290 
On the lahar of the Klut pseudo volcanic phenomena were 
observed in connection with evaporating rain- and groundwater and 
the sudden appearance of steam under great pressure. That this 
pressure can be rather high may be concluded from the temperature 
of 360°C. which KemMeRLING measured at a gas emanation from the 
lahar some days after the eruption. 
The highest recorded temperature in the Valley of Ten Thousand 
Smokes was 645° C. (lit.6 p. 250). I should not dare to assert that 
the smokes in the latter valley are coming all from the heat which 
is locked up in the lahar. 
It is true that the material of the lahar is an excellent insulator 
against loss of heat, so that it seems quite possible that the lahar 
of Mt. Katmai may still retain a part of his own heat after years, 
but Grices mentions three facts showing that there must be still 
another source of heat in the valley. 
In the first place true solfatares were observed with the subli- 
mation products sulphur and the two sulphides of arsenic (lit. 4 p. 
105) which fact in accord with our experience must be brought 
back to magma the below. 
Secondly, Gricges succeeded in finding fumaroles not situated on 
the mud flow but beside it in the Jurassic sandstone, which locally 
forms the underlying terrane of the valley (lit. 4 p. 111). 
Thirdly at one end of the valley lava appeared and formed the 
lava-plug in Novarupta voleano (lit. 4 p. 111). 
These three facts do not agree with the properties of the hot 
lahars from the Klut volcano and are explained by Griaas on the 
supposition that under the valley the magma lies near the surface. 
On the other hand it is certain that the Katmai lahar must form 
pseudo-voleanic phenomena just as the Klut lahar did; so it will 
probably be possible to conclude from detailed data whether we must 
indeed suppose (lit.4 p. 116) that the area in the vicinity of which 
the magma reaches nearly to the surface has a length of 32 Km. 
or that parts of this terrane do not exhibit signs of real voleanic 
phenomena, but only of pseudo-volcanic lahar phenomena. 
Probably this might be settled by help of analyses of the fumarole 
gases and a map of the distribution of the different kinds of gas. 
It seems conceivable for instance that the part of the Katmai 
lahar whieh flowed over Katmai-pass towards the southeast does not 
have real solfatares. In his last paper (lit.6 p. 248) Grices points to 
the fact that the intensity of some fumaroles was in 1919 lower than 
in the preceding years. Some fumaroles had in 1919 a markedly 
lower temperature, others (about a hundred) did not exist any longer. 
