GEOLOGY OF JAPAN 57 



Apart from these two zones, Honshu or the ]\laiu Island is divi- 

 sible into two parts, ''North Japan" and "South Japan", by the 

 "Fuji Volcanic Zone" Avhich runs across the middle of the island 

 from the Pacific Ocean to the Sea of JajJan. This volcanic zone 

 represents a great ruptured tract of the land, whore the great cone 

 of Fuji, together with several others like Hakone, Yatsugatake, Myoko, 

 etc. were built up. 



The sedimentary formations and contemporaneous igneous rocks 

 occurring in Japan may be shown in chronological order as in the 

 annexed table (p. b^'). 



2. Sedimentary Formations. 

 (a) Palaeozoic Group. 



The Palaeozoic Group may be divided into 



(1) Pre-Carboniferous System. 



(2) Carboniferous and Permian System. 



(3) Ryoke Metamorphics. 



(1) Pre-Caeboniferous System. 



The rocks of this system consist of the crystalline schists of 

 various kinds in the lower horizon, while in the up[)er, they are 

 pyroxenite or amphibolites with phyllites, intercalating limestone and 

 quartzite layers. The age of these rocks has not yet been determined 

 with certainty, but, as they are usually conformable with the over- 

 lying Carboniferous strata., they are X'l'o^'isionally included in the 

 Palaeozoic. According to Dr. B. Koto, the sj^stem is divided into two 

 Series : 



(A) Sambagawan Series (crystalline schists) 



(B) Mikabu Series (pyroxenite, phyllite, etc.) 



(A) Sambagawan Series : This comprises various schists of a phyl- 

 litic or highly schistose aspect with the characteristic components such as 

 sericite, chlorite, epidote, glaucophane, piedmontite, etc., but almost 

 free from biotite. They are accompanied by eruptives such as serpen- 

 tine, gabbro and garnet-amphibolite, but not by granite. Although 

 the rocks of the Sambagawan are easily discriminable from those of 

 the Eyoke Metamorphics, the distinction between the Sambagawan and 



