The petrological characters of garnet-bearing thermally metamorphosed rocks from the Nake sate district are treated with the brief description of general thermal metamorphism in the present district. For the purpose to clarify the metamorphic conditions, chemical analyses of metamorphic rocks, biotites and garnets have been carried out. In the present district, garnet is found restricted only in the politic thin layers laminated within highly metamorphosed compact chert, while curdierite appears in the hornfelses of common argillaceous rock origin. There is no difference in MnO-MgO-FeO ratio between the garnet-bearing and garnet-free rocks, while in AKF diagram they show distinct difference in Al_2O_3 content. It may be due to their chemical peculiarity that garnet does not appear in the metamorphic rocks of common argillaceous rock origin.

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During the geologic investigation in 1959, the author fortunately found many conodonts from the Palaeozoic beds at the western part of Ashio mountain. Among them, 18 genera and 7 assemblages are reported in this papaer. This is the first discovery of conodonts in Japan. Though it is said that fossils are generally rare in the Palaeozoic rocks except for the limestone, it becomes clear by the author's discovery that many kinds of conodonts are included in such rocks, as basaltic tuffite, tuffaceous slate and chert. Therefore, conodonts may become the leadingfossils in the formations hitherto remained unfossiliferous.

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The Chichibu mountains situated at about 100km northwest of Tokyo, have been called the birthplace of the Japanese geology, since the geologic survey was carried out by the late B. KOTO who was the first geologist in this country. Therefore, the area comprises the type localities of the Sambagawa crystalline schist, as well as the Chichibu Palaeozoic formations which are widely developed in Japan. In this paper, the authors summarize the geology of this area, based upon the recent knowledge. In the geologic map, the Palaeozoic formations are indicated by the horizontal lines, its metamorphosed facies by the wavy lines, the Mesozoic formations by the vertical lines and the Tertiary by the oblique lines respectively. And the dotted areas resting on the older rocks are the Quaternary or the terrace deposits. The geologic profile is drawn along the line directed northeastwards from Jumonji pass that is the southwestern corner of the geologic map.

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In this paper, the author deals with the Shinshu Loam formations consisting of volcanic ash, pumice, scoria and mud-flows and with the associated some events recorded within the Loam in the Kiso Valley. Moreover, the author disscusses a question whether any tephraic horizon may be used or not as the key for the mutual correlation of river terraces along the Kiso Valley. In the Kiso Valley, the Loam formations are divided into three Loam unit, namely the Younger, the Middle and the Older Loam. The Younger Loam contains two scoria beds, a sheet of mudflows and a yellow pumice bed, and they are usable as the key beds for the correlation of the river terraces. In the middle horizon of the Younger Loam, there is an unconformity which was produced by solifluction under the past cold climate. This unconformity is also useful for the mutual correlation of certain horizons of the Younger Loam. The Middle Loam has three pumice beds, namely "the first", "the second" and "the third pumice bed". Each of these is distinguished by the relative amount and the composition of the heavy minerals contained and usable as key beds. Pumice grains of water-deposition are also useful as the key when they are confirmed to be primary deposits. The Older Loam is situated directly upon the Higher Terraces and in another case embedded within the deposits building the Higher Terraces. This Loam contains one or two pumice beds, but its stratigraphic section is not established clearly.

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[in Japanese]

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