GEOLOGIC STRUCTURE OF THE R1UKIÜ CURVE. 45 



separated from the limestone by Alluvial sand and raised reefs. The 

 entire region of the cape î»^obara-zaki is of Tertiär}^ rocks showing the 

 following order of superposition : — 



Bluish sandstone. 

 Tnff without andésite blocks. 

 Agglomerate-tutf with andésite blocks. 

 Brownish tnfaceous sandstone. 



All the rocks Ivinir on the northern and eastern sides (jf this 

 andésite hill show the dip varying from S AV 25° to S 30°, with the 

 strike from N 60° W to E-W. Even at the line of contact with the 

 andésite, there is no marked disturbance of bedding. (Jn the south, 

 limestone exposures along the (-oast are separated from these 

 exposures by a narrow stripe of Alluvial sand. The limestone shows a 

 regular southward dip with an angle of 20", and consists almost 

 entirely of tlie calcareous algie, identical with Liihoihamniwn rosenbergii 

 Martin* from the miocène of TinK^]'. ])esides these only one large 

 Irregular Echinoid belonging to the Spatanginae has been collected. 

 The limestone extends more than a thousand feet along the shore, 

 and is covered at its southern extremity by sandstone containing 

 pebbles of Pala30zoic sediments. In the neighborhood of Karadake 

 on the west of Tözato and Moriyama, there is a small exposure of 

 sandstone with ])ebbles of Pakeozoic sediments. It shows a dip 

 31^ south as in the other parts of Ishigaki-jima. I'hick beds of 

 limestone, with the same apjjearance and fossil contents as those above 

 mentioned, are on the north of Miyara-mura. I found here two thin 

 intervening layers of the pebbly sandstone, which, as in other places 

 in the island, show the dip 2ô°-30° SW and the strike X 50° W. 

 Sometimes the Tertiary rocks are, in dire«:;t contact with andésite, 



* Martin, Die versteinerungsfiihrenclen Sedimente Timor's. Sainni. (ha (rcol. Heichu — 

 Museums in Leiden, T Serie, I Band, 1881. 



