20 ART. 3. — E. KOTü : 



their orifices only on the edge of a rift-valley, ichen iJie depressed 

 and compressed crust makes uudertlirust against the stand'mg block, 

 which in consequence rises and expands and also hursts open, therehij 

 giving occasion io the escape of magma. 



In the present area, the undisturbed plateau simply sank 

 down clear-cut in trench form, the bottom of which w^as, how- 

 ever, multifariously shattered into polygonal blocks, which appear 

 above the water of the bay as the islets of Oko-shima, Hakama- 

 goshi, Ko-jima, Kanzé, and Karasu-jima, the last being buried 

 under the recent lava-flows. Simple fragmentation is directly 

 opposed to the compacting of the wedged-in crust. This may 

 afford some opportunity to the upward stoping and the eruption of 

 active magma. Volcanoes make their ai^pearance in a diffuse 

 manner in such a pattern of great magnitude. In another aspect 

 it seems to accord well with Reck' s second case^^ of the occurrence 

 of eruptive vents, that is to say, within a trench valley the out- 

 bursts follow the fracture-hue which bounds the table-horsts. 



In short, the plateau of Satsuina and Osuinl is a table-bloch, 

 while the table-fracture tcithin the block creaied Kagoshima Bay, and 

 the fragmentation of dropped block gave occasion for the escape of 

 magma to the surface. 



B) The Outlying Ösumi Group-)— Tlie extensive plateau-land 

 of lapilli is not confined to the above area. It occurs not only in 

 detached patches in central- western Kyùshû, but also on the 

 southern extension of Osumi and Satsuma in the form of inland 

 groups, where it occupies a total area more than that already 

 mentioned. The writer adduced the facts of this unexpected dis- 



1) Wolff, 'Der Vuliiiuismus,' I. S. 111. 



2) See ante, p. 5. 



