>74 



Y. OINOUYE 



This is the normal order of eruptions for all the craters. The ashes 

 and bombs ejected from the fissures upon the sides of the crevice, 

 after a day, or at most a few weeks, built up a cone. The rapidity 

 with which the cones were built depended on the size of the orifice 

 and the amount of ejectamenta. The angle of slope of the cones 

 ranged from 15 to 30 degrees, the steeper ones being made 

 of the rather coarse material. As the cones grew, the old vents 

 became quiescent and new ones broke out . on the side of the 





Fig. 18. — "Puff cones" on the mud-flow. Taken August 19, 1911 



cone, and the ejectamenta, filling the old crater, sometimes 

 obliterated it. 



The life-history of the different cones was not the same, some 

 of them becoming quiescent after only one explosion, others con- 

 tinuing for several days to roar and emit black smoke and to 

 build cones. Some of them emitted smoke intermittently, being 

 active for a few days and then quiet for a few days and then active 

 again, etc. Besides the smoke, ashes, sand, and bombs, a large 

 amount of mud 1 flowed from five of the craters. 



1 Jour. Geol., XXIV, No. 6. 



