49 



The configuration and practically continuous course of the high 

 sand mark entirely around the Valley basin seem to leave no escape 



The edée of the incandescent sand flow of the 

 Valley of Ten Thousand Smokes. 



Photo by P. H. Hagelbarger. 



The picture was taken about the same distance, circa 5 km, 

 above the terminus, as the one of Klut. Contrast the total de- 

 struction here with the uninjured trees at Blitar. On the original 

 surface where revealed by erosion may be seen the stumps of 

 trees burned off just above the ground. 



from the conclusion that the material originated within the confines 

 of the Valley itself, that the vents from which it issued were located 

 within the limits of the high sand mark. Since vents in this situation 

 would be choked by their own products unless vigorously explosive *) 

 we need not be surprised if the points of issue are not certainly 

 identifiable. 



The distribution of the flow, sloping as it does both ways across 

 two divides, shows that it could not have come from any single 

 vent. A number of considerations suggest that many vents, rather 

 than a few, were probably concerned. The character and distribution 

 of the present fumaroles in the Valley, together with some other 

 circumstances, likewise make it appear more probable that the ori- 

 fices were fundamentally fissures, not centralized vents on the model 

 of the ordinary volcano. 



The nature of the vents from which the incandescent material 



1) Since the type of material composing the tuff is strictly confined to the 

 Valley basin, not a particle of it being found on the adjacent mountain slopes, it 

 is clear that the magma must have issued comparatively quietly, albeit the material 

 is now thoroughly fragmented, indicating a degree of inflation comparable with 

 the magma of Katmai which exploded with great violence. 



