On the so-called Crystalline Schists of Chichibu. 



(The Sambagawan Series.) 



by 



Dr. Phil. Bundjirö Koto. 



With plates II, III, IY,&V. 



Introduction. 



Tlie district of Chicliiba is in the Main Island (Ilonsiu) of Japan 

 Ivino- to the north-west of oar nietropoHtan city (jf Tokyo within 

 a dnv's march. From considerations geological rather than ])o]incal, 

 Dr. E. Naumann 1) has very appropriately called this region the "alte 

 Bero-land von Kwanlö"— all the mountainous districts surrounding 

 Chichihu proper being comprehended under this designation. The 

 district now under consideration lies to the east of the s«vcalle<l 

 great geologic ditch or '■fossa magna ' of E. Nauinannj^O which inter- 

 sects the Main Island from south-east to north-west through the 

 provinces of Izn, Snriiga, Kai, and Sinano, thus separating Xorthcrn 

 and Southern Japan. The \fossa magna,' or the Japanese mountain- 

 con flexure (Schaarung), as Suess=^) and Harada-^) call it, sends 



1) Ueber den Bau und die Entstehung der japanischen Inseln, Berlin, 1885, p. 79. 



2) loc. cit. p. 50. 



3) E. Naumann, Die Erscheinungen des Erdmagnetismus in ihrer Abhängigkeit vom Bau 

 der Erdrinde, Stuttgart, 1SS7, p. 17. , ^ ,• u 



4.) \ letter from T. Harada read in the ' Sitzung der mathematisch-naturvnssenscLaftlichen 

 Classe vom 7. Juli, 1S87.' Vide 'Akademischer Anzeiger,' No. XVII, Wien. 



