EARTHQUAKE OF CENTRAL JAPAN, 1891. p)()7 



showing gneissose structure, t;ikes up large geological blocks or 

 " ScliolJcH " of gneiss, gneiss-mica schist, mica-schist and also am- 

 phil)ole-schist, which may l)e classified into Laurentian, and Fp])er 

 Archaean (tlie Takanuki and the (lozaislio series). The writer has 1)een 

 recently engaged in a special study of tliesf antnent rocks, and the 

 results will l)e found in earlier pages of this voliune. 



Thus the twin ])rovinces are on three sides bounded by masses of 

 mountains, and in their very centre lies an extensive populous plain, 

 Avith an area of not less than 1,051 square kilometres or 68 square 

 ri. The general as])ec.t of tlie plain, which inclines slightly towards the 

 foot of the Yöi'ö ridge is monotonous and flat. It is covered with 

 a net-work of rivers and artificial canaJs which, owing to the special 

 orographic condition c^f the low-lying tract, mostly concentre at the 

 western margin (see Map, PL XXTX.). The largest of the rivers is 

 the Kiso-gaw^a, which starting from the dense impenetrable forest of 

 the Kiso-kaidö, is fed by several tributaries before entering the 

 plain, wdiere it joins with the Nagara and Tbi. These confluent 

 streams branch off at one point and reunite at another, discharging 

 their waters at the head of the IJav of Tse. near the port of Yokkaichi. 



The head-w^aters of the Kiso drain the granitic area, of the 

 ]H'imeval forest of Shinano, and the swift current, carrying with it an 

 enormous amount of detritus and sand, unloads its contents in its 

 lower course. The formation of the ])]ain is, I think, largely due to 

 the sediments of this river. The lowland of Mino and ()wari is usually 

 spoken of as having been once an immense swamp, since converted 

 to the present paddy-l;nid within historical finies, and having as the 

 last remnant of its former grandeur the Lake of Shim(i-ike, at the foot of 

 Yörö. [t now stands foremost in I'ank among all the rice-])roducing 

 districts of Ja[)an, and supports hun<lreds of thousands of people, 

 Nagoya, Gifu, and Ogaki being the chief centres of its commen/e. 



