The clue to and an advance in study of the Nohbi Tilting Basin has a social background of problems caused by landsubsidence in the Nohbi Plain. The Nohbi Tilting Block, a crustal block including the Nohbi Plain in the west to Mt. Sanage in the east, is characterized by Quaternary tilting movement (Figs. 1 & 2). The Nohbi Tilting Basin, which occupies a western half of the Nohbi Tilting Block, was formed by the Nohbi Tilting Block Movement, and is filled with the Quaternary Owari Group. Accompanied with progress of the tilting, the Owari Group was deposited under the control of glacio-eustacy, and is composed of alternating marine sediments during transgression and fluviatile ones during regression (Figs. 4 & 5). Topography of the Nohbi Tilting Block consists of Alluvial plain, uplands (terraces), hills and mountains toward the east (Fig. 3). The western margin is bounded linearly by the Yoro-Ise Bay Fault (Fig. 2). Rivers flowing within the tilted block tend to converge to the western margin (Fig. 3). In the Nohbi Tilting Basin, Quaternary formations related to the tilting dip westwards as a whole. Among these formations, older one inclines with a larger dip, and most of them become thicker and deeper toward the west (Figs. 5 & 6). The estimated rates of the tilting tend to have become larger in younger stage (Table 1). The Nohbi Tilting Block constitutes a part of the Chubu Tilting Block, which is a larger crustal block bounded by the Itoigawa-Shizuoka Tectonic Line on the east and the Tsuruga Bay-Ise Bay Line on the west. The Chubu Tilting Block Movement is a large scaled tilting movement mainly in the Quaternary. Major relief of the eastern part of Southwest Japan is characterized by the morphology of undulation trending in a NNE-SSW direction (Fig. 7). The undulated relief is longer in the western slope and shorter in the east, and is about 80 km in wavelength. Accordingly, the tiltings correspond to movements in the western slope of the undulated relief. Quaternary sedimentary basins such as the Nohbi Tilting Basin have been formed where the trough of Quaternary undulation superimposes on the Neogene sedimentary provinces stretching sub-parallel with the elongation of Southwest Japan.

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The author investigates the crustal movement and the formative process of the Muikamachi Basin through an analysis of the land-form in the Uonuma district, central Japan. The results are summarized as follows: 1) The detailed examination of summit level in this district and land-forms of the Sumon and liji volcanos, shows that the basement mountain of pre-Middle Miocene on the east of the Muikamachi Basin was devided into a number of blocks 20 to 30 kilometers long and uplifted with independent behavior, mostly tilting, for each blocks, resulted in the various elevations of block. 2) The comparative study among summit level and remnants of low-relief erosional surfaces in this district, indicates that a low-relief erosional furface named the Uonuma Surface was formed as the primary peneplain all over the surveyed area during the early Middle Pleistocene, and that the Uonuma Surface has been differenciated into the western Uonuma Hills and the eastern Muikamachi Basin due to fault displacement of the Shibata-Koide Tectonic Line since the late Middle Pleistocene. 3) The terraces in the Tokamachi Basin on the west of the westward-tilting Uonuma Hills are classified into four groups, that is, the higher terraces (Takaba, Taniage and Maibara I furfaces), the middle terraces (Maibara II and Unoki surfaces), the lower terraces (Honokizaka, Kaisaka and Shomen surfaces) and the Holocene terraces (Owarino I-II surfaces). The examination of extents scale and longituninal profiles of the terraces and the analysis on provenances of the terrace gravels and paleocurrents, show that the terrace surfaces from the Takaba to the Maibara II were formed as extensive fans of river that flowed into the Tokamachi Basin from the basement mountain on the east of the Muikamachi Basin. It means that the Muikamachi Basin did not yet appear in that time. 4) The terraces distributed in the Muikamachi and the Horinouchi Basin are classified into ten steps in order from higher to lower and correlated respectively to the terrace groups, in the Tokamachi Basin. The examination of longitudinal profile of the terraces in the Horinouchi Basin, indicates that the rivers in the Muikamachi Basin were flowing into the Horinouchi Basin beyond the divide of the Uonuma Hills during forming period of the Maibara II surface in the Tokamachi Basin, and then the rivers connecting these two basins disappeared through displacement of the Shibata-Koide Tectonic Line as at present. 5) Longitudinal profiles of the terrace surfaces and colluvial slopes in the Tokamachi, Muikamachi and Horinouchi Basin, lineaments and subsurface geology around the Muikamachi are investigated synthetically. The investigation shows that the mean vertical slip rate of the Sibata-Koide Tectonic Line, which is composed of some faults arranged in echelon of right hand, became a muximam when the middle terraces were formed and the Muikamachi Basin was remarkably deepened. Activity of the faults are estimated to be of the A rank. 6) The formative process of the Muikamachi Basin is divided into the four stages, that is, peneplanation of the Uonuma Surface (early Middle Pleistocene), germinating of the basin (late Middle Pleistocene), deepening of the basin (early to late Late Pleistocene) and filling of the basin with fan sediments (latest Late Pleistocene to Holocene).

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The Seto Group, late Miocene to early Pleistocene in age, is widely exposed in the Tono district, Gifu Prefecture, and the Owari district, Aichi Prefecture. Our studies have revealed structures of sedimentary basin of the Seto Group in the Tono district. The sedimentary basin is an assemblage of small collapse basins which are enclosed with high angle unconformities. These small collapse basins are quadrangular in shape, and their sides range from 500 m to 2 km in length. The first-stage collapse occurred in the late Miocene to generate the small sedimentary basins sporadically. Fine-grained sediment of the lower part of the Seto Group was supplied from the surrounding hinter land into the basins. Subsequently, the second-stage collapse took place in the early Pliocene to form a chain of small basins. These small sedimentary basins were linked up and produced a big river valley. The big river transported coarse sediment of the upper part of the Seto Group from its upper stream into the fluvial linked-basins. Further, we clarify the geohistorical relationship among the Seto Group, the Tokai Group, and Tokai-ko (Lake Tokai). The paleogeographic change is also discussed.

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The Kobiwako Group, Pliocene to Pleistocene in age, is distributed in the Iga and the Omi basins. The sedimentary basin of this group originated around the Ueno basin in early Pliocene times, about four millon years ago, and subsequently migrated to presentday Lake Biwa. Four stages are distinguished with respect to the migration of the sedimentary basin. The first to forth stages are represented by the sedimentary basins of the Ueno, the Iga and the Ayama Formations, of the Koga Formation, of the Gamo and the Kusatu Formations and of the Katata and the Takashima Formations, respectively. The basin in each stage is an association of the depressed fault blocks which are divided by the faults and flexures trending in north-northwest, east-southeast and north-northeast directions. Along the margin of the basin of each stage, steep angle uncomformities are common. Their traces are rather stright and trend in the same directions as the faults and flexures in the sedimentary basin. Debris flow and/or talus deposits consisting of poorly sorted angular to subangular gravels is common along the steep unconformities. Faults with same trends as those of the unconformity are usually found in the basement rocks covered by the steep unconformity. Thus it can be inferred that the sedimentary basin of the Kobiwako Group arose through fault movemens and rapid subsidence of the fault blocks, and that the northward migration of the sedimentary basin was controlled by sifting of the area of fracturing and subsidence of basements. Each block in the sedimentary basin appears to have been tilting during the deposition of the group, because the vertical profile of the sediments on each block shows a wedge-like shape. Not only lacustrine clay but also deltatic sand buried thickly up the subsiding zones on the tilting blocks. The sedimentary basin of the Osaka Group also shows fault block structure. Lateralvariation in thickness of the group indicates that subsidence of the basin progressed through tilting of the fault block since its embryonic stage. From above mentioned facts, it can be stated that the Pliocene to Pleistocene sedimentary basins in the Kinki district arose through block movements and tilting subsidence of faultblocks. Fault blocks composing the Pliocene to Pleistocene sedimentary basins in the Kinki dis-trict are sized about 30 km in the northern parts of the basins, and more than 10 km in the southern parts. But they are only a few kilometers in the middle part of the basins. Because the belt of small scale block coincides approximately with the boundary of basement geology between the Ryoke Complex and the Mino-Tamba Belt, such a decrease in dimension of fault block appears to have been affected by pre-Neogene geologic structures.

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In this paper the writer maintains the following four points of view; 1. During the geological times sediments were always concentrated and laied down in limited areas, i.e., sedimentary basins. All the present coastal plains and intramountain basins in the Japanese Islands are final products of the lowland that has been developed since the Cretaceous. Thus, sedimentary basin, coastal plain and intramountain basin in this case are included into a same category. 2. Two types of generative process of sedimentary basin are generally known. One is collapse, i.e., downthrowing of basement block to produce a depression bounded by faults. The other is subsidence, i.e., down-warping of basement to form a basinal depression. Giving several examples, the writer pointed out previously that down-warping of sedimentary basin was nothing else than a surface phenomena of underground fracturing or collapsing. In this respect, generation of a sedimentary basin due to subsidence would be synonymous with occurrence of a collapse under the ground. 3. The category of "Shogidaoshi (Fujita, 1951)" does not involve any genetic definitions, since it is a term defining a configuration of sediments of which depocenter shifts unidirectionally. Some people who do not accept the term "Shogidaoshi" want to replace it with the other terms such as "tilting block movement" or "Shogidaoshi" (unidirectional shifting of upheaval to bring migration of depcenter)". They, however, must have misunderstood the original definition of the term excluding its mechanism. 4. The law of "Shogidaoshi" is applicable to a developing stage of pre-existing sedimentary basin, not to a generative stage of new sedimentary basin. Incidentally, it rarely happens that a new sedimentary basin of exotic nature is generated just in front of unidirectional shift of a "Shogidaoshi". Such a case is accidental, being out of applicable extent of the law of "Shoeidaoshi".

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The Median Tectonic Line borders between the south foot of the Asan ranges and the Yoshinogawa valley in northeast Shikoku. A new description is given on the stratigraphy and geological age of the deposits in the Yoshinogawa valley and in the north foot of the Asan ranges. The newly defined Moriyama formation in the southside of Yoshinogawa valley floor includes the tuff layer 2.3±Ma Fission truck age in the lower part and the coarse gravel from Asan ranges of Izumi Group (the Cretaceous sedimentary rocks) that suggests the north wall of the tectonic valley had developped by the Late Pliocene. The schist gravels in the Plio-Pleistocene Mitoyo Group in the north foot of the Asan ranges have been belived to be derived from the Outer zone mountains south of the MTL before the time of uplift of the Asan ranges and the depression of Yoshinogawa valley. But our detailed lithologic analysis suggests that the schist gravels in Mitoyo formation originated from the west of the area along the Setouchi inland sea, because the arkose sand matrix and the small number of granite gravel were also included in Mitoyo Group in the foot of Asan ranges. The granitic materials might be from the Ryoke zone in the north. The FT dating made possible the correlation between the Mitoyo Group (Late Pliocene to Early Pleistocene by plant pollen fossil and FT age of tuff) in the north of the Asan range and the Moriyama formation in the south of the Asan ranges. The result suggests that the Asan ranges had already uplifted during late Pliocene. The same paleo-geomorphologic condition is presumed in the west part of Izumi ranges where the Plio-Pleistocene Osaka Group and Shobudani Group deposited. The thick fanglomerate called as "the Dochu Gravel Bed" develops in the north side of the Yoshinogawa valley. The age of the "Dochu Gravel Bed" have been thought to be the last glacial age based on about-30000-y.B.P. radiocarbon age. But the tuff layers 1± to 0.5±Ma FT age and the horizons of various pollen assemblage were newly found, and the new data indicate the age of Dochu Gravel Bed is the late of Early Pleistocene to middle Pleistocene. The revised stratigraphy suggests that the middle to later Quaternary tectonic movement may have been noticed too excessively to explain the differentiation of the Asan ranges and the Yoshinogawa valley. The occurence of Dochu Gravel Bed Group and some faults cutting and up-thrusting to the Dochu Gravel Bed suggests the tectonic movement of MTL had continued during middle and late Quaternary.

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Many sedimentary basin classifications are known, which are applicable to worldwide petroleum basins, but not to individual small basin in mobile belt. This paper proposes a new system of basin classification adaptable to the Late Cenozoic sedimentary basins in and around the Japanese Islands. Among those basins the three structural types are distinguished: (1) folding basin formed by synclinal subsidence of basin bottom, in some cases with plural depoaxes, (2) collapse basin generated by depression of a crustal block bounded with steep faults, and (3) tilting basin formed by down tilting of fault block, adjoining fault scarp of neighboring block. The many Late Cenozoic sedimentary basins in Japan can be classified on the triangle diagram with endmembers of collapse, tilting and folding basins, i. e. the CFT diagram, Most of the basins are plotted at the ends and the side lines of the diagram. Those at the central parts of side line of the diagram are called collapse-tilting, tilting-folding and folding-collapse basin, respectively. This tentative classification is expected to promote the feedback between structural description and structrural classification of sedimentary basins and the study of basin genesis.

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