著者

河村 善也

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.31, no.1, pp.1-12, 1992

被引用文献数

3 5

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帝釈峡遺跡群に属する観音堂, 堂面, 穴神, 馬渡の4遺跡から産出した哺乳動物化石の層序学的な分布を, 現在までに得られた資料をもとにまとめた. これらの遺跡から産出した哺乳類の約69%は現在もこの地域に生息する種類で, その大部分は後期更新世の後半から連続してこの地域に生息していたものと考えられる. 一方, 全体の約19%は現在この地域には分布しないが, 他の地域には生息している種類で, これらは後期更新世から完新世にかけてのいろいろな時期に, この地域から絶滅したと考えられる. 残りの12%は絶滅種で, それらはすべて後期更新世末までに絶滅したと考えられる. 現在この地域に分布しない種類や絶滅種のこの遺跡群における消滅層準の年代は, 32,000から21,000年BPの間 (ヒョウ), 21,000から16,000年BPの間 (ニホンモグラジネズミ, ヒグマ属, ゾウ科の動物), 16,000から12,000年BPの間 (ニホンムカシハタネズミ, ブランティオイデスハタネズミ), 10,000年BP頃 (ヤベオオツノシカ), 6,000から5,000年BP頃 (オオヤマネコ) で, これらの年代は各種類の本州におけるおおよその絶滅時期と対応する可能性が高い.

著者

堤 隆

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.42, no.3, pp.205-218, 2003-06-01

参考文献数

57

被引用文献数

1

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日本の後期旧石器時代は,未較正の¹⁴C年代で3.3万年前から1.3万年前のおよそ2万年間存続し,時期的にはAT降灰期前後を境に前半と後半に区分される.本稿では,前半期を前葉と後葉に,後半期を前葉・中葉・末葉に区分し,各時期の石器群の様相について,特に寒冷気候への適応に注目して概観した.前半期前葉は局部磨製石斧と台形様石器に,前半期後葉は石刃技法の成立やナイフ形石器の登場に,後半期前葉は石器群の地域性の発現に,後半期中葉は尖頭器石器群などの地域的展開に,後半期末葉は列島全域におよぶ細石刃石器群の展開によって特色づけられる.<br>後期旧石器時代前半期前葉に登場する掻器と呼ばれる石器は,後期旧石器時代の諸石器群にあまねく伴う石器ではなく,時空的な偏りをもって保有される石器である.とくに掻器は高緯度地域に濃密に分布する傾向があり,使用痕分析から導き出される皮なめしという機能推定とあいまって,防寒のための毛皮革製品製作用具であることがうかがえ,寒冷環境への適応を物語る石器として重要視される.<br>後期旧石器時代の編年を地域ごとにいかに精緻に組み立て,同位体ステージで示されるような環境イベントとの対応関係をどのように読み取るかは,後期旧石器時代研究の今日的な課題のひとつである.掻器の存在は,最終氷期最寒冷期のより寒冷な環境への人類の適応戦略の解読を可能としている.

著者

早川 由紀夫 由井 将雄

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.28, no.1, pp.1-17, 1989

被引用文献数

5 23

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The eruptive history of the Kusatsu Shirane volcano is well described by means of 14 beds of key tephra and intercalating loess soil. Three eruptive stages are recognized. During early or middle Pleistocene the Matsuozawa volcano was formed; this is the first stage. The second stage was initiated by effusion of the Horaguchi lava, which was followed by eruptions of the Oshi pyroclastic flow, older lava flows, 3P pumice fall, and Yazawahara pyroclastic flow. Brown loess soil about 10m thick covering these deposits indicates that a dormant period of more than 100, 000 years followed this stage. The summit area upheaved about 400m or more against the foot of the volcano during this period, as is suggested by the extraordinarily steep (6.1°-3.0°) surface of the Oshi ignimbrite plateau. The third stage, which started about 14, 000 years ago, is the formation of three pyroclastic cones on the summit and contemporaneous effusion of the younger lava flows, <i>e. g.</i> the Kagusa lava of 7, 000 years ago and the Sessyo lava of 3, 000 years ago. In historic times, phreatic explosions have frequently occurred on the summit crater, Yugama. This means that the present belongs to the third stage. It is unlikely that eruptions of the third stage are caused by cooling of the magma chamber which was active in the second stage. The activity of the third stage seems to denote arrival of a new magma chamber at shallow depth.

著者

横山 卓雄

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.38, no.4, pp.271-286, 1999-08-01

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A.D.79年のヴェスヴィオ火山噴火による噴出物は2つの基本的な要素に区分できる.ポンペイ降下軽石層,ポンペイ・サージ層の2つである.ポンペイ降下軽石層は主として降下軽石からなり,ポンペイ・サージ層は火砕流堆積物,土石流堆積物,降下火山灰層などを含んでいる.火砕流は,少なくとも6回古代都市ポンペイに来襲した.それらの堆積物をPS-1~PS-6と名付けた.また,2層の土石流堆積物(PD-1とPD-2)がみられる.<br>家の壁を倒したり,壁・瓦などの破片といった家屋材の大きい塊を含んでいたりすることからみて,最も力の強かったのはPD-2土石流堆積物である.PS-3をもたらした火砕流もまた人間の頭蓋骨や,やや大きい木を切っているので強力であった.<br>A.D.79年のヴェスヴィオ火山の活動で噴出したポンペイ降下軽石は30~40分間で降下した.ヴェスヴィオ噴火からの火山噴出物によって,多数の建物や塔は完全に埋没したわけではないこと,噴火直後地表面には人工物の破壊された跡がまだみえる状態で残っていたということが想像される.<br>ヴェスヴィオ噴火の火山活動と火山噴出物の堆積のタイム・テーブルの素案が提唱された.

著者

早田 勉

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.28, no.4, pp.269-282, 1989 (Released:2009-08-21)

参考文献数

42

被引用文献数

10 7

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A very important problem for Quaternary research is determining when human beings first settled the Japanese islands. Recently many artifacts of the Early Paleolithic age, dating from before 30, 000 years ago, have been discovered in the northern part of Sendai plain, North Japan. The age of these artifacts has been determined mainly by radiometric dating methods.On the other hand, tephrochronology is an effective technique for establishing Quaternary stratigraphy in the Japanese islands and their surrounding area. The author investigated the age of horizons bearing artifacts on representative sites of that age from the viewpoint of tephrochronology.The stratigraphy of proximal tephra layers is indicated in Fig. 1. Useful widespread tephra layers for chronological study of this area are Toya (ca. 90, 000-100, 000y.B.P.), On-Pm I (ca. 80, 000y.B.P.), Aso-4 (ca. 70, 000y.B.P.) and AT (ca. 21, 000-22, 000y.B.P.). Toya, On-Pm I, Aso-4 and AT were discovered from the horizons between IcP and KtA, IcP and KtA, N-N and N-Y, and N-Y and NK-U, respectively. At Babadan A site, artifacts of the Early Paleolithic age were excavated from horizons in Ando soil found below IwP, just below and above IcP, between IcP and KtA, just above N-Y, and between N-Y and NK-U. Consequently, the artifacts excavated from the horizons below KtA belong to the Early Paleolithic age. At Zazaragi site, another representative site belonging to the Early Paleolithic age, the artifacts were excavated from the horizons of orange-colored volcanic ash (the lower part of Yasuzawa volcanic ash). During the excavation, this deposit was regarded as an airfall tephra layer. But the author interpreted this deposit as a weathered part of a pyroclastic flow deposit (N-Y3) on the basis of the following observations:(1) The boundary of the lower part of Yasuzawa volcanic ash and lower pyroclastic flow deposit is irregular and not clear in some place.(2) It is massive and not layered. There is no intercalation of soil.(3) It is not well sorted.(4) It includes charcoals.(5) It has segregation pipes. Some of them develop at the boundary of the lower part between the Yasuzawa volcanic ash and the lower pyroclastic flow deposit.The author believes that the artifacts were incorporated into pyroclastic flow and carried to their present site.The horizons from which artifacts of the Early Paleolithic age in Japan have been excavated are plotted in Fig. 8. It has been confirmed that some widespread tephra layers originated from gigantic eruptions and covered the area surrounding the Sea of Japan (cf. MACHIDA and ARAI, 1933). The author believes that common chronological studies of Paleolithics in this area are made feasible by tephrochronology.

著者

亀井 節夫

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.29, no.3, pp.163-172, 1990-08-20 (Released:2009-08-21)

参考文献数

36

被引用文献数

5 5

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This is a summary of the presidential address to the public at the 19th annual meeting of the Japanese Association for Quaternary Research, held at Tottori August 18-20, 1989. The address had two parts: one was an introduction to the concept of “Quaternary” and the significance of Quaternary research, and the other was an elucidation of the discussion at the symposium on “Paleogeography and Paleoenvironments around the coastal areas of the Japan Sea”, exemplified by elephant fossils from the sea-bottom of the southern Japan Sea. The pioneers of Quaternary research in Japan, the German geologists E. NAUMANN and D. BRAUNS, were very interested in the elephant fossils of Japan and published papers on them in 1881 and 1883, respectively. Since that time, the study of elephant fossils and Quaternary research in Japan have been closely related.Since about 20 years ago, several elephant tusks and molars have been dredged by dragnet fisheries off the San'in district and also off the Noto peninsula in the southern Japan Sea. They were obtained from depths of 120m to 400m, on either the continental shelf or on the drowned bank of the sea-bottom. Formerly, those materials were considered to verify the presence of a landbridge in the past around the area of the Tsushima strait between Korea and Kyushu, but now this idea has come to be rejected. The results of analysis for the boring cores drilled at several places on the bottom of Japan Sea afford much information about paleoenvironmental changes during the Late Pleistocene. For example, an inflow of the Tsushima warm current to the Japan Sea, which is one of the remarkable tributaries of the Kuroshio, was reduced or arrested at that time by mixing with fresh water from the Hwang Ho River running through North China. This created a stagnant condition in the bottom water of the Japan Sea, and much influenced the biotic community there. Again, the inflow of the Tsushima warm current to the Japan Sea was regenerated beginning about 6, 500 y. B. P.The elephant fossils on the sea-bottom consist of tusks and molars of Naumann's elephant Palaeoloxodon naumanni and a molar tooth of woolly mammoth Mammuthus primigenius. The radiocarbon dating carried out for these and others found on land showed that the former was older than 30, 000 y. B. P. and the latter was younger, around 20, 000 y. B. P. It is known that during the maximal cold phase in the Last Glacial, woolly mammoths came down from Siberia southward to Hokkaido, but did not cross over the Tsugaru strait to Honshu. Therefore, it is reasonable to assume that the remains of woolly mammoths would be transported by drifting from the Hwang Ho area to that off San'in and then sink to the bottom of the Japan Sea. However, the idea is still a matter of imagination, more investigation for the environmental changes during the Quaternary in Japan needs to be done.

著者

藤木 利之 酒井 恵祐 奥野 充

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

pp.62.2202, (Released:2023-09-16)

参考文献数

43

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クック諸島アチウ島Areora地区東部の湿地から得られた堆積物で花粉分析を行った結果,約1,600 cal BP (約350 cal CE) にココヤシと草本の花粉,シダ胞子,木炭片が急増し,タコノキ属花粉やヘゴ科胞子が急減するという劇的な植生変化が確認された.大規模な森林伐採などによるかく乱により,草原が拡大したと考えられた.アチウ島は約350 cal CEに人類が定住していたと考えられたが,この時代にアチウ島には人類定住の痕跡となる考古学データは全くない.また,約1100 cal CE以降にサツマイモなどの栽培植物花粉が微量ではあるが出現し,木炭片が急増した.よって,アチウ島への人類到達は2段階ある可能性が示された.年代は若干異なるが,この結果はTiroto湖の古環境データとほぼ一致している.堆積物を用いた古環境復元から人類定住年代を研究する場合は,島の様々な集水域の堆積物の分析を行って,多面的な分析結果から議論する必要があると考えられた.

著者

堀口 万吉

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.22, no.3, pp.231-244, 1983-11-30 (Released:2009-08-21)

参考文献数

15

被引用文献数

4 4

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The Juno Peaty Site is situated on the Shibakawa lowland in the eastern part of Omiya City, Saitama Prefecture, and was investigated on the field from 1977 to 1981. The investigation was conducted to examine the natural environment of this site by the cooporation of archaeologist, geologist and many biologists. As the results, archaeological remains were found abundantly and useful observations were carried out, and many samples for scientific analysis were obtained to reconstruct the Juno's natural environment.This paper deals with a summary of the Juno Peaty Site with mainly geological evidences and several points of the problem to reconstruct of natural environment of this site. Especially, height and age of the highest sea level on the Holocene Transgression (Jomon Transgression) and palaeovegetation in the Jomon Age are described.Rising of sea level of Jomon Transgression in this site stagnated temporarily in the Kurohama stage (ca. 5, 700y.B.P.) showh by Kurohama Sand Bed with wave cut platform and trace fossils at 1m height on recent sea level, and thereafter, more risen sea level reached ca. 3m height on recent sea level in Moroiso-a stage. This 3m height indicates a upper limit of marine deposit in the highest sea level stage. Therefore it is presumedthat the highest sea level of Jomon Transgression stay on 3m height or more in the Moroisoa stage (ca. 5, 300y.B.P.) of Early Jomon Age.On the palaeovegetation in Jomon Age it is thought generally that the laurel forest (Cyclobalanopsis) had covered on the Pacific coast of Japan from Early Jomon Age downward. In the site, however, it was found out that the deciduous broad-leaved forest (Lepidobalanus) was dominant during the Jomon Age. This aspect is in contrast with the viewpoint that the laurel forest covered on the area of the Pacific coast in Japan, and it is characteristic feature found over the central part of Kanto Plain.

著者

藤 則雄

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.14, no.4, pp.195-220, 1975-12-31 (Released:2009-08-21)

参考文献数

38

被引用文献数

11 6

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Some coastal sand dunes, such as the Himi, Uchinada, Katayamazu and Sanribama dunes, are distributed widely along the coast of the Japan Sea in the central Japan. I have made for about two decades research of the coastal sand dunes throughout the Japanese Islands, especially the Hokuriku district, from the view points of the age of formation of sand dunes, palaeoenvironment during the time of the formation of sand dunes and the relationship between the age of formation and change of sea-level.In this article I have proved the following six items in regard to the coastal sand dunes of the Hokuriku district:(1) Summary of some gists of the distribution, arrangement, basement and age of formation of the coastal sand dunes.(2) The age of formation of the coastal sand dunes which are distributed in the Hokuriku district is divided into seven periods as follows: First period-the Late Pleistocene Riss/Würm Interglacial age, Hiradoko stage; Second period-the late substage of the Earliest Jomonian age to the early substage of the Early Jomonian age; Third period-the late substage of the Early Jomonian age, the highest sea-level stage of the Flandrian transgression age; Fourth period-the earliest substage of the Middle Jomonian age; Fifth period-the Late Jomonian age to Yayoian age; Sixth period-the early substage of the Tumulusian age, the old tomb age, the Minor transgression age; Seventh period-the middle Muromachi age. Among them, the time when larger dunes were formed is the fourth, fifth and sixth periods.(3) Judging from the view point of relationship between the formation of the coastal sand dunes and the palaeoenvironment in the time of formation, both the palaeotemperature and palaeomoisture during the Holocene epoch were not in direct connection with the formation of the coastal sand dunes.(4) The necessary conditions for the formation of the coastal sand dunes are the following: (a) supply of sand, (b) migration of sand, and (c) sedimentation of sand. The conditions were prescribed by a position of strand line, it needs the fix of the position of the strand line for the formation of the coastal sand dunes.(5) From the view point of relationship between the change of sea-level and the formation of the coastal sand dunes, when the environment was changed topographically by the change of sea-level, a scale of sand dune may be changed by the fact that the above-mentioned three conditions are promoted or hindered under this changed environment. Roughly speaking, better conditions for the formation of sand dune may be just after the time when a sea-level changes from rising to lowering.(6) The relationship between the relative change of sea-level, the change of palaeoenvironment and the formation of the coastal sand dunes in every stage of the Holocene epoch is described in this article in the concrete.

著者

藤 則雄

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.10, no.3, pp.134-146, 1971-10-30 (Released:2009-08-21)

参考文献数

17

被引用文献数

2

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Palynological, stratigraphical and chronological investigations were made on the Holocene buried humus soils intercalated in the coastal sand dunes developed along the Japan Sea in the Hokuriku district, Central Japan.The purpose of the present investigations is to determine a definite age of the formation of the humus soils, palaeoclimatic condition under which they were formed, their topographical environments and the relationship between the formation of their humus soils and coastal sand dune and the cahnge of sea-level.Most of the studied humus soils and peat deposits are considered to have formed during the close of the Middle Jomonian to the Early Old Tomb periods. The conclusion are based on 14C dating, the stratigraphy, topographical setting and archaeological remains found in the humus soils.The palaeoclimatic condition at those periods was cool temperate, judging from such macroplant remains as erect tree stumps, leaves and seeds, and microplants as pollen grains and spores. The annual mean temperature was estimated at some 11°C, and the flora which was developed on the Inner and Middle or Old sand dunes was composed mainly of either a riparian or a mixedslope type, being closely similar to the present lowland vegetation in the northern Honshu.A relative minor rise of the sea-level and migration of the coastal sand dunes seem to have caused the formation of most of the buried humus soils and peat which is called Sotan in Japanese, and submerged and buried forests in the coastal areas of the Japan Sea, Hokuriku district, Central Japan.

著者

岩本 有加

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.44, no.3, pp.145-153, 2005-06-01 (Released:2009-08-21)

参考文献数

24

被引用文献数

1 1

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縄文時代早・前期人の骨形態的特徴のひとつとして,扁平脛骨が知られているが,この特徴はすべての早・前期人に見られるわけではない.今まで扁平脛骨の成因についてはいくつかの要因が提案されているが,生活習慣に深いかかわりをもつ環境要素,つまり遺跡の立地条件からの議論は少ない.本稿では,脛骨の扁平度と環境要素との関連性を明らかにするために,脛骨の中央横断示数と遺跡周辺の起伏量との関連を検討した.その結果,起伏量の小さな遺跡から出土した人骨については,扁平脛骨が見られないことがわかった.それに対し,小起伏丘陵と大起伏丘陵に立地する遺跡から出土した脛骨は,扁平度が強い.なかでも小起伏丘陵に立地する遺跡から出土した脛骨については,強度の扁平脛骨が見られた.したがって,脛骨の形態は遺跡の立地条件と密接な関係があると考えられる.

著者

渡辺 直経

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.9, no.3-4, pp.176-183, 1970-12-31 (Released:2009-08-21)

参考文献数

30

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Early Pleistocene refers to the period from Pre-Günz to either the end of Mindel or the end of Günz glaciation, the latter being rather widely adopted in the field of geology and palaeontology. The most important man-like creatures so far known from the period are Australopithecines which accompany with the Villafranchian fauna in Africa. According to the finds at their living sites, it seems out of question that they had already acquired the bipedal locomotion and reached the level of tool-making.In 1931 Dr. N. Naora discovered a human coxal bone imbedded in an earth lump which he believed to have been dislocated down from the upper Lower or lower Middle Pleistocene deposit at a cliff on the coast of the Inland Sea near Akashi, Hyogo Prefecture. The bone was destroyed by fire in 1945, but a few years later its cast was studied by Dr. K. Hasebe, who found primitive characteristics of the bone and proposed a tentative name Nipponanthropus akashiensis. Besides the bone, Dr. Naora discovered crude stone implements from the layer comparable to that of Nipponanthropus. However, it remains controversial as yet whether the Pleistocene deposit had actually yielded the bone in question.

著者

太田 陽子 海津 正倫 松島 義章

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.29, no.1, pp.31-48, 1990-04-15 (Released:2009-08-21)

参考文献数

124

被引用文献数

56 53

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This paper reviews studies conducted between 1980 and 1988 on relative sea level changes and coastal evolution during the Holocene in Japan. The Japanese Working Group of IGCP Project 200, on “late Quaternary sea level changes, ” compiled the two-volume “Atlas of Sea Level Records in the late Quarternary in Japan” in 1987, which included materials related to this topic, based on papers published since 1980. The group also compiled the “Middle Holocene Shoreline Map of Japan (1:200, 000), which demonstrated the location of the middle Holocene shoreline with numerous data on height and radiocarbon age representing the sea level of that stage, and with 15 insets, considered to be typical examples of various types of study. Numbers of papers by year in terms of research field and study area are summarized in Figs. 1 and 2. Several review papers on sea level study have been also published in the last several years, in addition to local studies.Relative sea level curves published in the past 10 years are shown in Fig. 3. The curve patterns show noticeable local or regional differences, reflecting tectonic factors with a different amount and character in each area. Some areas characterized by a rather late culmination age of the postglacial transgression contrast with most of the Japanese coast, which has a culmination age of ca. 6, 000 to 6, 500y.B.P. Two minor fluctuations of Holocene sea level which were pointed out by OTA et al. (1982), have been recognized in several areas; a eustatic origin for such fluctuation is most likely, judging by the nearly coincident occurrence of climatic fluctuation revealed by pollen analyses, molluscan assemblage analyses and submarine core data.The following topics are discussed in particular detail in this paper: 1) Progress of excavation on the Holocene lowland and coral reefs, in order to obtain systematic samples for identification of marine limits and samples for analyses of various fossils and for dating. 2) Holocene marine terrace study with special reference to coseismic uplift and volcanic activity. 3) Identification of the former sea level on the rocky coast. Barnacles and tube worms (Pomatoleios kraussii) as sea level indicators are discussed, including problems with accuracy of radiocarbon dating. 4) Problems concerning the recognition and accuracy of former shorelines in the large alluvial plain. 5) The significance of small drowned valleys as a suitable field for the reconstruction of sea level change. 6) Climatic fluctuation during the Holocene, with relation to sea level fluctuation. 7) Increased overseas studies on Holocene sea level change by Japanese scientists.

著者

五十嵐 太郎

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.35, no.3, pp.247-252, 1996-07-31 (Released:2009-08-21)

参考文献数

14

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亀田郷は越後平野のほぼ中央に位置し,かつては河川の氾濫による水害常習地帯であり,その大部分が湿地帯であったので,「葦沼」と称されていた.したがって,ここでの水田の開拓と稲作作業は,すべて過酷な水との闘いであった.しかし,大河津分水の開削(1927年),阿賀野川の河川改修工事(1933年)などの治水事業により洪水の被害からのがれ,さらに栗ノ木排水機の新設(1948年)と耕地整理の完了(1956年)により,統一的な地上水の排除が可能となり,ようやく近代農業の基礎が築かれた.ここでは,まず湿地帯すなわち「葦沼」での水田開発と「葦沼水田」の実態,ついで内外の治水対策,とくに内部治水対策,最後に耕地整理(全郷の統一的地上水排除)とこれに伴う稲作技術の対応について述べる.

著者

福田 正己 木下 誠一

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.12, no.4, pp.192-202, 1974-02-28 (Released:2009-08-21)

参考文献数

41

被引用文献数

24 14

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In this paper, the authors report the existence of permafrost at Mt. Taisetsu, Hokkaido, and disdiscuss the climatic significance of permafrost there from a viewpoint of the Quaternary palaecolimatology. Many researchers have observed that patterned grounds, especially sorted circles well developed on many gentle slopes and small depressions at Mt. Taisetsu. And recently it was reported that the networks of fissures of the ground which are similar to large scale ploygons on permafrost in Alaska were found at some places at Mt. Taisetsu. Those sorted circles and nets of fissures suggest the existence of permafrost which is believed to be either relict or recent.By our on-the-spot investigations at Mt. Taisetsu, permafrost was found on one of flat summits (2, 150m) by boring tests and geophysical methods. The maximum depth of the active layer was nearly 2m and the maximum depth of the lower limit of this permafrost was estimated to be 15m or larger. Its frozen soils consisted of weathered fine sands and gravels derived from an andesite bedrock, which are considered as frost-action products. Large sorted circles were form ed on the surface of permafrost.The mean annual temperature and degree-days in this area were calculated as -3.1°C and 2, 400 degree-days by extrapolations on the basis of meteorological data in Asahikawa. The estimated temperature and degree-days suggest that this area has the same climatic conditions as those in central Alasak, where discontinuous permafrost is distributed.Introducing the Popov's theory about the formation of an ice-wedge, we estimated the palaeo-temperature of the surface of the extended permafrost to be -7°--8°C (mean annual temperature) during a past colder period than present. Comparing the estimated chronology of the permafrost with the chronology of permafrost in Alaska and Siberia, and considering the field observations of fossil ice-wedge casts and polygons in Hokkaido, we may conclude that the permafrost at Mt. Taisetsu formed at the last ice age, after then gradually has become smaller, adapting itself to the present climatic conditions.

著者

岩田 修二

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.42, no.3, pp.181-193, 2003-06-01 (Released:2009-08-21)

参考文献数

53

被引用文献数

9 6

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面積は小さいが,日本アルプスは第四紀研究にとって重要な高山環境なので,そこでの研究は注目に値する.日本アルプスの削剥にとっては,大規模崩壊などの重力地形が重要である.その発生時期や,下流の河谷の埋積とどのように関係するかについてはまだ未解決である.最終氷期の氷河最大拡張期はMIS4~MIS5aであった.そして,最終氷期後半の氷河最大拡大時期はMIS2(北半球氷床のLGM)ではなく,MIS3の可能性が大きい.したがって,MIS2の氷河最大拡大期を想定して書かれたこれまでの垂直分布図や古環境地図は改訂を検討すべきである.日本アルプスにも,過去には山岳永久凍土が存在し,現在も局所的には分布することが岩石氷河の研究や地温観測から明らかになった.晩氷期と完新世の寒冷期における山岳永久凍土の地形形成や,植生に対する役割を再評価すべきである.最終氷期から完新世への移行期には,高山帯での崩壊が頻発したらしい.今後の研究の進展のためには,未発表の調査結果の印刷と公開現地検討会の開催が重要である.

著者

松原 彰子

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.31, no.4, pp.221-227, 1992

被引用文献数

1 3

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静岡県浮島ヶ原は駿河湾奥部に面し, 3列の海岸砂礫州が海側へ発達することに伴って, その背後に形成された低湿地である. 内陸側の2列の砂礫州は, 本地域の沈降運動のために, 低地の地下に埋没している. 最も内陸側の埋没砂礫州は, 一部微高地として認定することができ, 雌鹿塚遺跡はその上に立地している.<br>雌鹿塚は, 縄文時代中期から古墳時代中期まで営まれた遺跡である. 今回, 沼津市教育委員会によって, 雌鹿塚遺跡の本格的な発掘調査が行われた. その際, 埋没砂礫州の微地形, ならびに周辺の地質層序, 年代測定値, テフラ等の資料を得ることができた. さらに, 雌鹿塚遺跡周辺における自然環境の変遷と人間活動との関係について考察した結果, 浮島ヶ原への人間の進出が砂礫州の発達過程と対応すること, 火山活動や地殻変動が雌鹿塚を放棄させる原因となった可能性が大きいことが推定された.

著者

河村 善也

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.37, no.3, pp.251-257, 1998-07-31

被引用文献数

8 39

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第四紀における日本列島への哺乳類の移動を本州・四国・九州と北海道,琉球列島という3つの生物地理区に分けて考察した.本州・四国・九州地域では,長鼻類化石の生層序学的研究によって,次の3種のゾウが最初に出現した時期が明らかにされている.すなわち,シガゾウの出現は1.2~1.0Ma頃,トウヨウゾウの出現は0.5Ma頃,ナウマンゾウの出現は0.3Ma頃である.これらのゾウの出現は,それらが近隣の大陸地域から移入してきたことを示し,またそのような移入を可能にする陸橋の形成を示唆する.ナウマンゾウの移入期以後,本州・四国・九州地域は大陸や北海道からずっと隔離されてきたと考えられる.北海道では,化石の記録が本州・四国・九州よりはるかに少ない.北海道の後期更新世の哺乳類は,ナウマンゾウ,プリミゲニウスゾウ,ヤベオオツノジカといった3種の大型草食獣で代表される.そのうち,ナウマンゾウとヤベオオツノジカは,本州・四国・九州地域から0.3Ma頃に移入した可能性があり,プリミゲニウスゾウは後期更新世後半にシベリアからサハリン経由で移入したと考えられる.琉球列島では,更新世の化石記録は大部分が後期更新世のものである.琉球列島北部の後期更新世の動物相では固有の要素が卓越しているが,それらはおそらく更新世以前にこの地域に移入したものであろう.琉球列島南部の後期更新世の動物群は,中期あるいは後期更新世に移入した種類と,より早い時期に移入した種類から成り立っている.

著者

池田 碩 大橋 健 植村 善博

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.20, no.4, pp.329-330, 1982-01-20 (Released:2009-08-21)

参考文献数

8

著者

長田 敏明

出版者

Japan Association for Quaternary Research

雑誌

第四紀研究 (ISSN:04182642)

巻号頁・発行日

vol.19, no.1, pp.1-14, 1980-05-31 (Released:2009-08-21)

参考文献数

27

被引用文献数

2 2

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The subject of this paper is to establish the stratigraphy of deposits composing to Makinohara Upland, and also to discuss the landform evolution of the Makinohara Upland. The results are summarized as follows:(1). The terrace-forming deposit is divided into three beds, i.e, Furuya mud bed, Kyomatsubara sand bed and Makinohara gravel bed in ascending order.(2). The Furuya mud bed accompanied with the basal gravels is mainly composed of marine silt and clay filling the buried valleys (Fig. 10 and Tab. 1). The main part of the Furuya mud bed deposited in the narrow drowned valleys, during the early stage transgression, and covered uncomformably the Neogene semiconsolidated rocks.(3). The Kyomatsubara sand bed newly defined by this author was widely deposited in this mapping area as foreset beds at the maximum phase of the transgression (Fig. 9).(4). The Makinohara gravel bed mainly consists of widespread homogeneous fluvial gravels, the upper part of which is boulder gravel forming the alluvial fan named Makinohara.(5). Five horizons of buried topographic system are found under the Makinohara Upland; Buried surface I, II, III and IV (Figs. 8, 10) and Buried valley floor.(6). The Buried valley floor is the oldest topographic system filled with the Furuya mud bed. Two horizons of abrasion platforms (Buried surface I and II) are found cutting the slope of buried valley systems. The Buried surface I was formed just after the deposition of basal gravel of Furuya mud bed. The Buried surface II, on the Neogene strata was formed during the accumulation of upper mud part belonging to the Furuya mud bed (Fig. 10).(7). The Buried surface III covered with the Kyomatsubara sand bed is the most extensive among the three buried abrasion platform cutting the Neogene strata (Fig. 8 and 10).The level of the boundary between the Furuya mud bed and the Kyomatsubara sand bed nearly corresponds with that of the Buried surface III.(8). The Buried surface IV is the basal topography of the Makinohara gravel bed. Finally extensive rivers, laterally eroding the valley slope flew down onto the newly emerged coastal plain and slightly cut the Kyomatsubara sand bed (less than 5m) (Fig. 10). At that time, the Buried surface IV was formed as a basal topography of the Makinohara gravel bed.(9). The Makinohara Upland was constructed as alluvial fans by the Paleo-Oi River. The deposits forming the Makinohara Upland are defined to the Makinohara gravel bed.