THE KATMAI REGION, ALASKA 



579 



adjacent to it but beyond its borders, fallen trees lie as if over- 

 thrown by a violent wind accompanying it. This is observable 

 along the margin of the deposit and also on those slopes of the 

 Katolinat Range that lie at the foot of the valley and face up the 

 valley in the direction from which the flow advanced. 



Katmai crater could hardly have been its source, as physical 

 obstacles stand in the way of distribution from that point, and 



#^ 



Z'i^. 



Fig. 8. — The great sand-flow of the Valley of Ten Thousand Smokes, overlain 

 by stratified ash from the Katmai ash- fall; view taken at junction of Knife Creek 

 (at left) and River Lethe (at right, nearly concealed by steam cloud). The stratified 

 terraces just above stream-level are not part of the sand-flow but are the result of 

 recent stream deposition. Photograph by E. G. Zies, 1919. 



glaciers that still cover the slopes of Katmai on this side would 

 probably show noticeable effects from the movement of such an 

 incandescent avalanche over their surfaces. The distribution of 

 the material is such that there seems to be almost no escape from 

 the conclusion that it originated within the valley itself and that 

 we must look for its source in vents situated on the floor of the 

 valley or on the lower slopes of the mountains at its head. Such 



