著者

高橋 正樹

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.103, no.5, pp.447-463, 1994-10-25 (Released:2009-11-12)

参考文献数

55

被引用文献数

2 2

著者

神品 芳孝

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.132, no.3, pp.197-216, 2023-06-25 (Released:2023-07-07)

参考文献数

29

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Farming families on the plains of Japan arrange small forest-like woodlands in their farmyards and villages; these woodlands are called “Yashikirin.” While Yashikirin have various functions, geographers are interested in their windbreak function, and have conducted many studies. In recent Yashikirin studies, researchers consider Yashikirin conservation and report that woodland use affects sustainability. On the other hand, recent research on normal forests analyzes forest ownership with the goal of sustainable maintenance. However, in the case of agglomerated settlements, these man-made woodlands can be regarded as normal forests because they are dense and cover relatively large areas. Area variations and ownership of woodlands are investigated with aerial photography, cadaster, and interviews referring to agglomerated settlements in northern Saitama, which experience strong, cold, and dry winds in winter. Combined with meteorological data, the sustainability of these woodlands and their effects on micro-climates are clarified. In some cases, the owner of a woodland at the northern edge of a village does not reside next to it, but in a remote area within the village. In such cases, it becomes difficult for the owner to manage the woodland; as a result, the woodland tends to decline. These woodlands function as windbreaks to protect the entire village from strong winds. Yashikirin have various purposes, but due to socioeconomic changes, they are only used as windbreaks or boundaries between neighboring houses.

著者

永田 玲奈 三上 岳彦

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.132, no.3, pp.257-263, 2023-06-25 (Released:2023-07-07)

参考文献数

9

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An attitude survey is conducted on students taking the Earth Science course at Nihon University College of Law. The survey analyzes factors that encourage students in the humanities and social sciences to take the Earth Science course. Data are collected in the first semester of 2021 through a web-based survey via Google Forms, with a total of 689 respondents. The course's themes are meteorology and climatology. The results reveal that students who took Geography B in high school showed a great interest in natural disasters, while students who took Geography B and Geoscience in high school showed a strong interest in global warming. It was also revealed that students in the humanities and social sciences emphasize knowledge acquisition over comprehension in science courses. This suggests that in order to encourage liberal arts students to take science courses, it is necessary to include in the course contents both knowledge that is useful in daily life and knowledge on disaster prevention. In addition, the syllabus should emphasize that this knowledge can be acquired by taking the course.

著者

岡 義記 寒川 旭

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.90, no.6, pp.393-409, 1981-12-25 (Released:2009-11-12)

参考文献数

18

被引用文献数

1 4

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Geographic Outline AWaji Island lies from NE to SW, dividing the east Inland Sea. The central range running in same direction continues to the Rokko mountains which are thought to have been elevated by crustal movement in Pleistocene (Rokko Movement). In the southern part of this island is the Yuzuruha mountains of Cretaceus sedimentary rocks which are a part of the series of mountain ranges on the north of Median Tectonic Line (MTL). In the plains of this island are seen hills of Pliocene deposits (the Awaji group) elevated from below the bottom of the Inland Sea.Purpose of Study The authors intended in this study to make clear the process of the formation of the east Inland Sea and Awaji Island. In order, they carried out the investigation on following points : 1. Relation between the Miocene deposits and the age of the formation of the erosion surface on the mountains in the north.2. Sedimentary process of the Awaji group.3. Faults and deformation of the Awaji group.Result of study The results obtained are as follows : 1. The morphology of the basement rocks (granitic rocks) in the north had been already gentle and undulating before the Kobe group deposited, caused by the Miocene transgression. The thickness of it reached a few hundreds meter in the north, but after regression the Kobe group was erosed down to basement. The mountains in the north were flattened again in this age.2. In Pliocene time, the area of the east Inland Sea depressed and deposited the Awaji group of gravel, sand, lacustrine silt and clay. In early stage, the lake began to be supplied with sand, and gravel from the area to the north of the island. In last stage, rivers originated to the south of MTL carried gravel (Goshiki-hama gravel) over MTL. to the lake.3. Goshikihama gravel is supposed to be contemporaneous with the Uchihata gravel, which is the lowest of the Osaka group (Yoshiki OKA 1978). The lower part of the Awaji group is suggested to be older than the Osaka group.4. The thickness of the Awaji group reaches 800 meter in the north and 300 meter or more in the middle part of the island. It indicates the depression of the Inland sea in Pliocene time.5. The fault movement in this island took place after the sedimentation of the Awaji group. Reverse and transcurrent faults by E-W compression have been discriminative since the middle of Pleistocene age.6. The faults can be divided, by strike, into three types, as follows : Type I (N60°E) The faults of this type caused the uplift of the Yuzuruha mountains in the south.Type II (N-SNE-SW) This type of faults caused the uplift of the central range of the island.Type III (N20°W) This type of faults are active reverse faults cut through the main range of the island.

著者

松井 圭介 卯田 卓矢

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.6, pp.895-915, 2015-12-25 (Released:2016-01-27)

参考文献数

40

被引用文献数

2 4

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This paper examines the relation between traditional pilgrimages to Mt. Fuji and related tourism in the pre-modern era. It takes into account the worship of Mt. Fuji as a sacred mountain and the activities of oshi pilgrim masters (low-ranking Shinto priests) who organized pilgrimages. Chapter II presents an overview of the worship of Mt. Fuji in its original form before modern times, and the historical development of that worship. Like other sacred mountains in Japan, Fuji was worshiped from a distance as a kannabi, a place where gods were believed to be enshrined. It was also worshiped as an area of the underworld, takai, where ancestral spirits rested. In addition, the mountain was thought itself to be a god: both a benevolent god who brings water and an angry god who brings natural disasters through volcanic eruptions. Historically, pilgrimages by ascetics to Mt. Fuji are first found in sources from the Heian era to the Kamakura era. Subsequently, Mt. Fuji gradually became one of the mountains of Shugendo, a Japanese ascetic-shamanist belief system incorporating Shinto and Buddhist concepts. Chapter III examines the establishment of devotional Fuji confraternities, called Fuji-ko, and the popularization of pilgrimages in modern times. The viewpoints of the various types of Fuji-ko, their religious beliefs, and aspects of their pilgrimages are discussed. In general, a Fuji-ko confraternity consisted of three officers—komoto (host of the ko), a sendatsu (guide), and sewanin (manager)—and members. They made pilgrimages in a three-to-ten-year cycle; the journey was usually a round trip of eight days and seven nights from Edo (the former name of Tokyo) to the mountain, arranged by oshi at Kamiyoshida, at the mountain's foot. Although Fuji was the main destination, others were often included. Some of these were sacred places related to Kakugyo (the founder of the pilgrimage to Mt. Fuji) and Jikigyo Miroku (the famous leader of Fujiko in the Edo era), and other sacred mountains such as Mt. Ooyama. Chapter IV examines the characteristics of Kamiyoshida, the village of oshi priests, which provided pilgrims with a range of services, including accommodation and assistance in climbing the mountain. Kamiyoshida was a particularly large settlement among those at the foot of Mt. Fuji, featuring large residences and rectangular zoning with special entrance roads. At its peak, the village had more than 100 houses aligned in a row. It was very prosperous in summer, when pilgrimages were most frequent. Chapter V examines characteristics of the pilgrimage destination and politics of location. The fact that citizens of Edo could view Mt. Fuji even though it was far away gave it a disarming allure and familiarity. Climbing the mountain was regarded as a great accomplishment, and in this way the pilgrimage became a journey of faith. The oshi priests, as the receiving party, created various legends of faith to draw pilgrims to their village rather than other starting points to Mt. Fuji or other shrines or temples. These legends contributed to the rise of Kamiyoshida and the oshi, and ultimately to their downfall.

著者

関谷 溥

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.79, no.3, pp.175-180, 1970-06-25 (Released:2009-11-12)

参考文献数

7

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September 1, 1923, southern Kanto was devastated by a severe earthquake. The main shock of the events, which occurred at 11 h 58 m (JST), was felt all over Japan. The highest seismic intensity is 7 in JMA scale at the southern part of Kanagawa, Tokyo and Chiba prefectures. The epicenter is located on the Sagami-nada. Parameters of the main shock given by the Japan Meteorological Agency are as follows ;origin time : 11 h 58 m, September 1, 1923.epicenter : 35° 20' N, 139° 20' Emagnitude : 7.9The earthquake was accompanied by many fore- and after-shocks. The foreshocks occurred in Kashima-nada. It seems that the foreshock activities began in May 1923 and became vigorous in June 1923 before the occurrence of the main shock.The aftershocks occurred in Kanagawa, Yamanashi, Saitama, Chiba, Ibaraki prefectures and near seas, and the general trend in decrease of daily number of the aftershocks can be explained by Omori's generalized formula.

著者

小林 貞一

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.98, no.1, pp.34-48, 1989-02-25 (Released:2009-11-12)

参考文献数

43

被引用文献数

1 2

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In Japan 14 species in 21 genera of Carboniferous trilobites were known in 1980 and 22 species in 11 genera of the Permian ones in 1984. Adding a few species described since then, the Permo-Carboniferous trilobites of Japan total about 70 species at present. They are described from 18 horizons, namely 11 and 7 horizons respectively for the Carboniferous and Permian ones. They are compared with the faunas of the Mongolian geosyncline, Hwangho and Yangtze basins and Southeast Asia. While the Mongolian sea retreated from the west side through the periods, the route of migration was maintained toward the Mediterranean sea through the Himalayan geosyncline until the end of the Palaeozoic era. Some trilobites of Japan reveal relationship further toward the Australian and North American sides.

著者

磯崎 行雄 丸山 茂徳 柳井 修一

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.119, no.2, pp.378-391, 2010-04-25 (Released:2010-07-06)

参考文献数

72

被引用文献数

11 9

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A new historical review is presented on the progress of the geological sciences in Japan since the Meiji revolution in 1868. Geological knowledge, particularly studies of the geotectonic evolution and orogenic aspects, of the Japanese Islands has progressed through three distinct phases; (1) non-science stage, (2) colonial science stage, and (3) independent science stage, as modeled by Basalla (1967), who demonstrated a general pattern of transplanting cutting-edge scientific/technological knowledge from western Europe to the rest of the world. During the “non-science” stage from the 1860s to the 1890s, major geological aspects of the Japanese Islands, together with discoveries of unusual rocks, fossils etc., were initially described by foreign geologists (e.g. E. Naumann). In contrast, almost nothing was contributed by domestic geologists. During the “colonial science” stage, from the 1900s to the 1980s, research and education systems were transplanted effectively from western European countries. For example, applying the purely imported concept of geosyncline, the geotectonic history of the Japanese Islands was summarized for the first time by domestic geologists (e.g., Kobayashi, 1941; Minato et al., 1965 etc.). The almost unidirectional acceptance of plate tectonics also followed at this stage, with the exception of the rare but outstanding contribution of A. Miyashiro during the 1960s-1970s. During the “independent science” stage from the 1980s, various new ideas and original techniques in geology were proposed by Japanese geologists with lesser help from the western countries than before; i.e., practical criteria for identifying ancient accretionary complex, exhumation tectonic of ultrahigh to high-P/T metamorphic rocks, and subhorizontal growth framework of subduction-related orogens. Furthermore, in the first decade of the 21st century, the geological science in Japan entered stage of (4), “exporting science” with the introduction of new paradigms, such as the application of detrital zircon chronology to subduction-related orogens, which efficiently recognizes new geotectonic subdivisions and allows paleogeographical reconstruction with much higher resolution than before. These new paradigms (ideas, techniques) from Japan are now on sale for applying to the rest of the world.

著者

小原 一成

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.114-132, 2007-02-25 (Released:2009-11-12)

参考文献数

60

被引用文献数

3 2

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Water affects many geological and geophysical phenomena, for example, earthquake generation. Recently, anomalous earthquakes, which are strongly related to fluid have been detected in a subduction zone by densely distributed geodetic and seismic observation networks. These are called slow earthquakes and are divided into many categories of earthquakes. The long-term slow slip in Tokai or Bungo Channel, which occurs at the subducting plate interface, is a phenomenon with a very long time-constant ranging from months to years. At the deeper part of the long-term slow slip, the short-term slow slip occurs with a period of several days associated with the non-volcanic deep low-frequency tremor in the transition zone on the plate interface in southwest Japan. These slow earthquakes might be related to fluid liberated from the down-going slab by dehydration process. At the shallower part of the subducting plate interface, the very low-frequency earthquakes occur in the accretionary prism near the Nankai trough. These slow earthquakes indicate a weakening of frictional strength at the plate interface and low stress drop due to the existence of fluid.

著者

佐藤 友彦 吉屋 一美 丸山 茂徳

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.128, no.4, pp.571-596, 2019-08-25 (Released:2019-09-20)

参考文献数

109

被引用文献数

11 11

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Phylogenetic analysis is one of the useful tools available for revealing the evolution of life on the Earth; however, it has difficulty in principle distinguishing old and new genomes just by comparing phylogenomic trees. To overcome this difficulty, a new method is introduced which utilizes the Earth's history derived from geologic information to trace genomic evolution. This idea is inspired by Darwin's natural selection, and explains how living organisms change with the environment. In other words, life's genome does not change if the environment remains the same. A key is the birthplace of life on Hadean Earth, which is thought to be an ultra-reducing environment with H2 produced in abundance through serpentinization. OD1 is a potential microbe that has survived on the Earth since the Hadean. Its habitat, Hakuba-Happo in Japan, is a unique serpentinite-hosted hydrothermal system on land, and it has avoided evolution by remaining in a super-reducing environment from the Hadean to the present. OD1 is regarded as a “living fossil” of the Hadean microbe. Ultra-reducing environments have disappeared over the Earth's history. How has OD1 survived since the Hadean to the present? A possible scenario is proposed based on Plate Tectonics. OD1 habitats have gone through the following transitions: (1) super-reducing environment in a natural nuclear geyser on a primordial continent in the Hadean; (2) serpentinite-hosted hydrothermal system along a mid-oceanic ridge transform fault during the Archean-Proterozoic; (3) subduction-accretion and escape from oxygenated Phanerozoic ocean floor; and, (4) jacked up by growth of accretionary complexes and taking refuge in a hydrothermal system above a volcanic front. OD1 habitats have been reduced with geological age as free oxygen has increased in the surface environment. OD1 may be a “living microfossil” of the Hadean, making its way continuously through ultra-reducing environments on a tightrope.

著者

田村 芳彦

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.112, no.5, pp.781-793, 2003-10-25 (Released:2009-11-12)

参考文献数

25

被引用文献数

1 1

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Mantle melting and production of magmas in NE Japan may be controlled by locally developed hot regions within the mantle wedge that form inclined, 50 km-wide fingers. In this case, are these hot fingers chemically and/or isotopically different from the host mantle wedge? Forty-four Quaternary volcanoes in NE Japan have been reviewed to evaluate twodimensional strontium isotopic variations, and to infer 87Sr/86Sr contours of the source mantle. The isotopic composition of magma source materials at depth is found to have little relationship with slab depth, suggesting that mantle heterogeneity was established before the flux of fluid released from the subducting slab reached the magma source regions. On the other hand, Miocene Japan Sea back-arc Yamato basin basalts have the same isotopic variation as the Quaternary volcanic arc. Cousens et al. (1994) suggested the possibility that partial melts of sediments, forming at a depth of >200 km may mix with mantle wedge material (87Sr/86Sr0.703), resulting in a magma source component with enriched 87Sr/86Sr of0.705. I suggest that after the cessation of Yamato basin rifting, a MORB-like mantle source (87Sr/86Sr0.703) in the mantle wedge below the Quaternary NE Japan arc was replenished by a fertile mantle material (87Sr/86Sr0.705) through convection induced by the subducting lithosphere. On its way to the shallower mantle wedge (<150 km), the fertile mantle material changes shape from a hot sheet to hot fingers, for reasons not yet fully understood. Thus, the hot fingers, with 87Sr/86Sr of0.705, extend from150 km below the back-arc region towards the shallower mantle (50 km) beneath the volcanic front. A conveyor-like return flow is interpreted to carry the remnants of these fingers to depth, resulting in greater amounts of fertile material being incorporated in diapirs beneath the volcanic front, and smaller amounts incorporated in areas behind the front.

著者

浜田 信生

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.110, no.2, pp.132-144, 2001-04-25 (Released:2009-11-12)

参考文献数

20

被引用文献数

5 4

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Based on macro seismic and instrumental observation data covering a period of over hundred years, the characteristics of seismic activity around Miyakejima, Kozushima, and Niijima, the northern Izu islands, were investigated. Seismic activity is distributed along the Zenisu ridge and the Nishi-Shitito ridge to the west and along Niijima, Miyakejima, Mikurajima and Hachijojima islands to the east. Most of the seismic activity in the region is of the swarm type and is often induced by a large earthquake or magmatic activity at Miyakejima and other volcanoes. Comparison of macro-seismic data of large earthquakes in the late 1800s and the early 1900s with a seismic intensity map of recent earthquakes suggested that the maximum size of an earthquake in the region is around a magnitude of 6.5 on the JMA magnitude scale. Linear arrangements of seismicity in the NE-SW direction, which is parallel with the Zenisu ridge, and in the NW-SE direction, which is almost normal to the former and parallel to the direction of the plate motion of the Philippine Sea plate, are often recognized. While the strike slip-type earthquake with a NE-SW tension axis is predominant in the region along Niijima, Miyakejima, Mikurajima, and Hachijojima islands, a strike slip with E-W tension axis is predominant in the region along the Zenisu ridge and the Nishi-Shitito ridge. A complex tectonic setting of the region, back arc spreading, collision of the Philippine Sea plate to the Eurasian plate around the Izu peninsula, deformation of the plate due to the subduction of slab from the Suruga and the Sagami trough, must shape the characteristics of seismic activity in the region such as the upper limit of earthquake scale, swarm-type activity, close relation with volcanic activity, and regional stress pattern.

著者

藏田 延男

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.60, no.4, pp.183-190, 1951-12-30 (Released:2009-11-12)

参考文献数

13

被引用文献数

1

著者

都城 秋穂

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.99, no.3, pp.217-229, 1990-06-25 (Released:2009-11-12)

参考文献数

10

被引用文献数

1 1

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The chemical compositions of solid-solution minerals in metamorphic rocks are controlled by equilibria not only of exchange reactions but also of net-transfer reactions among coexisting minerals. In rocks with a variance of 2, the compositions of solid-solution minerals are functions of temperature and pressure alone as is illustrated in Figs. 2 and 3, and so can be used as a measure of the P-T condition under which the rocks were recrystallized. In rocks with a variance of 3 or greater, on the other hand, the compositions of solid-solution minerals vary not only with temperature and pressure but also with the bulk-rock composition (Fig. 4). The growth of zoned crystals causes fractional crystallization, resulting in a change of composition of the reacting system. If the variance of the system is 3 or greater, the change of the composition of the reacting system causes a change in the composition of the crystallizing mineral.Pelitic metamorphic rocks are commonly simplified as belonging to the 6-component system : Al2O3-FeO-MgO-K2O-SiO2-H2O. In this case the mineral assemblages may be shown on the THOMPSON AFM diagram. Any 3-AFM phase assemblage in the diagram has a variance of 2, whereas any 2-AFM phase assemblage has a variance of 3.In the paragenetic relations of garnet, MnO commonly plays an essential role, and so garnet-bearing metapelites are commonly treated as belonging to the 7-component system : Al2O3-FeO-MgO-MnO-K2O-SiO2-H2O. Most metapelites with MnO-rich garnet have a variance of 3 or greater. Garnets in low- and middle-grade metamorphic rocks are usually strongly zoned. Hence, the composition (or the MnO content) of garnet is strongly influenced by the initial bulk-rock composition and fractional crystallization. SPEAR (1988) has calculated the progressive compositional change of garnet that grows not only under complete equilibrium condition but also with fractional crystallization for garnet-bearing 3-AFM phase assemblages that are observed in the Barrovian sequence.In the Sanbagawa high P/T ratio metamorphic belt, progressive metamorphism is represented by a sequence of the chlorite zone, garnet zone (with no biotite), and biotite zone (with garnet) for metapelites. In other words, garnet begins to occur at a considerably lower temperature than biotite. In the garnet zone, garnet probably forms by reaction involving Tschermak exchange component like (4), whereas in the biotite zone, garnet forms by the same reactions as in the garnet zone of the Barrovian sequence. Such a change in the garnet-producing reactions between the two zones may cause a break in the MnO and FeO curves in the composition profile of zoned garnets. Some of the observed features of the compositional trends of garnets could be ascribed to the effect of a variation in bulk-rock composition.The average composition of zoned garnets in metapelite shows a progressive decrease of the MnO content with increasing metamorphic grade. This is probably related mainly to a progressive increase of the amount of garnet. Higher pressure tends to increase the amount of garnet, and to decrease its MnO content.

著者

山田 直利 矢島 道子

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.4, pp.692-704, 2011-08-25 (Released:2011-11-10)

参考文献数

21

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Edmund Naumann (1854–1927) came from Germany and stayed in Japan for ten years from 1875. He performed a lot of pioneering research on the geology and geography of Japan, which were written mostly in German and recently translated into Japanese by N. Yamashita (1996). However, a paper titled “Skizze der Orographie von Japan” published in 1893 on “Petermanns Geographische Mitteilungen” as the third article of Naumann's “Neue Beiträge zur Geologie und Geographie Japans” has not yet been translated. The paper, which we have now translated into Japanese as “Nihon Sangaku Shi Taiyo”, consists of two parts. The first part deals with the relationship between the topography of mountainous lands and geology, in terms of volcanoes, old mountainlands, granitic mountains, coastlines, depressions, longitudinal and transverse valleys, watersheds, etc. The second part deals with the topographic character of each geotectonic zone of Japan: the northern and the southern wings of the Japan Arc and the Fossa Magna intervening between both wings. One figure and one table are included in this paper. Fig. 1 is an altitude layer map of the main three islands of Japan with a scale of 1:2,600,000, the earliest one drawn with contour lines. Table 1 is a list of the main mountaintops of Japan (eighty-seven mountains), including location, altitude, and geologic nature. Furthermore, a supplementary figure, which shows the distribution of the main mountaintops, watersheds, and geotectonic divisions of Japan, was made by the translators.

著者

岩橋 純子 安藤 明伸 西岡 芳晴 川畑 大作 白石 喬久

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.131, no.4, pp.463-472, 2022-08-25 (Released:2022-09-08)

参考文献数

19

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A system was created using an exploration-type computer game as the basic material, and its educational effects were verified with the aim of stimulating the interest of students of the digital native generation in the local history of the region. Research classes were conducted using Minecraft (Mojang/Microsoft) teaching materials at Miyagi University of Education Junior High School in Sendai City. The theme of the classes was to convey knowledge about the geology and geological history of the region. Teaching materials were created for students to learn about geological formations in the Kamisugi area of Sendai City, including the region of their junior high school, with the aim of deepening their interest in local geological history and their understanding of the changing earth. A Minecraft world was used with underground strata that reflected information from a geological boring survey conducted in the past at the school, school buildings, and teleportable landscapes of past geological eras, and questions were asked on knowledge of geology based on school textbooks or research papers. The following were confirmed from the research classes at the junior high school. The game using a familiar school as a setting was very popular among the students, and they were not bored by the knowledge questions. The key words of the geological era that the students reached were frequently mentioned in the questionnaire given after the classes. The game is considered to be effective for helping students to understand and remember things visually, while having an enjoyable and positive experience.

著者

苅谷 愛彦 原山 智 松四 雄騎 清水 勇介 松崎 浩之

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.131, no.4, pp.447-462, 2022-08-25 (Released:2022-09-08)

参考文献数

59

被引用文献数

1

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The geomorphological and geological characteristics, distributions, and ages of block slopes that developed at two alluvial cones (Bentenzawa valley and Okumatazirodani valley) along the Azusa River in the Kamikochi area, northern Japanese Alps, are clarified. These block slopes were believed to be of Pleistocene glacial origin in previous studies. A field survey was conducted, applying microtremor array observations to estimate subsurface geology, and in situ terrestrial cosmogenic nuclide (TCN) dating to estimate age of occurrence. At the Bentenzawa alluvial cone, the block slope is composed of large blocks and lithic fragments originating from heterogeneous igneous rocks, mainly of welded tuff and granophyre, that do not exist in the Bentenzawa valley watershed. Large blocks and lithic fragments of the block slope show clast-supported facies accompanied by jigsaw-crack fracture structures without a fine matrix. A mass of rock blocks fell from a steep wall of igneous rocks around the head of the Okumatajirodani valley, at approximately 2280 to 3090 m a.s.l., on the opposite side of the Bentenzawa valley. Rock slope failure and runout debris flow of blocks are thought to be the principal motions behind the mass movement from the rockwall. Block behavior comprised 3 km horizontal and 1.5 km vertical movements. Blocks were finally transported to the alluvial cone of the Bentenzawa valley to form an opposing impact slope. The results of microtremor array observations suggest that materials of rock blocks about 20 m thick spread and were buried beneath the present riverbed of the Azusa River. The estimated volume of landslide materials is more than 1.1 × 107 m3; age is estimated to be 6900 ± 1000 yrs BP. The Bentennzawa block slope is not of glacial origin. The block slope at the Okumatajirodani alluvial cone consists of large lithic fragments of igneous rocks distributed in this watershed. A mass of rock blocks was supplied by slope failure or debris flow in the Okumatajirodani valley, and was transported and emplaced on the alluvial cone. The volume of the failure is estimated to exceed 2.9 × 105 m3 and its age is estimated to be 900 ± 100 yrs BP.

著者

吉屋 一美 佐藤 友彦 大森 聡一 丸山 茂徳

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.128, no.4, pp.625-647, 2019-08-25 (Released:2019-09-20)

参考文献数

77

被引用文献数

4 4

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The Hadean surface was mainly covered by three kinds of rock: komatiite, KREEP basalt, and anorthosite, which were remarkably different from those on the modern Earth. Water–rock interactions between these rocks and water provided a highly reducing environment and formed secondary minerals on the rock surface that are important for producing metallo-enzymes for the emergence of primordial life. Previous studies suggest a correlation with active sites of metallo-enzymes and sulfide minerals based on an affinity with their structure, but they do not discuss the origins of metallic elements contained in these minerals, which are critical to understand where primordial life was born. Secondary minerals formed through water–rock interactions of komatiite in a nuclear geyser system are investigated, followed by a discussion of the relationship between active sites of metallo-enzymes and secondary minerals. Instead of komatiite, we used serpentinite collected from Hakuba Happo area, Nagano Prefecture in central-north Japan, which is thought to be one of the Hadean modern analogues for the birthplace of life. Several minor minerals were found, including magnetite, chromite, pyrite, and pentlandite, in addition to the major serpentine minerals. Pentlandite is not been mentioned in previous studies as a candidate for supplying important metallic elements to form metallo-enzymes in previous studies. It also acts as a catalyst for hydrogen generation, because it closely resembles the structural features of an active site of hydrogenases. Nickel-iron sulfide, pentlandite, is considered to be one of the important minerals for the origin of life. In addition, what kinds of minor mineral would be obtained from water–rock interactions of these rocks is estimated using a thermo-dynamic calculation. KREEP basalt contains large amounts of iron, and it could be useful for producing metallo-enzymes, especially for ferredoxins, an electron transfer enzymes associated with the emergence of primordial life.

著者

奥山 育子

出版者

Tokyo Geographical Society

雑誌

地学雑誌 (ISSN:0022135X)

巻号頁・発行日

vol.95, no.1, pp.46-61, 1986-02-25 (Released:2009-11-12)

参考文献数

19

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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.

著者

香月 興太 瀬戸 浩二 菅沼 悠介 Dong Yoon YANG

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.128, no.3, pp.359-376, 2019-06-25 (Released:2019-07-11)

参考文献数

22

被引用文献数

3 5

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A suitable sampling tool is indispensable for making sediment observation. Eleven portable sediment core samplers using lake sediment observations are introduced: two box core samplers, four dropping core samplers, and five pushing core samplers. Some are popular for making sediment observations. However, others are unique and are not well known, although they have excellent characteristics. Their structures, merits, demerits, and suitable lake conditions are explained. Core samplers introduced are: Ekman-Birge grab sampler, Smith-McIntyre grab sampler, Rigo gravity corer, Limnos corer, Knocking corer, Mackereth piston corer, Proto-type pushing piston corer, Seto-type undisturbed separable piston corer, Suganuma-type portable percussion piston corer, Multisampler, and Russian Peat sampler.