lient points, the highest Ijeing the Youiogitii-yaiiia (DHo /;/.), with 

 al)rupt Ijlnifs along' main (h'ainage-ehannels, ii.su;illy in an east a.nd 

 west course. Tlie hilly tahle-land faces the Pacific sea-l)î)ar(l, as al- 

 ready iiieiitioned, with a, steep escarpment five to six hundred 

 niöters down to the plain below. On the west the slops is scarcely 

 perceptible, and the plateau merges gradually in the fertile valley 

 of the Abukunia river ; only in a few places is the fall very marked. 



The field of my study does not comprise the entire plateau, but 

 is chiefly confined to that portion between the cities of Taira and 

 Tanagnru (Plate XXll). As the strutigraphy of the Arcluean for- 

 mation of this country has not hitlierto been systematically worked 

 out, it was my desire to know^ sometliing of the sequence of super- 

 position of the schistose series ; and this point I have always 

 had in mind during my trips. On the other hand, 1 cared but little 

 about the topical distril)uti(,)n of s[)ecial grou])s of rocks and tlieir 

 recipr(jcal iKjundaries, ]ea\ing these details to the mapping geologist, 

 Mr. Orsuka, who is now prosecuting the field-work of this region. 



III. Archaean Geology. 



General Statement. 



The xlrcluean rocks of the Abukunia plateau, like those of other 

 parts of the W(jrld, are separable [)rimarily into two main di\i- 

 sions, viz.: an upper, chiefly schistose, bedded ; and a lower, of the 

 granitic, dioritic, or syenitic type of iniiieralogic.d composition, but 

 more or less gneissose in structure. In the (a) upper divisi«3n there 

 can be recognized at least two leading groups. One of these is de- 

 veloped in full advantage (3ii the way from T'aira to Takanuki, 

 throuuii the nariNjw u'oro'es of Gozaisho. The otlier is found in its 

 typical foi-ni in tlie region lying to the west of tlie f naner, and occurs 



