Geology. — “On the hot “Lahar’ (mud flow) of the Valley of Ten 
Thousand Smokes. (Alaskay’. By B. G. Escuer. (Communicated 
by Prof. G. A. F. MOLENGRAAFF). 
(Communicated at the meeting of November 26, 1921). 
After numerous expeditions to the Mt. Katmai volcano and the 
“Valley of ten thousand smokes” in Alaska, Roperr F. Griees has 
amply communicated his observations (lit. 1—6). 
Particularly he has viewed the great hot mud flow which occu- 
pies an area of 137 sq. Km. in the valley of ten thousand smokes. 
As he points out (lit. 5, p. 142) *) he specially treated this pheno- 
menon so extensively because he felt obliged to give an explanation 
which would be a novelty in volcanology. 
We should be very grateful for his frankness and for the oppor- 
tunity he has afforded his colleagues to venture on an other explanation 
of the great hot mud flow. 
It is evident that Grices is unaware of the nature of the volcanic 
explosions of the A/ut voleano in Java and it seems to me that this 
voleano gives us the key for the disentanglement of the enigma 
which was posed before Grices. 
We may summarize the observations and explanations of Griggs 
as follows ’). 
A couple of valleys with an aggregate length of 32 Km. are 
covered by a hot mud flow, which left practically, everywhere 
a “high water-(mud-)mark” on the surrounding slopes of the moun- 
tains. Stratified ash from the explosion of Mt. Katmai in June 1912 
1) In the discussion of this remarkable terrane we have set down numerous 
considerations which would be quite superfluous if it were located in a 
district more accessible to geologists, so absolutely clear are its major relati- 
ons. But, recognizing that under present circumstances it would not be practi- 
cable for all geologists who might be skeptical to go and see it for themselves, 
we have tried to supply the answers to all the questions likely to arise in 
the minds of such skeptics” (lit. 5 p. 142). 
and: 
,. would further add that I am not committed to any theory of the origin 
of this curious terrane, but will be glad to accept any other interpretation 
that can be suggested, provided only that it is consistent with the facts as 
found in the field. Certainly any suggestion that would relieve us of the 
necessity of postulating an entirely new type of volcanic action will be most 
welcome” (lit. 5, p. 119). 
*) For the present I do not take into consideration the most recent version 
of Griags (lit. 6). 
