The Upper Pleistocene deposits, the Higashi-Chitose, Kakuta, Moseushi Formations in ascending order, are distributed in the Yuni-Abira Low Land, eastern end area of the Ishikari Low Land. We redefined the Kakuta and Moseushi Formations with designation of each lectostratotipes, and examined the sedimentation period of those formations on the basis of marker tephras. As a result, the sedimentation period of the Kakuta and Moseushi Formations understood about 120 to 45Ka and 42-40Ka respectively. Paleoenvironmental changes in this area are estimated as follows; The Higashi-Chitose Formation Period (about 130 to 120Ka): Alluvial fan is formed by "Paleo-Yubari-gawa River" which flowed into the Pacific Ocean. The Kakuta Formation Period (about 120 to 45Ka): The moor spread with warming by degrees in this period. Then, the moor changed into land by degrees from the south area, and the whole area become land until about 45ka. The Moseushi Formation Period (42-40Ka): Because a huge pumice flow, Spfl, happened in 42-40Ka, "Paleo-Ishikari-gawa River", which flowed into the Pacific Ocean through Ebetsu to Tomakomai in the Ishikari Low Land by that time, was dammed up by the Spfl in north side of Spfl flowed area. As a result, in the Moseushi Low Land, water level rose to 60m above the sea level, and the mud with pumice, which fitted around the Low Land, were deposited. This "Paleo-Ishikari-gawa dam lake" and the back marsh spread in Nopporo. Then a channel was cut open toward Sapporo. The dam disappeared, and fluvial deposits with a lot of pumice pebble derived from Spfal were transported in a moment for the Sapporo area. Thereafter the Ishikari-gawa River has begun to flow into the Japan Sea.

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Late Cretaceous to Paleogene felsic volcanic rocks, which are correlated to the Nohi Rhyolites and allied rocks of the Inner Zone of Southwest Japan, are distributed in the northern part of the Ashio Mountains, Tochigi Prefecture. The volcanic mass that presents the largest exposure among these volcanic rocks in this area has been named as the Irohazaka Welded Tuffs distributed in the south of the Lake Chuzenji. On the basis of detailed field and microscopic observations, the Irohazaka Welded Tuffs is divided into seven pyroclastic units and three volcanic stages. Based on the petrochemical characteristics, it is concluded that the magma of erupted welded tuffs formed the zoned magma in three times indicating an upward increase in the felsic components within the magma chamber. The formative states surrounding the magma are estimated from magnetic susceptibility value to be oxidation state in the early stage and reduction state in the middle to late stage. Furthermore, based on the calculated Sr isotopic initial ratio of 0.71173±0.00028 obtained from the Stage II, it is suggested that the formation of the magma erupted during the Stage II suffered a contamination process between source materials and basement rocks before eruption to the surface. In addition, noticing the similarities in the magma mechanism between the Irohazaka Welded Tuffs and large felsic pyroclastic flows in Yellowstone and Taupo, it is inferred that the magma of main pyroclastic units of the Irohazaka Welded Tuffs was formed under a calm environment with a slow speed of crustal strain in a prominent tensional stress field. On the basis of petrological characteristics, volcanic activities of the Irohazaka Welded Tuffs are correlated to the igneous activites of ilmenite series belonging to the Magmatism Stage III (Harayama et al. 1985) corresponding to the Kasagatake Rhyolites and Ohamamiyama Group of the Inner Zone of Southwest Japan in the Chubu district.

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Recent fieldwork in the west part of Kobe City, Hyogo Prefecture, Japan resulted in the new discovery of augite-bearing mafic tuffs from the middle part of the Shirakawa Formation of the Kobe Group. A large amount of rhyolitic tuff has been well known except for three beds of mafic tuff in the Kobe Group. In the research area, the beds can be traced as a unit composed of three thin beds of ashfall origin with thickness of 15-16, 5-6 and 2-3cm and overly on paleosol. Each layer, furthermore, contains mineral fragments of augite and calcic plagioclase (An64-91). Its color is olive green and its fission-track age is determined as 32.8±2.0Ma. As a conclusion, these tuffs can be regarded as the most useful key bed in the Shirakawa Formation.

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The Nakanotake metagabbroic mass had been considered to be a massive rock body whose interior structure had not been affected by tectonic events. Our study, however, found three schist layers which had undergone remarkable ductile shear deformation from the Nakanotake metagabbroic mass. This fact implies that the Nakanotake metagabbroic mass is made of piling tectonic slices bounded by some schist layers as a ductile shear zone. The pelitic schist layers appear to be conjunctive zones, resulted from a concentration of tectonic strain of piling tectonic slices, because minor deformed structures such as intrafolial and sheath folds developed only in the pelitic schist. In the Katashina Belt, the piling tectonic slice structure has not been found, but the discovery of such a structure would suggest that the Katashina Belt may consist of some piling tectonic slices thrust over the Ashio Belt.

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Kodera et al. (2001) reported the discovery of human remains from the outcrop of the Tako Shell-bed in the Shimosa group, and it is indicated that this fossil human materials belong to the paleolith age. It became clear afterwards investigations, however, that the stratum in which the fossil human material were excavated are not the Tako Shell-bed but the filling sediment of horizontal hollow tomb dug in the precipice of the Tako Shell-bed. This paper examined in the age by the 14C method on fossil human material sample got in the investigation in August, 2001. The fossil human material for the measurement is left metatarsus (TH-89). The sample conducted the pretreatment with Kondo et al. (1992) and Matsu'ura and Kondo (2001). Then, the analysis in 14C's of extracted gelatinization collagen was asked in Beta Analytic Inc., USA. As the result, the chronological value of this fossil human material was 1490±40 yr BP (Beta-160569). It was almost correspondent to an advanced stage from the later stage in the ancient tomb age in the calibration calendar year generation of fossil human material converted from 14C chronological value.

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