ORIGIN OF CRATER LAKE, OREGON 



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Park, 191 2, entirely uncovered by any material that could have been 

 blown out from Mount Mazama to make the great depression for 

 Crater Lake if Mount Mazama was blown away a la Katmai and 

 not engulfed. 



The most striking evidence of the engulfment of Mount Mazama 

 is afforded by the inflowing stream of dacite, Fig. i, from the 

 notch produced by the cave-in at Rugged Crest down the inner 



Fig. I. — The inflow of dacite at Cleetwood Cove of Crater Lake 



slope of the rim to Cleetwood Cove of Crater Lake. The view 

 shows the whole length of the inflow from the notch of Rugged 

 Crest to the shore of the lake, and it appears that Mount Mazama 

 sank away about the time the final flow of dacite occurred, for the 

 dacite beneath the crust at Rugged Crest was still soft enough to 

 flow and to cause the crust to break and cave in. The broad flow of 

 dacite from Rugged Crest northeast down the outer slope of Mount 

 Mazama is shown in Figure 1, also the short flow inward to the lake. 



