While on a tour of research in the north central part of Chiba-ken, known as Imba-gun, the writer found two hundred and nine sites of stone-age remains.According to patterns on the pottery and their forms, they were classified into eleven types.He has then endeavored to show which type occupies what part of the precinct.Some of the sites cover a wide area, while others are quite small.It is generally supposed that the former type is older than the latter.He hopes that this work will supply some data in the study of the geographical distribution of types of stone-age pottery in this County.

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Since VAN TIEGHEM found bacteria in fossils of plants in the year of 1879, many students found various bacteria of geological ages. The author also tried last year a bacteriological research of the Lower Pleistocene deposit of Nishiyagi beach in the suburbs of Akashi City. R. Katsunuma once found a sporforming Bacillus in Yoshiko shellmound with Jomonpottery. The author tried detailed bacteriological researches in various layers in three neolithic shelImounds with Jomonpottery in Kanto district, Okadaira in Ibaragi, Ubayama in Chiba Pref. and Kyu-Honmaru in the Imperial Palace in Tokyo. Some completely closed shells and mud were sampled from various layers by aseptic method, and aerobic bacteria were cultivated with normal agar medium (pH 7.0), anaerobic with glucose blood agar and both aerobic and anaerobic with thioglycolacidmedium. The species of bacteria were 52, and except for a few curious species the rest were identified to be common soil bacteria ; 14 Micrococcen, 1 Staplylococcus, 1 Gaffkya, 1 Aerobacter, 8 Achremobacters, 1 Flavobacterium, 24 Bacillen and 2 Clostridia. But the numbers of bacteria in shells are obscure except for two found in the Imperial Palace, that is the one 235 and the other 330. The more mud in completely closed shells increases in amount, the more numbers of bacteria increase. Anaerobic bacteria were all facultative. In shellmound bacteria live even in the depth of 370cm, and the species do not vary by the depth of the soil. However hard the shells are closed, some quantity of mud was found only in relatively shallower part. Ubayama shellmound is too shallow to research the bacteria in the shell, and Kyu-Honmaru had been partly put out of order. Even if new species were found in Ubayama and Kyu-Honmaru, we could not define them those of the neolithic age. Neither in the mud and shells of the scarcely mudded shell layer of Okadaira A Point, nor in the shells of the underlying mud containing shell layer, there could be found any bacteria. Those shells which contained no bactrtia did not contain much mud either. According to the stated fact, the author concluded that no sporforming bacteria of neolithic age could survive in Japan.

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There are about 103 shellmounds so far found in Japan which produce Haliotidae. Almost all of them are "H. gigantea GMELIN" We have few records available reporting how they were discovered. But it is most probable that the prehistoric men were attracted by the pearly colour of this shell. These ancient people adopted them as food and then as materials of implements and ornaments, lastly as a charm attributing some magic power. We Japanese use "Noshi", the animal of the shell boiled and dried, as a indication of presents. This custom is believed to originate in very early times. It is presumed that in earlier ages their consumers were limited to coast-side inhabitants who collected those shells in the neighboring sea and then the demand expanded to the inland areas in the later prehistoric ages. Some of these cases suggest us the way and the speed of the transportation of this kind of shells.

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Kozu-shima, which belongs to the northern subzone of the Fuji Volcanic Zone, is one of the Seven Izu Islands and is situated about 160km south of Tokyo. In this report, the author intends to clarify the volcanic geology of the island. The main results are as follows: 1) The rhyolitic volcanic activity (soda-rhyolite) in the latest Pleistocene to the Holocene age in the island can be divided into three stages. The activity of the first stage occurred under shallow submarine enviroment and formed several islets. The second stage is characterized by extrusions of a large amount of pyroclastic rocks and several lava domes. Some activities might have occurred on land. The channels between the islets made in the first stage were filled with the pyroclastic rocks of this stage. The third stage activity occurred on land and made five lava domes. 2) The eruptive centers of biotite rhyolite are arranged in a NW direction. 3) Many fractures and lineaments are obsered in the island. The fractures can be divided into three kinds as follows: a. normal fault: NS (strike), ca 60°W (dip) b. fault: ca NW, ca 90°c. fault: ca NE, ca 90°4) Alignment of domes of biotite rhyolite agrees with the NW-trending fault in direction. The relation between the volcanic alignment and the fractures is discussed at the last part.

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房総半島南東岸,南三原～相ノ浜間の海岸段丘面は,千倉付近を模式地として,高位より,岡瀬田面,寺庭面,平館面,瀬戸浜面の4面に大別される.これらの海岸段丘形成期の相対的海面変動については,おもに各面を構成する堆積物の特徴から,岡瀬田面の形成(縄文海進の頂期)以降,一方的に海面が低下し現在に至ったのではなく,寺庭面形成期(3,500年前ごろ)に海進が認められ,小規模ではあるが海面そのものの上昇があった可能性がある.調査地域のように,地殻の隆起速度が大きい地域でも,地形発達に小規模な海面変動が影響している可能性は十分考慮されるべきであり,これを無視して,地震隆起の累積という観点だけから段丘の発達を論ずることは危険である.

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Six different types of shallow water molluscan assemblages have been distinguished from the embayment deposits accumulated during the maximum stage of the post-glacial Jomon Transgression (ca. 6, 500-5, 000y.B.P.) in the southern Kanto, central Japan. These assemblages are also recognized in the embayment deposits of the very early stage as well as in the later stage of the transgression. In detail, however, their rise and fall are in harmony with the sedimentary history during transgression. In the early stage of the transgression, ca. 10, 000-7, 000y.B.P., the Crassostrea gigas-Anadara granosa-Batillaria zonalis assemblage and the Dosinella penicillata-Paphia undulata-Anadara broughtonii assemblage predominated in accordance with the development of muddy facies on the bottom of drowned valley. On the contrary, the sandy bottom assemblages, such as, the Meretrix lusoria-Mactra veneriformis-Umbonium moniliferum and the Meretrix lamarcki-Umbonium gigantium-Glycymeris albolineata assemblages, became dominant after the maximum stage of the transgression, from about 4, 500 to 2, 000y.B.P., during the reclamation stage of the embayment by the sandy materials provided from the adjoining rivers.
The intertidal assemblage, the Crassostrea assemblage, found in the innermost part of the bay is characterized by the association of several warm water species. Two steps of invasion of the warm water species are recognizable in the southern Kanto region. At the first step, ca. 9, 500-8, 700y.B.P., Anadara granosa, Anomalocardia squamosa and some other warm water molluscs appeared following the advancement of the Crassostrea assemblage into the embayment. The second step is at the beginning of the maximum stage of the Jomon Transgression, about 6, 500 to 6, 000y.B.P.. Molluscs of the tropical nature are the invaders of this step. They are represented by Ostrea pauluciae and Tellinimactra edentula. These warm water species rapidly declined in the later stage of maximum transgression, between 5, 000 and 4, 000y.B.P., and most of the species disappeared after 4, 000 years. Cause of disappearance of the warm water species has been said to be the lowering of water temperature. But it is known that the main cause of the disappearance is most probably attributable to the disappearance of their habitats, shallow muddy environment, rather than the lowering of water temperature.
There are many shell-mounds formed during the Jomon Era along the west coast of Tokyo Bay. Their situation and duration, relative abundance, and the change in species composition of shells can be explained by changes of paleogeography, sedimentary facies, and associated molluscan assemblages in and adjoining coastal areas of the embayments formed during the Jomon Transgression.

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