40 ART. 2,— S. YOSHIVVARA : 



their present inclination seems to be due to n pressure exerted long 

 after the eruption of the stock. Therefore the part ( ', though much 

 disturbed in its northern part, still shows the constant dip of the 

 Palteozoic sediments, namely 20° — 40° to S or S\V and the strike from 

 E — AV to X20°W. This strike is apparently transverse to tlie longer 

 axis of Ishigaki-jima. 



The part D lying on the south of (J lias hills of PalaMjzoic sedi- 

 ments surrounded by a plateau of raised reefs which ;nv now almost 

 entirely eroded on the eastern coast. The l*aheozoic consists of 

 pyroxenite or amphibolite with small layers of clay slate and quartzose 

 sandstone. They are very regularly inclined, with no signs of fault- 

 ing or folding. The following measurements luive been made on the 

 rocks of the eastern coast beginning from the north: 



E— W S 30°, E 30° \\' SW 30 \ N 5()'\\ 8W 60\ 



N 50°W SW40°, N 40°\V SW 50\ N 45°W SW 60=, 



On the mainland A, pyroxenite or amphibolite, as well as clay 

 slate and quartzose sandstone are limited to the eastern part, while 

 larcre districts of igfneous rocks and compact quartzite are observed on 

 the west. Pyroxenite is comm<jn. Quartzose sandstone, clay slate, 

 and alternations of chiy slate and quartzite are also not rare. The 

 inclination of these rocks is quite constant. 1 measured, in the north- 

 western part, the strike X40°— 50°W and the dip XE 20^-60=. Even 

 the small coast exposure of Pala30zoic sediments, lying very close to 

 the east of the Xosoko volcano, has the strike X oO°AV and the di]) 

 XEio". Also the southern Paleozoic regions have the strike X20° — 

 70°W and the dip XE 20° — 30°; the most common measurement is 

 X40°\Y, XE25°. Thus the Palaeozoic rocks of A, except the compact 

 quartzite, have dips quite opposite to those of C and D, though the 

 strike remains the same. This is perhaps due t(.) the great andésite 

 eruption of the Xosoko volcano. 



