GEOLOGICAL OBSERVATIONS 



and formed a " mushroom." Commonly in these eruptions 

 two columns could be distinguished issuing from the 

 crater, one white (steam), the other brown. When the 

 two columns were soon caught by the wind, the white one 

 went higher, and the dark one remained lower. Several 

 times there were three columns in the crater, and on 

 April 11 there were two in the crater, and one outside, 



Great Steam Eruption, September 8, 1908 



well to the right. This last might be of steam which had 

 rolled out through the gap. 



One of the largest eruptions happened on June 14, 

 when the steam was repeatedly blown up to a great height, 

 and getting into a still region of several thousand feet 

 above the crater, spread out on both sides into a great 

 mushroom cap. At one period, while we were looking 

 at it, a more forcible eruption took place, and the ascend- 

 ing column penetrated the mushroom and formed a cone 

 above it, as shown in the figure. 



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