GEOLOGIC STRUCTURE OF 'J'HE RTUKIU CURVE. ßl 



r) Daikükö-iwözan (sandstone): Madia sp., Area sp., Coral. 

 In the southern half of the island I have found a tectonic different 

 from that in the northern half. In the eastern part of the former we 

 lind a shale with a little sandstone as at the southern foot of Sörei. 

 Then toward Taikeishö, the rock is found to be chiefly bluish shale 

 with nodules. Thence to Köfunshö, it show^s a fracture with spindle- 

 shaped fragments. Ijluish shale, with a few layers of quartzose 

 sandstone and hard sandstone, is then exposed on the south of Köfun- 

 shö. In this shale, whose exposures on the north of Giran have been 

 described by Mr. Ishii as " Mesozoic slate," I have collected TelUna 

 and Schizaster at Fukutokkö. The latter is a form found in all rocks 

 from Tertiary to Recent. Thus the boundary between the Tertiary 

 and older rocks must l^e found to the south of lliran. 



The o-eoloo-v of Xorth Formosa shows a connection with that of 

 the Saki-shima group. (1) Many coal-seams of the same character are 

 common to both. Though they are less in number and thickness in 

 Iriomote-jima (Saki-shima group), yet they are all found in the same 

 iine-grained brownish sandstone in Formosa as well as in Saki-shima. 

 Yonaguni-jima lying betw^een Formosa and Iriomote-jima, as well as 

 Miyako-jima, have traces of the same coal-seams. (2) Though fossils 

 are rather scanty in both regions, I found in Formosa and Iriomote- 

 jima, the characteristic Echinodicus and Jstnchjpcus in a rock lying 

 between the coal-seams. The Echinoid found close to the coal-seams 

 in Yonaguni-jima is probably of the same species. (3) The typical 

 species of Pecten occurring Avith Echinodiscus in Formosa, is also 

 abundantly found in Miyako-jima. (-1) The Tertiary of Formosa has 

 the strike E-W, thus the strata running towards the Saki-shima 

 group, whose western part is opposite to Formosa, are entirely 

 Tertiary. 



The Echinodiscu.s is a form found from Miocene to Recent, and 



