110 B. KOTO 



B. Architectonics of the Sambagawan Series 

 of the Chichibu district. 



(e) General Remarks. 



The writer has; been so far wholly engaged in describing at some 

 leno'th the objective representation of all the rock-varieties which 

 constitute what is called the Sambagawan series ; he now turns 

 to another topic — the geotectonic condition of these schists. 



The Sambagawan complex forms the very lowest of the long 

 geologic series, that makes its appearance in the Chichibu district, so 

 far as the present state of our knowledge permits us to say. 

 From the analogy of other occurrences, especially in the Island of 

 Sikoku, where thanks to the munificence of our Geological Survey, 

 the writer was placed in a position, last year, to be able to geologize 

 the countries traveled through, and of which he hopes to give some 

 account on another occasion as a continuation of the present study, 

 it is highly probable (but by no means proved) that this series is 

 superposed upon a complex of biotite- mica-schist and biotite-gneiss 

 with great unconformabilities, which indicate a long lapse of time 

 between the formation of the two series. ^^ 



1) The above supposition has been, to a certain extent, confii-med during a trip this winter 

 (1887-8) to the provinces of Mikawa and Tötömi, where coarse-lameller hiotite -schist, 

 gray, streaked gneiss and then dark-gray, fine-lamellar viica-scliist with the intercalated 

 quartz-schist, in all of a considerable thickness, are developed to their full advantage. These 

 typical Archaean rocks, which the writer saw for the first time in this country, form a long 

 belt, beginning from the interior of Sinano, along the upper course of the Tenriû river, 

 through the province of Mikawa, terminating at the Bay of Atsumi. 



The general direction of this long, curved belt, with the convex side toward the south-east, 

 is N.E. — S.W. ; and this belt represents the western wing of the Japan—" Schaarung " of Suess 

 (Naumann» Die Erscheinungen des Erdmagnetismus, etc., p. 17.). Parallel to the curvature 



