THE NATIONAL GEOGRAPHIC MAGAZINE 



143 



cannot fail to wonder how they could 

 have reached their present position. Ly- 

 ing, as they do, on top of the ash, they 

 evidently have been deposited there since 

 the eruption. As one looks around for 

 a source, he is strongly inclined to sus- 

 pect that these immense chunks w r ere 

 shot out from the mountain directly to 

 their present position, without a prelimi- 

 nary roll down hill, which surely would 

 have dissipated the fragments and have 

 left a tremendous furrow behind, where 

 they rolled across the soft mud in which 

 they lie. 



As one approaches closer to the foot 

 of the mountain he sees other evidence 

 which adds weight to this hypothesis. 

 Along the base of the mountain is a deep, 

 wide fissure, that would stop any of the 

 rolling stones, which, indeed, seldom 

 reach it. But beyond this fissure are 

 many rock fragments of all sizes. Among 

 these are also found the marks where 

 they struck, deep cuts into the ground. 

 Some of these are quite fresh, so that as 

 one walks among them he watches the 

 precipice above apprehensively, with a 

 view of dodging any missile which may 

 come his way. 



STEAM ISSUES EROM SOLID ROCK 



Some of these pieces are still solid 

 rock, but others have completely disin- 

 tegrated into small fragments since their 

 discharge from the mountain. The ap- 

 pearance of these fragmented rocks is 

 very similar to that of rocks which have 

 spawled under great heat or broken up 

 after the repeated effects of freezing and 

 thawing, but the disintegration is very 

 much more complete here than one sees 

 in such cases. These rocks look, there- 

 fore, as if they had been broken up by 

 forces within themselves. 



When one has made this observation 

 he looks with renewed interest on the 

 steam escaping from the solid rock above 

 and turns to the large piles from some 

 of which steam is still escaping in con- 

 siderable volume (see page 136). An ex- 

 amination seems to indicate that the 

 steam comes from within the piles them- 

 selves, rather than from the ground be- 

 neath ; but most of these are so covered 

 with loose fragments that it is difficult 

 to observe the origin of the steam. We 



