CRATER LAKE, OREGON. 375 



as real springs, whose water must find its way in from the snow upon 

 the outer slope. 



The boldest portion of the rim, excepting perhaps Llao Eock, is 

 Button Cliff, which is made more impressive by the deep U-shape 

 notches on either sde and the Phantom Ship at its foot (fig. 12). The 

 notches mark poinl:'i where the canyons of Sun and Sand creeks pass 

 through the rim to the cim overlooking the lake. In figure 13, which 

 shows the same view as figure 12, but in the opposite direction, the 

 notch at the head of Sun Creek Canyon is well illustrated. These 

 canyons, due to erosion on lines of drainage, belong to the period when 

 the topographic conditions in that i-egion were quite unlike those of to- 

 day. They were carved out by streams of ice and water descending 

 from a point over the lake, and their presence, ending as they do in 

 the air hundreds of feet above the present water level, affords strong 

 evidence in favor of the former reality of Mount Mazama. 



The Phanton Ship (fig. 14) is a craggy little islet near the border 

 of the lake under Button Cliff. Its rugged hull, with rocks towering- 

 like the masts of a ship, suggests the name, and, phantom-like, it dis- 

 appears when viewed in certain lights from the western rim. Stand- 

 ing in line with an arete that descends from an angle of the cliff, it 

 possibly marks a continuation of the sharp spur beneath the water, 

 or perhaps, but much less likely, it is a block slid down from the 

 cliff. Whatever its history, it attracts everyone by its beauty and 

 winsomeness. 



At times of volcanic eruption the lava rises within the volcano until 

 it either overflows the crater at the top or, by the great pressure of the 

 column, bursts open the sides ot the volcano and escapes through the 

 fissure to the surface. In the latter case, as the molten material cools, 

 the fissure becomes filled with solid lava and forms a dike. The best 

 example of this sort about Crater Lake appears along the inner slope 

 directly north of Wizard Island, and is locally known as the Bevil's 

 Backbone. It is shown in figures 3 and 11 across the left end of 

 Wizard Island. This dike rock, standing on edge, varies from 5 to 25 

 feet in thickness and cuts the rim from water to crest. Bikes are most 

 numerous in the older portion of the rim under Llao Eock. They do 

 not cut up through Llao Rock and are clearly older than the lava of 

 which that rock is formed. Bikes occur at intervals all around the 

 lake and radiate from it, suggesting that the central volcanic vent 

 from which they issued must have been Mount Mazama. 



There is another important feature concerning the kinds of volcanic 

 rocks and their order of eruption and distribution about the rim of 

 Crater Lake that is of much interest to the geologist. All the older 

 lavas comprising the inner slope of the rim, especially toward the 

 water's edge, are andesites. The newer ones, forming the top of the 

 rim in Llao Eock, Eound Top, and the Eugged Crest about the head 

 of Cleetwood Cove as well as at Cloud Cap, are rhyolites. Other later 



