112 B. KOTO 



mountains of Japan. According to the statements of E. Naumann,^) 

 the chief granitic eruption occurred at the end of the Palaeozoic, 

 or at the beginning of the Mesozoic era in the Japanese Islands ; it 

 seems, however, not unreasonable to suppose that the granites in 

 our country are not the product of a single eruption. 



The Sambagawan series has been, perhaps, formed after the 

 first eruption of granite. And the post-granitic schists included in 

 the above-mentioned series are of a considerable thickness probably 

 not less than 300 m. ; and these schists in turn have been overlaid 

 discordantly by an equally thick complex of the epidote-pyroxenite, 

 pyroxene-amphibolite, and epidote-amphibolite which the ^Yriter is 

 rather inclined to consider as various modifications of the tuff's formed in 

 some way in connection with the eruptions of gabbro, cliorite and 

 diabase. 



The rocks of eruptive origin just referred to can be seen typically 

 developed around the conical-shaped Mikabu peaks, and accordingly the 

 writer designates provisionally the whole complex of gabbro, diabase, 

 the gabbro-diorite, and their derivatives under the name of the Mihibu 

 series. The pyroxenites^) and amphibolites of the above series, usually 

 spoken of simply : s chlorite-schists by our geologists, claim our special 

 attention, as they contain an interesting mineral — the secondary 

 glaucophane of which discriptions have been lately given by the author 



1) Loc. cit. p. 40. 



2) These pyroxenites and amphibolites with their nuuiberlcss varieties play a not insig- 

 nificant part in the geologic terrane in Japan, and they have justly full claim to special 

 treatment and independent cartographic representation. To the writer, the above-named 

 rocks seem to b3 the altered crystal-tuff (in contradistinction to the agglomerate-tuff), 

 originallycomposedsolely of (excepting some few cases) one mineral— the pyroxene which had 

 been thrown up from eruptive vents, just as in the case of ejectamenta of modern volcanoes, 

 and then deposited at the bottom of the once Uinrcrsul ocean of the past, when dry land was 

 comparatively rare. In order to avoid a confusion of the nomenclature, designating rocks of 

 quite unlike origin, or conveying different meanings about the genesis of this class of green, 

 schistose r.~cks, to which are attached diverse views sometimes diametrically opposite, the 

 writer thinks it advantageous to apply the names of clunto-jiijro.roiitc and rldstd-iniipliibolite 

 respectively to our rocks, thereby signifying their tufaceous origin, just as Lossen had done 

 long ago for the kindred variety of quartzporphyries. Zeitschrift d. deutschen Geol. 

 Gessel. XXI. 1869. 



