12 . AKT. 2— S. YOSUIVVAKA: 



Yü-bari;ire, Eiiiya-banare, Kerama-jima and Hashiya-jinia, and also 

 Kikaiga-sliiin:i, Tokiino-shima, Okinoenibu-jima and Yoron-jima. 



Oshiiim and its Dependent Islets. Oshima, one of the largest islands 

 in the Riukiu Carve, has a great many indentations in its coast which 

 is about two hundred miles in length. The interior is entirely mount- 

 ainous except on the small northern peninsula. There are inhabit- 

 ants only on this flat part and on the small plains at the openings of 

 river valleys. The highest peak, Yuwan-dake is near Yuwan in the 

 southern part and has an elevation of 2300 ft. The northern half of 

 the island is elongated parallel to the trend of its principal hill-range 

 which runs XE to S\V. I>ut in the southern half, the ranges are 

 transverse to the length of the island. There are two remarkable 

 parallel ridges in the western part running eastward, one from Sokkö- 

 zaki, and the other from Edato-jima. They are separated by a very 

 narrow inlet opening toward the west. The island of Kakeroma, on 

 the south of the island of Oshima, is also elongated parallel to these 

 two ranges. The narrow channel between the last two islands is 

 called Oshima-kaikyö or Setouchi. The sea around Oshinui and the 

 adjacent islands is very deep and there are many good anchorages. 



All these islands are almost wholly composed of Palieozoic sedi- 

 ments, with very limited occurrences of old eruptives. liaised coral 

 reefs, Avitli intervening sandy layers, occupy only small areas in the 

 northern corner of Oshima.* The Palaeozoic rocks are chiefly clay 

 slate and sandstone, while slaty sandstone is also common. Tuff- 

 pyroxenite with amphibolite M^as rarely observed in the island of 

 Oshima. Compared with the island of Okinawa, which als(3 

 consists chiefly of Pakeozoic rocks, we find a great resemblance 

 in tectonic and petrography; but in the latter the pyroxenite 



* Yoshiwara, Notes on the Raised Coral Reefs in the Islands of the Riukiu Curve. — Joitrn. 

 Coll. Sei. Imp. Univ., Tokyo, \o\. XVI, Art 1, 1901. 



