THE ERUPTION OP BAXDAI-SAX. Ill 



are the quantities of small cones, varying from a few metres np to 15 

 metres in height, which are scattered here and there over the surface, 

 standing out of the débris like so many miniature Fujiyama». Fig. 1, 

 PL XXI. and PI. XXII will give some idea of these objects, as seen 

 respectively from the northern and eastern side of Bandai. When 

 closely examined, they are found to be disintegrated crumbling rocks, 

 so aftected by the agency of heated steam and corroding gases as to 

 have lost their compactness. They are similar in character to the 

 disintegrated rock commonly found near the crater- walls of active 

 volcanoes. During and after their swift descent down the mountain 

 sides, these rock masses have crumbled away, and the debris, falling 

 around their bases, has assumed a conical shape by forming ialuses 

 around them. Fig. 2, PI. XVIII, is a representation of one of the 

 smaller of these hills found near the former site of the Kawakami spa. 



On reaching the outposts of the mud field, no one could help 

 beino- struck by the singular way in which the advancing" stream of 

 rock and earth seemed to have suddenly stopped, showing a vertical or 

 nearly vertical face, a few metres high. It is apparent that the debris 

 of rock and earth in their swift descent behaved like a fluid, but on 

 nearing to the plain below they gradually lost speed and were ul- 

 timately brought to rest; the materials that followed, on account of 

 their great friction and adhesion could not pass the limit set by their 

 predecessors, and were piled layer on layer, thus forming a steep edge. 



As is usual in all volcanic outbursts, large quantities of greyish- v ] can i c dust 

 blue dust, or so-called ashes, fell during the eruption in the form of 

 showers. Evidently much of this dust was produced by the mechanical 

 trituration, during their flight through the air, of the rocks ejected by 

 the explosions, which rocks, as already explained, had been rendered 

 highly friable by the action of steam and gases. We found, in fact, 

 that the dust was allied in character to the pulverulent matters com- 



