118 B KOTO 



2. — Along the Arakawa from Yorii to Hon-iiogami, illu.strative 

 examples of the alternation of the spotted black, and green schists are 

 exposed to view with moderate dips variable at times but generally 

 to N.E. 



3. — In the other localities, such as, on the road from Kodama to 

 Oda, in the environs of Onisi, in the lower course of the Sambagawa, 

 in the Hino valley beginning from Kanai to Kami-Ilino, or, lastly, 

 in the Akihata valley, these two rocks always occur in multifarious 

 alternations, the higher portion of which consists chiefly of the 

 graphite-schist. The dip is usually very gradual, the prevailing 

 strike harmonizing well with the general axis of the whole series, 

 and it is not imcommon to find them in a perfectly horizontal 

 position in extensive tables. 



(h) The Upper Sambagawan. 



The upper division is mainly confined to the southern side of the 

 Arakawa and makes its appearance on the higher parts of the hills. 

 This light-gray or dark coloured rock is nothing but the epidote- 

 sericite-gneiss which in the lower horizon is thick-platy, while on the 

 higher zone it becomes a very thin, papery schist. The latter shows 

 on the cleaved surface a silky lustre, and through long exposure to 

 air the rock falls into a soft, talcose, glittering, slippery mass. 



The writer has always been confronted with difficulty in 

 assigning the boundary of this and the preceding division, as the 

 spotted graphite- schist of the Middle Sambagawan insensibly blends 

 with that of the Upper Sambagawan forming with it a continuous 

 series. Between the Lower and Middle divisions a well-characterized, 

 red piedmontite-schist serves well for the purpose ; while here such 

 reliable means fail entirely. Consequently the writer in this case 

 stands ratlier on weak footirjg in establishing the separate existence 

 of the Upper Sambagawan. Nevertheless, the writer believes he is 



