GEOLOGIC STRUCTURE OF THE RIUKIU CURVE. 



II. THE TOKARA GROUP. 



This gToup lying on the north-west of Oshima, consists of very 

 suuill islands on a line NE to SW ; viz, Yoko-shima, Kaminone-sho, 

 Tokara-jima, Shimako-jima, Akuseki-jima, Siiwanose-jima, N"akano- 

 shima, Kiichino-shima, Taira-jima, Gwaja-jima and Kogwaja-jima. 

 According; to Mr. Yaniao^ami, all these islands consist of andésite. 

 Solfataras are said to exist on Xakano-shima, Kogwaja-jima and Aku- 

 seki-jima. He also informs me that Sawanose-jima is even now 

 sending- forth lava and is considered as the onlv active volcano in the 

 Riukiu Carve. Besides, distinct volcanic craters are seen in Nakano- 

 shima and Akuseki-jima, and some traces of volcanic centres in 

 Kuchino-shima and Gwaja-jima. 



III. THE ÖSUMI GROUP. 



This group contains only a few scattered islands near Kyûshû. 

 The two largest islands, Tanega-shima and Yaku-shima, have already 

 been described by Mr. Nishiwada.* According to him, Tanega-shima 

 has the shape of a battery with the highest peak 1200 ft. above the 

 sea-level, and consists of Tertiîiry rocks, such as sandstone, shale and 

 conglomerate, with thin layers of impure limestone and brown coal- 

 seams. The strata are greatly distorted with a strike NNE, which is 

 parallel to the longer jixis of the island. Diluvial rocks cover the 

 Tertiary, but here the raised coral reefs, which are met with in the 

 islands lying to the south, are never found. According to Mr. E. 

 Sao-awa, who visited this island in 1899, the interior seems to be 

 composed of two different formations. The older one is greatly 



* ^^ ^JScMX^^^s^ (Report ou Taue^a-shima and Yaku-shima; in J(tp'nie>!e).— Tlie 

 Journal of Gcographj , Tokyo, Vol. YII, No. 80, 1895. 



