Igneous activity of the Japanese islands from late Miocene to Pleistocene is divided into the activities of the following four stages; late Miocene, Pleiocene, early Pleistocene and middle to late Pleistocene. One of the activity of late Miocene is effusion of dacite and/or aridesite in several collapse basins generated at the upheaval parts of the Green tuff region and volcanic rocks of this time are mostly pyroclastic flow sediments of calc-alkali rock series. Another activity is effusion of andesite or basalt in the subsiding basins on the Japan Sea side. These activities are those of the last stage of the Green tuff movement. Igneous activity of Pleiocene has occurred in the limited areas of the Japanese islands, namely the northern Fossa Magna, southwestern Hokkaido, San'in areas and others. The activity of the northern Fossa magna area is most typical and has occured in the subsiding basins of the so-called Shin'etsu geosyncline. Volcanic rocks of the area are mostly calc-alkali andesites and some of them have gabbroic xenolith and hornblende and/or diopside megacrysts. Igneous activity of San'in area of this time is those of the Misasa and Matsue formations. The activity of the former has occured at the upheaval part and volcanic rocks are alkali basalt and calc-alkali andesite, on the other hand, the activity of the latter has occurred in the subsiding basin and is the activity of alkali basalt. Although both activities have occurred at different geological environment, they are the same with respect to the beginning of the activity in the Circum-Japan Sea alkaline province. Igneous activity of early Pleistocene has also occured at limited area, which mainly are the northern Fassa Magna, Hokkaido, central Kyushu areas and has two characteristic modes of effusion except basalt lava flow of the San'in area. One is effusion of the so-called flat lava of calc-alkali andesite at the upheaval part and another is eruption of pyroclastic flow of dacite which has occurred at the central Hokkaido area and the Shirakawa-Aizu area of the northeastern Japan. Quaternary volcanoes having several volcanic chains along the present arc-trench systems have been formed from middle Pleistocene to recent. On the igneous activity from late Miocene to Pleistocene, that of early Pleistocene is most characteristic on the points of spacial distribution and mode of effusion. This activity is not related to the Green tuff movement, but may be related to the Island Arc movement proposed by FUJITA (1970). Main field of the activity of this time may be situated in the area of the arc-junction of the Japanese islands.

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The voluminous volcanic products of the late Miocene to Pliocene time are widely distributed in the western part of Gunma Prefecture. They are mainly composed of pyroclastic rocks, lava flows and intrusive rocks that range in composition from basalt to dacite. The andesitic lava flows and pyroclastics are most abundant among these volcanic products, which petrographically belong to the hypersthenic rock series. A little amount of siliceous basalts and dacites associated by andesitic rocks also have petrographical character of the hypersthenic rock series. The early stage of the igneous activity of the late Miocene time in this district is characterised by the eruption of a large amount of andesitic lava flows and pyroclastic rocks from many volcanic craters. In the middle stage, many volcanic rocks were intruded in the area around the volcanic craters and they occur in the form of dyke, sheet, volcanic neck and massive body. A remarkable feature in the final stage magmatism is the intrusive activity of the holocrystalline rocks such as diorite, quartzdiorite and porphyrite, which form the so-called volcanoplutonic complexes in some localities. On the other hand, the volcanic activity during the Pliocene time is restricted to the eruption of andesitic lava flows and pyroclastic rocks from the volcanic craters located in the western part of this district. It may be concluded, therefore, that in this district the calc-alkaline magmatism was active during the late Miocene to Pliocene while mode of the igneous activity in the late Miocene was slightly different from that in the Pliocene Age.

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Late Neogene volcanic rocks in the northern-eastern part of Nagano Prefecture were distributed in two regions separately. One is in the western area of the Central Uplifting Belt (Fossa Magna Reserch Group, 1958), the other is in the western area of it. In this paper we arranged these volcanisnis from the view point of tectonic developments. The Middle Miocene to Early Pliocene marine sediments has a wide distribution in the western area of the central Uplifting Belt. Depositions and distributions of these materials may be controled by the basin-forming movement during the Middle Miocene to Early Pleistocene time. The Komiji, the Takafu and the Hikage synclines were main sedimentary basins which generated during this time. The syncline axes in these areas has a NNE-SSW direction. During the Middle Pliocene to Late Pliocene time, a new tectonic movement may be generated in this area. This movement is characterized by the basaltic-andesitic volcanics which were composed of pyroxene andesite-hornblende andesite lava flows and pyroclastics. They were restricted in Hijiriyama, Arakurayama and Togakushiyama districts. It is remarkable that the Pliocene volcanism had taken place in this depression area with NE-SW direction. Because the NE-SW direction in the western area seems represents the Late Pliocene-Early Pleistocene tectonic movement. On the other hand, the characters of tectonism and volcanism in the eastern area of the Central Uplifting Belt seems very different from those in the western area. Since the Middle Miocene (Bessho stage), this area might have a tendency of uplifting, so during the Late Miocene to Early Pliocene time there might be no sedimentary basins in the greater part of this area. The Komoro and The Enrei sedimentary basins had being in existence in the Middle Pliocene to Early Pleistocene time. The former is in NNE-SSW tectonic direction, the later one is in NW-SE direction. In these basins, violent volcanisms had taken place rapidly and it supplied a large quantity of pyroclastics and lava flows. The upper part of them was characterized by so called flat lavas, which consist of mainly hypersthene augite andesite and hornblende andesite lava flows.

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Andesitic pyroclastic rocks, which were piled up by submarine volcanic activity at Pliocene, are broadly distributed in the Yoneyama district. Pyroclastic rocks, 2000 m in thickness, are exposed in wide scope, about 20km square. There are some facts of the tectonic movement at the beginning of volcanic activity, that was represented by upheaval-fracture, depression-submarine volcanism. 1) At the uppermost Miocene, there are exposed the Yoshio conglomerates, which were overlaid Pliocene pyroclastic rocks and they were mainly consisting of gravels of Pre-Tertiary. 2) There are many faults in Miocene system which were overlaid pyroclastic rocks. These faults concentrate on piedmont, near Tanne-Ogaya at northwest of Yoneyama mountain. Approaching closely to Yoneyama mountain, there exist blocklike faults. 3) At Tanne and Ogaya, northwest of Yoneyama mountain, pyroclastic rocks which were the lowest part of Yoneyama formation, were unconformably piled up on Miocene system which were block-like destructive. At the seaside of Yoneyama, pyroclastic rocks and Miocene system exist closely conformably at some points, and unconformably at others. 4) Pyroclastic rocks were piled up by the submarine volcanic activity in the early times.

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The oldest volcanic activity of the Yatsugatake is represented by the Yachiho Formation which lies conformably on the Aihama Formation probably of the Early Pleistocene age. The Yachiho Formation is developed extensively in the northeastern piedmont area of the Yatsugatake Mountains and is composed of volcanic products erupted from Old North Yatsugatake of the Early Pleistocene age. The center of volcanism of the Old North Yatsugatake is estimated to have been some where in the northern part of the Yatsugatake Mountains. The deposition of the Yachiho Formation was followed by a long cessation of volcanic activity, and the whole area of the Yachiho Formation suffered from general denudation to produce a vast erosion surface. In the Middle Pleistocene time, volcanic activity revived again and the thick Yukawa Formation, of which materials were supplied from several volcanic centers of the Central and the South Yatsueratake. was formed. Toward the end of the Middle Pleistocene time, such volcatic mud flows as the Chikumagawa and Uminokuchi Mud Flow Deposits were formed. At the same time, certain parts of South Yatsugatake were collapsed to yield volcanic ejecta of somewhat more basic varieties than others. The Nisikawa Scoria Formation is the most representative of them. Late Pleistocene began with the eruption of acidic volcanic rocks, of which the representative is those of the Yanaike Pumice Flow Deposits that are extensive in the Central Yatsugatake and overlie the Hozumi Terrace gravel bed comformably. A remarkable fact is that most of volcanic products supplied from the Central Yatsugatake area are represented by acidic varieties through Early, Middle and Late Pleistocene. The last stage of the volcanic activity or: the Yatsugatake is shown by lava domes of the North Yatsugatake, and also by explosion craters along the east flanc of the North Yatsugatake. They are understood to be of Wiirmian age.

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The Neogene and Quaternary volcanic activities in Shimane prefecture, western San'in district, are studied, and the results are summarized as follows. The Neogene volcanic activities are able to divide into two parts; are Green Tuff activities and Pliocene volcanic activities. The Green Tuff activities can be observed in the middle and lower Miocene strata, from Daishima to Onnagawa in stage. They are characterized by andesites and dacites activities, of being belong to hypersthenic rock series. However, pigeonitic basic andesites took place in earliest Daishima stage, and also alkaline olivine basalts in latest Onnagawa stage. The volcanic activities in Pliocene period are simply characterized by alkaline basalts activities. The Quaternary volcanic activities are composed of hypersthenic dacite and alkaline olivine basalts; the former is so-called "Daisen volcano system".

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The writer refers to the geological analysis of the magmatic uplift from the latest Oligocene to Pliocene in the Green-tuff orogenesis, and the block uplift from Pliocene to Holocene in the Island Arc diastrophism.

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In order to get the whole phenomenon of the igneous activity at Late Cenozoic age, the volume estimation of the volcanic materials formed in each stage of Late Cenozoic age carried out by the auther. Volcanic activity of the Middle Miocene (Nishikurosawa and onnagawa stage) is represented by the bimodal volcanism of basalt-rhyolite assiciation. On the other hand, acid volcanism such as dacite ignimbrite succeeded from Funakawa to Kitaura stage, mainly in the Backborn range of Tohoku. It became again violent at the end of the Shibikawa stage. Volcanic materials derived from the Quaternary volcanism are in large amount and show the unique episode in volcanic activity of Cenozoic age. It is a noteworthy that about 80% of the Quaternary volcanic materials was derived from andesite magma.

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In the Chugoku and Shikoku provinces, are extensively distributed various kinds of the late Cenozoic volcanic rocks as follows. (1) Calc-alkaline volcanic rocks derived by the volcanism associated with the "Gree Tuff Crustal Movement" in the San'in and Setouchi districts (middle to late Miocene). (2) Alkaline volcanic rocks mainly composed of basalts in the San'in district (the so called "Circum Japan Sea Alkaline Petrographic Province") and the Chugoku mountainland (late Miocence to Recent). (3) Calc-alkaline volcanic rocks which formed the volcanoes beloging to the so called Daisen Volcanic Zone in the San'in district (Quaternary). The middle to late Miocene volcanic activity might have been controlled by the structure in the direction of the Honshu arc. On the other hand, in the Pliocene to Recent time (especially middle Pleistocene to Recent) the volcanic activity has occurred mainly in relation to the structure of north-south trend, which crosses the Honshu arc direction. These evidences may suggest that the volcanisms of the above two periods have occurred in relation to the different crustal movement, respectively. Considering from many published chemical analyses, it is possible to point out the following chemical differences among the late Cenozoic volcanic rocks in these provinces. (1) There is a clear distinction of the chemical features between the middle to late Miocenct calc-alkaline volcanic rocks occurring in the San'ir and Setouchi districts. The latter have highei contents of alkalies, especially K2O, than those from the former. (2) Similar chemical difference is also observed in the alkaline volcanic rocks from the Pliocene to Recent in the Chugoku province. In this case alkaline volcanic rocks from the Sanyo district are richer in alkali contents than those from the San'in district. (3) It may be noticed, moreover, that the Pliocene to Recent calc-alkaline volcanic rocks in the San'in district have higher alkali contents than those of the middle to late Miocene in the same district. The above first two evidences may conflict with the general tendency in the chemical character of the island arc volcanic rocks, and seem to be inconsistent with the genetical interpretation based on plate tectionics held by JAKES-WHITE (1968,1972) and many others.

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Mizoro-ga-ike is a small pond of about 9 ha in area. It situates at the northern margin (about 75 m above sea level) of the Kyoto Basin which belongs to the warm-temperate zone. The pond is famous for the floating island vegetated by bog mosses and for various plants of over 100 species including many insectivorous plants and relict plants such as Menyanthes trifoliata L. as might survive from the Wiirm Glacial Stage. Mizoro-ga-ike Reseach Group has performed a study of the pond to clarify the present status and history of the pond intending to conserve the pond. The results are summarized as follow. 1) 132 species of Bryophyta and Tracheophyta belonging to 104 genera of 62 families are confirmed in the pond. Considering the distribution and the life condition of these plants, the pond is divided into four parts, that is, floating island, marginal part of floating island, coastal part of emerged plants and part of aquatic plants 2) The pond is in the valley presumably developed by the differential erosion of the shale beds and chert beds. The mouth of the valley was choked up by the developing fan of River Kamogawa, and the valley gradually changed into the pond. 3) The bottom sediments are composed of silt layer including angular gravels of chert, peat layer and layer of plant remains constituting the floating island in ascending order. The peat layer attains to 644 cm below the water level at the lowest. Three volcanic ash layers were confirmed in the sediments. 4) The history of the pond is divided into four stages, that is, the stage of small swamps, formation of pond, pond and swamps, and pond containing the floating island. The genesis of Mizoroga-ike goes back at least to the Wiirm Glacial Stage. About 7,500 years ago during the second stage, sand and gravel masses, which might be derived from the River Kamogawa, were carried into the pond. 5) Seven pollen zones are distinguished in the sediments, that is, Conifer-Betula, Lepidobalanus, Lepidobalanus-Celtis-Aphananthe, Cyclobalanopsis, Cyclobalanopsis-Pinus-Cryptomeia, Pinus-Cryptomeria and Cryptomeria zone in ascending order. Menyanthes trifoliata has existed since the stage of small swamps and is considered to be relict plant from the Wlirin Glacial Stage. 6) The eutrophication of the pond is going on in these days. It might be caused by the facts that water from the catchment area was cut off by the road around the pond and that filthy water produced by man's action came to flow in. In spite of an invasion of many plants such as naturalized plant, the native kinds of plants in the pond still keep their habitats. As one of the reasons, the inflow of the clean service water might contribute to buff the pollution.

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