THE ERUPTION OF BANDAI-SAX. 141 



is a distant view of the mountain from a photograph taken by Prof. 

 W. K. Burton, nearly a week after the eruption, showing the linear 

 arrangement of the steam-fissures. It was alon» this line that the 

 eruptive power of steam rent Ko-bandai into pieces. 



It is manifest that the immediate cause of the eruption was the 

 sudden expansion of steam pent up within the mountain. Of lava 

 or pumice there is no trace. The grey coloured ashes which form a 

 chief product of the explosion are evidently the powder of pre-existing 

 rocks decomposed by the action of fumaroles, and have not been deriv- 

 ed from fused magma. 



The character of the explosion was thus comparatively simple, 

 being to all appearance a sudden shattering of part of the mountain 

 flank. The work of the explosion has been practically to tear off a 

 portion of the side-wall of the old crater. 



It has often been observed that the first action of some volcanic 

 outbursts is characterized by extreme violence, large masses of super- 

 incumbent materials which have accumulated in the crater being 

 thrown out, or the side- wall being blown away, by the expansive force 

 of steam. This first stage of the eruption is usually followed by minor 

 ones accompanied either by lava flows or pumice ejections. Thus 

 the finer particles or ashes ascending into the air are different in 

 character in the successive outbursts; those which are ejected dur- 

 ing the first stage of the eruption consisting largely of fragmentary 

 materials, while those of the later eruptions are found to be more or 

 less pumiceous, a fact showing that the latter are derived from the 

 fused matter. The explosion of Bandai, characterized by its sud- 

 denness and violence, and effected in a very short time, may be likened 

 to the first stage of eruption. But no subsequent discharge took 

 place, nor were any signs of farther disturbance discernible. 



We have already indicated that the volcanoes in the vicinity of 



