43 



Up till the last eruption the ejecta had consisted entirely of basic- 

 andesite which had ponred out without any explosive accompani- 

 ments of a major sort. Between the last of these flows and the 



Katmai volcano before the eruption 



^ y I 



5 KILOMETERS 



OA5/ ^ I I 



/TO 7260 \ 



I I O 7360 t , 



' I B ; ' ; ' 

 ) r'y / 



' ' ' , 



I I 





ƒ ,' ,' \ \ \ \ ' ,■ ' I 



■' }'•. \ * \ \ \ , ' , 



' / I O750O I \ 1 / 1' r / / 



/ / *—' KATMAI VOL.; ; / / 



-ssoo-"' . 



- — ^oo'^' 



-— 3000' 



This map shows that there could have been no crater lake 

 before the eruption. The site of the present crater (cf. map on 

 page 45) was occupied by three peaks whose position and 

 altitude were determined with precision by the United States 

 Coast and Geodetic Survey, from whose Chart N". 8555 the 

 figure is traced. 



recent outburst had intervened a pause probablj' matiy centuries in 

 duration and when activity was resumed it differed materially from 

 what had preceded. The Eruption of J 912 consisted entirely of 

 fragmental products rather than molten lava. First came the great 

 outpour of ash and pumice which is the subject of this note. Then 

 Mt. Katmai blew up in a series of extremely violent explosions 

 which left behind the present gigantic crater in place of the former 

 mountain summit. The total quantity of rock that disappeared from 



