48 CRATER LAKE, OREGON 



sible that other small volcanic cones might be found. This sug- 

 gestion is borne out by the soundings of the lake, which appear 

 to reveal two other cases, but they do not rise to within 400 feet 

 of the surface of the water. It is evident that the volcanic 

 eruptions upon the bottom of the pit have partially filled it up. 

 Originally it may have been much more than 4,000 feet deep. 



Given the pit with water-tight walls, there is no difficulty in 

 forming Crater lake, for in that region precipitation is greater 

 than evaporation. The lake does not fill up and. overflow. The 

 surplus water must have a subterranean outlet, probably toward 

 the southeast, where the region is traversed by extensive breaks 

 in the rocks, and abounds in excellent springs. 



The color of the lake is deep blue excepting along the borders, 

 where it merges into various shades and tints of green. It is so 

 transparent that even on a hazy day a white dinner plate 10 

 inches in diameter may be seen at a depth of nearly 100 feet. 

 It contains no fish, but a small crustacean flourishes in its waters, 

 and salamanders occur in abundance locally along the shore. 



The level of the lake oscillates with the seasons. During the 

 rain}'' winter it rises, and in the summer it falls. In August last 

 observations were made for twenty-two days, and the lake sank 

 at the rate of one inch for every five or six days, depending 

 somewhat on the conditions of the weather. The Mazamas have 

 established a water gauge, and it is hoped that an extended series 

 of observations may be obtained in the future. 



Mr B. W. Evermann, of the U. S. Fish Commission, who vis- 

 ited the lake last summer, made some interesting observations of 

 its temperature. At 1 p. m., August 22 — 



The temperature of the surface water was 60° 



At a depth of 555 feet the temperature was 39° 



At a depth of 1,043 feet the temperature was 41° 



At a depth of 1,623 feet (on the bottom) the temperature was 46° 



The increase of temperature with the depth suggests that the 

 bottom may yet be warm from volcanic heat, but more observa- 

 tions are needed to fully establish such an abnormal relation of 

 temperatures in a body of water. 



Aside from its attractive scenic features, Crater lake affords 

 one of the most interesting and instructive fields for the study 

 of volcanic geolog}^ to be found anywhere in the world. Consid- 

 ered in all its aspects, it ranks with the Grand Canyon of the 

 Colorado, the Yoseraite valley, and the Falls of Niagara, and 

 should be set aside as a National Park for the pleasure and in- 

 struction of the people. 



