GEOLOGIC STRUCTURE OF THE RIUKIU CURVE. 47 



süatli-easterii corner. Inclination is variable, but generally towards 

 the east or south. Beginning from the northern end of the Tertiary 

 region I have found the following beddings: — N-S, El0°-20'' ; then 

 lNr20°-50° E, 8E 10°-25° ; and lastly E-W, S 5°. An exceptional dip 

 towards the north-east is sometimes found in small exposure, but 

 there are no westward ones. 



The Tertian/ of Iriomote-jima. This island, which is principally 

 composed of Tertiary rocks, has the Palaeozoic only on the north- 

 eastern corner, besides scattered exposures of the ancient fringing 

 reefs. The Tertiary rocks are rather regularly inclined and are never 

 horizontal ; they are mostly fine-grained, bluish or brownish sand- 

 stones, the Latter of which often shows a false bedding. Shale is some- 

 times intercalated in these rocks. Coarse-grained brownish sandstone 

 and conglomerate are less developed. Several coal-seams are found in 

 the western part, each dipping towards the west, and with a strike 

 nearly N N E. 



The uppermost bed of the Tertiary, which is exposed near the 

 western coast, is a calcareous sandstone with fossil shells. The 

 exposures are found on the western corner of Hoka- (Soto-) banare 

 and the point projecting between Urauchi-zaki and Unari-zaki. The 

 fine-grained brownish sandstone is found between the calcareous 

 sandstone and the first or uppermost coal-seum, and has the strike 

 X 30°-50° E and the dip N" W 8°-l(r, as measured in Uchi-banare. 

 This first coal-seam, which is only 10 inches thick, is exposed on a 

 curved line running from the south-eastern corner of Hoka-banare 

 toward Uchi-banare. The second seam is the greatest having a 

 thickness of 3 — 4.5 ft. in Uchi-banare, and of 1 ft. on the north of 

 Hoshidate and on the south of Unari-zaki. Between the first and 

 second seams there is fine-grained brownish sandstone with a little 

 shale. In Uchi-banare, the Tertiary rocks show the strike N 45^-60° E 



