s ART. 3.— B. KOTO : 



principal form-casting tectonic disturbance occurred before tho 

 deposition of the Tertiary complex in question. The faulting and 

 other vertical movements, however, took place in the later Tertiary, 

 or early Quaternary period, which movements still continue down 

 to the present, as is evinced by frequenter earthquakes. This 

 geodynamic history is in conformation with that of Central Asia 

 and peripheral China.'^ The volcanic activity of the Kyûkyû 

 chain began concomitantly with the above-mentioned later move- 

 ments after the deposition of the thick lapilli bed, and the for- 

 mation of the trench bay of Kagoshima. It will be referred to 

 again in the sequel (p. 17). 



The volcanic chain, as is frequently the case, traverses 

 indifferently and in the present case obliquely, the ground structure 

 of the Kyûkyû arc, and enters right through the middle of southern 

 Kyûshû, tSakura-jima being one of the vents upon the chain. An 

 inspection of the bathymétrie conditions in Sketch-map Fig. 1, can 

 tell the facts better than the writer. 



Located between the two parallel deeps — the Ryûkyû fore -deep 

 (Graben) and the inner rift- valley (Fig. 1), the Ryûkyû cordillera 

 might have suffered ' framed folding ' (Suess's Rahmen faltung). 

 It is an open question whether the present volcanic chain stands 

 on the margin of ' relaxed ' horst, here meant by the Ryûkyû 

 cordillera, as in Sumatra,'^ or not ; but at the distal end of the 

 chain in southern Kyûshû several well-known volcanoes lie within 

 a negative land-form — of which the trench depression, Kagoshima 

 Bay, gives us unequivocal evidence (Fig. 2). We have to speak 

 about it later on. 



1) Maclaatschek, 'Neuere Arbeiten zur Morphologie von Zentral- Asien.' Geogr. Zeltschr., 

 1914. 



2) Volz, 'Die geomorphologische SteUimg Sumatras.' Geogr. Zeitschr., 15. Jahrg., 1909. 

 S. 11. See also ' Die Gajoländer,' by the same author, Berliïi, 1912. 



