In order to clarify sedimentary environment of the latest Pleistocene to Holocene sediments, Chuseki-so, geologic core of 33 m (HU-SRN-1) and 9 m core (AEM-1) in length were obtained at the Sarufutsu, northern Hokkaido. Radiocarbon dating, electrical conductivity measurement, diatom analysis and lithofacies division were carried out on the cores. Results of diatom analysis of the HU-SRN-1 core show the sedimentary environment changed fresh waters, brackish waters and fresh waters in ascending order, and seawater inundation during Holocene transgression occurred at 27 m in depth (15.2 m below sea level) at ca. 8,990 cal BP. Correlation coefficient in the HU-SRN-1, ca. 0.38, is computed by electrical conductivity and salinity index, determined from diatom assemblages. Distinctive features in curved lines of salinity index infer possibility of stratigraphic correlation of Chuseki-so in two different areas, Ishikari, central Hokkaido, and Sarufutsu.

A deep drilling was performed by Otsu City at Ogoto on the southwestern shore of Lake Biwa, and the core samples of the underlying Ogoto Granite were collected from 918.5 m to 1,801 m in depth. This granite is located between the Hira and Hiei Granite plutons. The Ogoto Granite consists of the following two rock types; a medium-grained, porphyritic hornblende-biotite granite to granodiorite and a fine-grained, porphyritic hornblende-biotite granite to granodiorite. The modal composition, bulk chemistry and a K-Ar age (71.2±3.6 Ma) suggest that this granite is a member of the late-Cretaceous ring complex around the southern Lake Biwa, whereas it differs from the Hiei Granite and the adakitic granites, distributed to the northwest of this pluton, in regard of their lithology, minor and trace element chemistry and age.

In the mid-Honshu Arc of the Japanese Islands, intense acidic magma activity happened during the late Cretaceous era. Because this sticky magma fluid mass must have bent the earth crust by pushing at the time of swelling, the Conrad discontinuity which was a weak aspect must have been split. As a result, acid magma soak into its slit, and it is thought that the middle earth crust with bullet plasticity like properties was formed. Moreover the rock sequence developed near by the Moho discontinuity was cracked by the upward pressure of consequence of swelling of this magma fluid. Above mentioned cracks developed in the earth crust spread from before in the earliest Miocene because of the enormous andesite magma swelling. After the late Miocene, andesite, diorite and dacite magma performed upwelling in sequence. At that time, the middle earth crust where sticky and hard diorite magma invaded became particularly thick. In addition, high-plastic dacite magma was poured into the earth crust, and the lower earth crust thickened. As a result, the upper earth crust and a sedimentary layer were pushed up widely and was formed a shield-shaped upheaval in the mid-Honshu Arc subjected to stresses which brought about swelling of enormous magma mass. On the other hand, the middle earth crust laid an igneous plume and brought up an isolated upheaval.

Cenozoic uplift of the Fossa Magna area began at the end of the middle Miocene, with general uplift continuing to the late Miocene. At this time there was violent volcanic activity in the vicinity of the uplift axis, with the formation of numerous volcanic collapse basins. The volcanic collapse basins form theprimary arrangement, with an oblique echelon secondary arrangement. The formation of echelon fractures can be explained by the extension zone due to uplift of the crust by vertical ascent of melt. In the raised central axis, where Miocene granitic activity, late Miocene volcanic collapse basins, Quaternary volcanic activity, and so on are seen, the Curie point depth is shallow with a higher crustal heat flow rate, which formed a high temperature zone (volcano-plutonic high thermal zone). On the other hand, from the data such as seismic distribution, seismic wave velocity structure, seismic wave tomography and the like, it is assumed that melt exists under the central part of the uplift, and the seismic low velocity layer is seen at depths of 30 to 50 km, or 20 to 60 km. These are in concordance with the formative mechanism of volcanic collapse basins obtained from geological surveys. After partially melting in the mantle, molten material accumulated between the lower crust to the uppermost mantle and this molten material flowed upward along ruptures in the crust (formation of magma group). It is assumed that the uplift of the raised central axis was caused by the formation of such a melt and the resultant magmatism.

Various late- and post-Pliocene strata are distributed in the hills and along the rivers of the western Kanto Plain. We describe the YAO Tephra of the Hanno Formation, the SYG Tephra, the SGO Tephra in the Sayama Formation, and the SSI Tephra in the Bushi Formation. Through wide scale comparison, we were able to determine SYG is comparable to the approximately 1.7 Ma Tsuike Volcanic ash Layer (TsA) distributed in the Niigata region. The SGO Tephra 20 m above the SYG Tephra is correlative to the E1 Tephra in the Bushi Formation and to the HU

₁ Tephra in the Tama Hills. The SSI vitreous tephra found just below the E1 Tephra is correlative to the HU₂ Tephra of the Tama Hills, and also correlative to the Kd25

Tephra of the Boso Peninsula aged about 1.65 Ma.

The tephrostratigraphy of western part of the Kanto Plain can be described in detail. We discuss the tectonics of the western part of the Kanto Plain by comparing sedimentary age, and dip and strike of each stratum. As a result, we consider that there was remarkable uplift of the Kanto Mountains 2.6-2.5 Ma, supplying a thick layer of sediment from the Kanto Mountains to the Kanto Plain, and this is still underway.

The “isolated hills” are situated in the western margin of the Echigo Plain, separated from the mountainside slope by a prominent back lowland. Following a detailed field survey, a formation model for the isolated hills is proposed, and the deep-to-shallow structures of the marginal active faults in the isolated hills are also discussed.

The marginal fault systems in the uplifted mountain change its structural feature from deep-high-angle fault to shallow-thrust. The structural features of marginal fault systems in the uplifted massif change from high angle faults at depth – “deep-high-angle faults” into the uplift near the surface – “shallow-thrust” at the top of the massif, high-angle normal faults are formed due to the tension field from strong uplifting. Toward the plain, a hill or bulge, formed due to the compression field of the reverse thrusts. Following this, the “isolated hills” formed in a graben-like back lowland due to the tension field in the border part between the back mountains and the hills. At the top of the isolated hills, small-scale high-angle normal faults and tension fractures are formed due to a weak tension field. The isolated hills are divided into several blocks by these faults.

In this model, the main block fault, a high-angle normal fault, formed in the back lowland between the back mountains and the isolated hills. A thrust branching from the main block fault formed on the side of the hill facing the plain. The isolated hills are controlled by the amount of uplift of the back mountains, and forming at the foot of the highest peak – the highest ridge of the back mountains. The stronger the back-massif uplifting, the greater number of isolated / the "multiple isolated hills" formed, since a multiple thrust system formed on the plain-ward side.