108 ART. 3. — B. KOTO : 



From tlie Table given the area of the western lava- field is 

 7.202 sq. km. with a corresponding volume of 0.2881 cub. km. ; that 

 of the eastern is 11.139 sq. km. inclusive of submarine flows, and the 

 volume 0.8529 cub. km. As the density of the Nabé-yama lava is 

 Whole 2.64, the wholc mass of lava poured out both from the 



Lava castem and western vents amounts to 3,012,240 million 



kilogrammes or 3,012 million tons. The volume of juvenile lava is 

 equivalent to 1/14 of that of Sakura-jima, the latter being 

 15.949 cub. km. (p. 32). Assuming that recent and ancient lavas 

 have the same density, the relative proportion of the mass of new 

 lava to that of the preexisting is also 1 : 14. 



On his trip to Sakura-jima in April 1915, F. Omori took a 

 remarkable photographic view of the lava -flow on the Nabé-yama 

 side (PI. XII. Figs. 1 and 2). This is a secondary lava-stream pressed 

 up fi"om below the still unconsolidated portion of the extensive 

 lava -field of the preceding year. The still molten mass inside 

 l)urst open through the outer hardened crust and crawled downwards 

 from the middle of the field over its gray ash- coated solid sheet 

 toward the lava-precipice. From this point or ' head ' it rushed 

 down anew into the sea (black fresh lower area in Fig. 1), 

 taking a divergent course at its front. 



The land so newly reclaimed pyrogen etically is, geomorpho- 

 logically speaking, a kind of delta which may be likened to the 

 ' bird-foot delta of the Mississippi.'' See PL XII. Fig. 1. The digiti- 

 form field has ramifying axial channels (black lines in tlie picture), 

 comparable with the diverging ' passes ' of the great American 

 river. While the upper and under portions had solidified and were 

 creeping sluggishly onwards, the still molten portion was able to 

 move faster and thus to leave empty spaces behind it. The steam 



