Ceramic Clay deposits are widely distributed in Aichi and Gifu Prefectures., All of them belong to the Pliocene Seto group and lie upon granite and Palaeozoic siliceous rocks., Their parent materials have hither to been believed to be decomposition products of granite or granitic rocks., The origin of the various types of clays as called "Kira", "Gaerome", "Shironendo", "Kibushi" etc., has been ascribed to sorting during transportation of the weathered granitic materials by water., The writer studied this problem and as the result, he was led to a different opinion as mentioned below., In some district pumice sands or coarse-grained volcanic glasses, of which the fine part has been already altered to clay minerals of the kaolin group, are distributed in association with clay deposits, and in many clay deposits there are found some quantities of volcanic glass., From these facts, it is clear that the tuffaceous material has played a great role as the parent material of the clays., Near the margin of the depositional basin in granitic areas, there can be seen both kinds of clays produced from granite and from tuff, occurring in complicated relations., Both of these two kinds of clay minerals belong to the kaolin group, though they differ from each other in detailed mineralogical properties such as chemical composition and crystal structure., Namely, the clay minerals delived from granite belong to kaolinite and kaolinite-like haloysite, whereas those derived from volcanic ashes are referred to halloysite and endellite., It seems natural that the granite and the tuffaceus materials have been mixed within various rations during the period of deposition., The coexistence of some different types of clays can be explained, therefore, by the non-uniform mixing of granitic meterial and tuff under the complicated hydraulic conditions as generally seen in marginal areas of a lake.,

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The Yamatoda diatomaceous mudstone member (10∼15 m thick), which is characterized by the dominance of freshwater diatoms, unconformably overlies a two-pyroxene andesite and its agglomerates (Anamizu formation, F₂, Middle Miocene), and is disconformably overlain by the marine Hamada mudstone member., The Yamatoda diatomaceous mudstone member also contains several plant fossils such as Comptoniphtyllum sp., Liquidambar sp., etc., and its geological age is refered to later Middle Miocene (F₃)., By a detailed research on the diatom remains in the mudstone (Table 2), it is revealed that the marine diatom species (Actinocyclus sp., etc., ) are frequently found at the several localities in the eastern half, while the western half is characterized only by fresh-water species such as Melosira granulata, etc., Therefore, it is suggested that the Yamatoda diatomaceous mudstone member accumulated in a small lake which was connected with the sea (perhaps by a channel) on its eastern end., Latest the sea level rose gradually, and at last, marine water abruptly invaded the whole area, forming the interesting disconformable relation between the Hamada and the Yamatoda mudstone members (Fig 2).,

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Three problems on the geology of the south-western area of Sendai City are discussed with the results briefly summarized as follows: (1) The "Kagitori fault" is not really a fault, but represents a part of the werping axis which runs from Iwanuma to Kagitori via Ayashi to Okubushi., This tilting movement occurred after the deposition of the Tsunaki formation, and resulted in the formation of the deposition basin, where the Sendai group was deposited., (2) The horizon of the Mitaki andesite (lowermost formation of the Sendai group) corresponds to the upper part of the Tsunaki formation (uppermost formation of the Natori group)., Consequently, the hiatus between the Natori and Sendai groups is not so large as hitherto believed to be., (3) The facies of the Tsunaki formation changes laterally to that of the Yumoto formation.,

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四国の地質構造は最初日本海運動によつて形成され, 後太平洋運動によつて変形されたものであつて前者はprimary structureであり後者はsecondary structureである., 構造上四国を東・中・西の3部に分ち, これに加わる両運動現在の分布を見るに, 西部における両者の境界は著しく南に偏して宿毛-中村の線である., 然るに, 中部における南方よりの圧縮は南海々溝より結晶片岩帯に及び両運動の境界は, 三島・市ノ川間の中央線に取ることが出来る., 又東部における南方よりの圧縮は, 剣山々脈の上昇を促し, 更に淡路の南部に影響するのであつて, 両者の境界は御荷鉾層附近にある., 本文は特に四国アルプスの成因を論じ, 松山附近の重力異常と久万盆地における安山岩噴出の関係を述べている.,

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