Earth Science (Chikyu Kagaku)

Some Problems on the Geology of the Shimosueyoshi Upland

Kanto Quaternary Research Group

Article type: Article
1970 Volume 24 Issue 5 Pages 151-166
Published: September 25, 1970
Released on J-STAGE: July 26, 2017

DOIhttps://doi.org/10.15080/agcjchikyukagaku.24.5_151

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It is generally said that the Shimosueyoshiformision distributed at the Shimosueyoshi upland in Yokohama and its vicinity were deposited at the most extensive marine transgression called the Shimosueyoshi Transgression. Besides, some unsettled problems have been left intact. For the purpose of re-examination, our group has made some field investigation about the Shimosueyoshi formation. The results are as follows; (1) The Shimosueyoshi Loam, which covered the Shimosueyoshi formation conformably, contains many distinctive pumice layers. They are distinguished with each other, and their lithofacies are mentioned. (2) The marine sediments previously defined as the Shimosueyoshi formation are divided into two formations which deposited at respective phases. The upper formation is the Shimosueyoshi formation proper. The lower may be correlated with the Byobugaura formation distibuted in the south area of Yokohama city, and is newly named the Tsurumi formation. (3) From examinations of deposits and fossils, it is assumed that the sedimentary environment of the lower member of the Shimosueyoshi formation was a bottom of narrow bay such as drowned valley, besides the upper member deposited in a wide and shallow bay connected with open sea. (4) An old dune were found by us in the suburbs of Yokohama. It seems that the dune constructed at the time of the Tama Loam. (5) On the basis of some additional data mentioned above and others, a hypothetical curve of sea-level change through late Quaternary are drawned.

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On the Punctations scattered over the Shell Surface of Glycymeris (Veletuceta) albolineata(LISCHKE)

Matsutaro SHIBATA

Article type: Article
1970 Volume 24 Issue 5 Pages 167-170d
Published: September 25, 1970
Released on J-STAGE: July 26, 2017

DOIhttps://doi.org/10.15080/agcjchikyukagaku.24.5_167

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Glycymeris (Veletuceta) albolineata are characterised by having the white radial lines and the rows of punctations, and are discriminated from G.(V.) vestita by the presence of the punctations scattered over the shell surface. The punctations are in two to four rows between two neighbouring white radial lines and are also in a line along the growth line. They do not distribute within 1 cm. from the ventral margin towards the dorsal side and gradually become indistinct near there. The distribution field of the small canal structures also coincides with that of the punctations. Comparing the inner surface of the shell to the limit of the distribution field of the punctations and the small canals, their distribution is limited inside the pallial line, that is their distribution coincides with the limit of the distribution of the inner layer. Small canals are scattered both inside and outside a punctation but several large canals are always found in a punctation. These canals are larger in width near the shell surface but in deeper part of the shell they have the same width as the smaller canals scattered outside the punctations. Thus the punctations might be assumed as the structure which was formed by several peculiar epitherial processes of the mantle after the shell formation had been finished.

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Pollen Analysis of the Lower Part of the Osaka Group atSenriyarna, Osaka

The Reseach of Younger Cenozoic Strata in Kinki District, Part 16

Akiko TAI

Article type: Article
1970 Volume 24 Issue 5 Pages 171-181
Published: September 25, 1970
Released on J-STAGE: July 26, 2017

DOIhttps://doi.org/10.15080/agcjchikyukagaku.24.5_171

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A pollen analysis was made for the samples obtained from the Lower part of the Osaka group at Senriyama, Osaka. The results are as follows; 1. Of the genera which are of the Tertiary type, Metasequoia, Ginkgo, Liquidambar, and Pseudolarix(?) disappeared in horizons ranging Senriyama tuff to Ma2. The horizons of extinction are Senriyama tuff for Pseudolarix(?), Ma0 for Ginkgo, and a nonmarie layer below Ma2 for Liquidambar, and Ma2 for Metasequoia. 2. The Lower part of the Osaka group is divided into five zones which are named A, B......, E zones from below in the present paper. The C zone corresponds to the Lower Metasequoia sub-zone of OD-1 Core (TAI, 1966), the D zone the upper Metasequoia sub-zone and the E zone the Fagus zone. 3. The D zone is considered to be of the age of extinction of Matasequoia. Accompanied by a decrease in Metasequoia, Cryptomeria began to increase at the top of the C zone; Metasequoia died out in Ma2 layer and was replaced by Cryptomeria. 4. The pollen flora of nonmarine beds found in the D zone suggests the Lowering of temperature. Therefore it is considered that in the D zone (Upper Metasequoia sub-zone) nonmarine beds are deposits of the age of lowering in temperature whereas marine beds were deposited in warmer age.

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New Occurence of Devonian Trilobites from Fukuji, Gifu Prefecture, Central Japan

Hitoshi KOIZUMI, Shigeo KAKEGAWA

Article type: Article
1970 Volume 24 Issue 5 Pages 182-187
Published: September 25, 1970
Released on J-STAGE: July 26, 2017

DOIhttps://doi.org/10.15080/agcjchikyukagaku.24.5_182

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Among 15 known species of trilobite from the Middle Paleozoic rocks in Japan, 9 species have been reported in the Devonian. Here we can add to them 4 species which were found in the Fukuji Series in Gifu Prefecture as follows: 1. Gravicalymene? sp. 2. Crotalocephalus sp. α (small form) 3. Crotalocephalus sp. β (large form) 4. Scutellum sp. Of the first species some cranidia, hypostoma and pygidia are known as the first occurrence in our country. Two forms of Crotalocephalus seem to be allied to the Crotalocephalus species reported by KOBAYASHI & IGO (1956). However, they were obtained from the limestone apparently lower than the latter's horizon. Scutellum species is represented by a fragmentary but characteristic pygidium.

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The Discovery of Orthoquartzite Grabels from the Shimanto Supergroup in Southern Kyushu

Tetsuro HARADA, Takao TOKUOKA, Hiroyuki SUZUKI, Ikuo YOSHIMURA

Article type: Article
1970 Volume 24 Issue 5 Pages 188-190
Published: September 25, 1970
Released on J-STAGE: July 26, 2017

DOIhttps://doi.org/10.15080/agcjchikyukagaku.24.5_188

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¹⁴C Age of the Handa Purmice Flow, Kujyu Volcano Group

¹⁴C Age of the Quarternary Deposits in Japan

Yukio MATSUMOTO, Masao HAYASHI, Tatsuo YAMASAKI

Article type: Article
1970 Volume 24 Issue 5 Pages 190-191
Published: September 25, 1970
Released on J-STAGE: July 26, 2017

DOIhttps://doi.org/10.15080/agcjchikyukagaku.24.5_190

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