data, the high NO3- concentration in the southwestern area is considered to be due to inorganic fertilizer (e.g. (NH4)2SO4) used at tea farms. Analytical results show two groundwater flows in a high-elevation area along the Urui River and in the direction from a high-elevation site at the southwestern foot toward Susono City, and that they mix together at a low-elevation site. In the southeastern foot area, two groundwater flows derive from a high-elevation site on Mt. Fuji along the Gotenba mudflow and the Mishima lava flow. The latter groundwater mixes with groundwater derived from Ashitaka and the Hakone mountains.

著者

町田 洋 新井 房夫

出版者

公益社団法人 東京地学協会

雑誌

地學雜誌 (ISSN:0022135X)

巻号頁・発行日

vol.88, no.5, pp.313-330, 1979

被引用文献数

53 27

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The eruptions of the Daisen Valcano (35&deg;22'N, 133&deg;33'E) were mainly rhyodacitic and of the paroxysmal type, producing several extensive sheets of tephra. The Kurayoshi pumice (DKP, for short), one of the excellent Late Pleistocene markers arising from the Daisen valcano, is rhyodacitic in composition with abundant hornblende and orthopyroxene crystals and relatively small amount of biotite. Its identification can be made from the above mentioned mineral assemblages as well as from the characteristic refractive index of orthopyroxene (&gamma;=1.703-1.708) and of hornblende (n<SUB>2</SUB> = 1.673-1.682) and the specific crystal habit of orthopyroxene. This pumice-fall deposit occurs on marine and fluvial terraces in the San'in and Hokuriku districts facing the Japan sea and extends eastward beyond the Northern Japan Alps to north Kanto plain as a thinner discontinuous layer. Stratigraphic relation with the dated tephra layers in north Kanto indicates that the pumice was probably deposited between about 47, 000 and 45, 000 years ago. That is, this pumiceous deposit is found at the intermediate horizon between Yunokuchi Pumice (UP, slightly younger than 49, 000 YBP) and Hassaki Pumice (HP, 40, 000-44, 000 YBP) in north Kanto, about 500 km far from the Daisen.<BR>Daisen Kurayoshi Pumice wonld be particularly valuable for establshing chronological framwork as a fundmental time-marker in arears where no suitable markers have yet been documented. Moranic deposit of the Murodo glacial advance at Mt. Tateyama, Northern Japan Alps, is mantled by this marker and overlies the Raicho-dai pumice-fall deposit, products of the earliest stage of volcanic activity of Tateyama III, which is correlated with the Omachi EPm deposit approximately 60, 000 years old. Distribution of these two unreworked tephras indicates that major valley glaciers had nearly disappeared by the times of these initial tephra falls. The glacial advance at Mt. Tateyama, the most extensive of the advances during Last Glacial age, therefore, apparently culminated between about 55, 000 and 50, 000 years ago. On the other hand, a filltop terrace repesented by Uwadan terrace along the River Joganji flowing from Mt. Tateyama, is covered by DKP and is nearly younger than the pyroclastic flow deposit of Tateyama III. Accumulation of the river of Uwadan stage is, therefore, simultaneous and probably associated with the Murodo glacial advance.

著者

矢野 桂司

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.121, no.4, pp.586-600, 2012-08-25 (Released:2012-09-03)

参考文献数

24

---

This paper presents a brief history of geography in the United Kingdom, how it was institutionalized, referring to external impacts on research and teaching. Although geography has a long history in the United Kingdom as an intellectual activity, extending back to the Age of Exploration in the late 16th century, it has only been institutionalized as an academic discipline in universities since the end of the 19th century. Geography was established as a discipline offering an integrated study of complex reciprocal relationships among human societies and physical components of the Earth. By the early 1960s, quantitative and theoretical revolutions were having considerable impacts not only in the United States but also in the United Kingdom. Since then, geography has become a popular subject in elementary and secondary education, as well as higher education, in the UK. Although spatial science expanded rapidly in the 1960s, and continued to do so in the early 1970s, it never became part of the mainstream of human geography. Some fundamental critiques of the positivist approach led to the emergence of humanistic geography and radical geography. The following decades were turbulent for human geography—exciting but confusing—in part because human geographers were busy exploring new ideas. Then, the GIS revolution occurred in the late 1980s in the USA and the UK, which greatly affected geography. Around the same time, as new aspects of social and cultural geography came to be sufficiently established, differences between spatial science and new social and cultural geography became apparent. By the end of the 20th century, geography was firmly established in UK universities. Geography is taught to a large number of students and attracts many applicants to universities. However, changes in funding regimes and school curricula have influenced education and research. One major change in UK geography in the 1990s can be found in its research orientation. Previously, geography was an integrated area of study, based on physical and human geography, and its focus was on how much a university department could cover in terms of disciplines. However, after a new funding regime, called Research Assessment Exercise (RAE), was introduced, all geography departments came to be graded according to the quality of their research. External assessments of both research through the RAE and teaching through QAA have greatly affected how geography is practiced. Although UK geography remains an apparently successful and vibrant intellectual discipline, it might have suffered from fragmentation. Like all disciplines, geography has become fragmented and diversified in recent decades, because of its greater breadth and depth of knowledge. Based not only on substantive but also on epistemological and methodological differences, it is usually divided into physical and human geography. Moreover, human geography can be distinguished by the two major approaches of spatial analysis and social theory. This is because geography has become a community of sub-communities and individual departments, responding to research and teaching assessments. Despite fragmentation, geography in the United Kingdom continues to develop in the university and school systems, and has a substantive international reputation for the quality of its scholarship.

著者

守田 康太郎

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.73, no.6, pp.377-384, 1964-12-30 (Released:2009-11-12)

著者

小野 晃

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.92, no.7, pp.533-541, 1984-01-25 (Released:2009-11-12)

参考文献数

12

著者

新藤 静夫

出版者

公益社団法人 東京地学協会

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.78, no.7, pp.449-470, 1970-01-25 (Released:2009-11-12)

参考文献数

32

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1) 本地域の地下地質層序は下位より三浦層群下部, 同上部, 東京層群下部, 同中部, 同上部, 武蔵野礫層以上であつて, それぞれの関係は深井戸資料, 電気検層資料, その他によつてかなり正確に識別できる。またこれらは周辺地域における従来の知見ともほぼ一致する。2) 本地域における三浦層群は大きく北東に向かつて緩傾斜をなす向斜状の撓曲構造を示し, 関東造盆地運動の性格をよくあらわしている。そしてこの向斜構造に伴つて大構造の傾斜方向を軸とする顕著な波状構造がみとめられる。3) 以上の地質構造を形成した地殻変動は本層群の堆積中から継続的に行なわれていたと解される。4) 三浦層群の上面には旧河道に相当すると考えられる北東方向の谷地形が形成されている。東京層群下部層はこの凹地を埋積して分布している。なおここにみる地下谷の延長を周辺の丘陵地域にのばすと, 現河川で一致するものが多く, その原型の形成が古いものであることが推察される。5) 上記の地層群を覆つて扇状地性の堆積物と考えられる礫質の地層が広く分布している。これが東京層群中部層であつて, 本層の下底部にも北東方向の顕著な谷地形がみとめられる。6) 三浦層群の上面と東京層群下部層の上面にみとめられる谷地形がともに三浦層群の構造とよく一致している事実から, 三浦層群の地質構造を支配した造構造運動は継続してそののちの地形の形成に影響をおよぼして来たことが推察される。7) 上記の地層の上位に東京層群上部層が重なつている。この地層はかっては, 武蔵野台地の全域を覆つていたと考えられるが, 現在ではその大部分が浸食によつて欠如していて, その分布が武蔵野台地の東縁部と西端部地域の地下に限られている。周辺の所沢台, 金子台, 日野台等を構成している段丘礫層は本層の延長に相当すると考えられる。8) 東京層群中部層上面の地下谷の分布とこれを埋積する東京層群上部層の層相から, 少くとも武蔵野礫層の堆積以前は当地域の水系は継続的に北東ないし, 東北東方向をとつていたものと考えられる。9) 多摩川が現在のような流路をとるにいたったのは上記の水系を強制的に変えるような運動があつたためである。この地変は武蔵野台地の北西部が南東部に対して相対的に上昇するような地盤の傾動であつたと考えられる。そして武蔵野段丘や立川段丘の形成にはこのような地盤の傾動も関与している可能性がある。10) 武蔵野台地の北西部付近での三浦層群の傾斜, 東京層群下部層および中部層の基底部の傾斜がいずれも他にくらべて異常に大きいというのもこの推定をうらづける資料としてあげることができる。