292 
It might be possible that these observations have relation to pseudo- 
fumaroles. 
In the discussion of the great mud flow I have till now used 
only the papers of Griaes litt. 1—5. Especially in lit. 5 he gives 
many detailed observations on the mudflow. It may be noted that 
he speaks of a “high-water-mark” (lit. 5 p. 121) and in the legend 
accompanying a photograph (lit. 5 p. 126) of a “high-mud-mark”’. 
In lit.6 however a “high-sand-mark” (p. 232) is for the first time 
mentioned and it is evident that Grices interprets the tuff-filling of 
the valley by the eruption of dry ash and sand through hundreds 
of little volcanoes in the bottom of the valley. He speaks of “the 
tremendous outflow of incandescent sand” (p. 241) and in the legend 
to a photograph (p. 228) we find the expression ‘“‘hot-sand-flow”’. 
The mechanism of this hot sand-flow is for the present insufficiently 
explained: ,,The continuity of this ,,high-sand-mark” shows clearly 
that the incandescent mass was not poured down one of the adjacent 
mountain sides into the valley, but must have originated from vents 
within its confines. This is clearly evidenced by many additional 
facts which cannot be detailed here. During the whole period of 
flow the mass was probably kept in a state of constant turmoil by 
the continued evolution of gas from the substance of its solid com- 
ponents” (lit. 6 p. 232). 
In connection with the photograph of Novarupta (lit. 6 p. 230) 
we find mentioned: ‘It is probable that a considerable fraction of 
the incandescent sand came from this vent.” 
This new hypothesis of Grices is manifestly invented because on 
a closer view he no longer found it probable that a hot mud flow 
welled out of the bottom of the valley. 
However this may be, his detailed observations communicated in 
lit. 5, have convinced me that the tuff-filling of the „Valley of ten 
thousand smokes” is brought about by a hot lahar coming from the 
crater lake of Mt. Katmai. 
We can therefore predict with a great approach to certainty that 
at the next eruption of Katmai-voleano hot lahars will again occur 
and principally on that side or those sides where the crater-rim is 
now lowest. 
Nov. 21, 1921. 
