172 AKT. 3. — B. KOTÔ : 



crysts are as usual very scarce, but augite predominates over 

 hypersthene. Excellent micronoritic segregations are typically 

 developed in this lava, as in Text-fig. 36. 



D. The An-ei Lava of 1779 to 1781. 



(Southwest and Noetheast Sides.) 

 PL XVIII. Figs. 6-8, PL XIX. Figs. 1-2. 



a) Mode of Occurrence. — After a lapse of thirty years from the 

 slight eruption of Ohira-yama in 1749,^^ the most terrific paroxysm 

 ever recorded of Sakura-jima happened in the An-ei era, especially 

 from 1779 to 1781. This An-ei eruption has left a more dreadful 

 impression than that of the Bummei era from 1471 to 1476.'^ 



Like the preceding activity, the An-ei eruption occurred also 

 bilaterally in the same orientation, i.e., on the southwest on one 

 side and on the northeast on the other, as may be seen on 

 Geologic Map. The vents of the former period lie at a compara- 

 tively low elevation of 400 m. in the Byobu-hira area, while those 

 on the opposite side at Urano-mayé are probably hidden by later 

 flows, the vents exposed to view being only at about 200 ??z. above 

 sea-level. 



In contrast to the former, the vents of 1779 lie far up at an 

 altitude of 700 m. on both sides, corresponding to the greater amount 

 of energy exerted in the volcanic manifestation tha7i in that of the 

 Bummei era. 



Although the eruptions were active on botli slopes, as has 

 been already stated, the lava emission on the south (the large 

 vent of An-ei- San, PL XI. Fig. 3) is comparatively insignificant. 



1) See page 170. 



2) See page 163. 



