F. A. Perret — Lava Fountains of Kilauea. 139 



Art. XIV. — The Lava Fountains of Kilauea ; by Frank 



A. Perret. 



The observer, standing upon the brink of Halemaumau, 

 looks down into a pit-crater with the vertical, stratified walls 

 characteristic of the type and with, possibly, a "black ledge" 

 forming a shelf at some distance below the edge and marking 

 a former level of the lava column. If this is still receding, a 

 tains of broken fragments of the ledge — fallen for want of 

 support from below — softens the lower angle, but if, on the 

 contrary, the lava has been rising for some time, the crater 

 floor will extend as an apparently almost flat surface directly 

 to the vertical walls of the pit. In what may be considered 

 the normal state of activity this crater floor consists of a 

 central liquid portion — the lava lake — and a surrounding 

 "shore" of solidified lava chilled by conduction to the crater 

 walls, and growing vertically with the rising lake by overflows 

 from its surface. The liquid portion is maintained at a higher 

 level than the surrounding solid surface by a retaining rim 

 which is formed by accretion during the various oscillatory 

 movements of the constantly agitated liquid and by the spat- 

 tering of peripheral fountains. 



The condition of the crater floor, as it appeared in July, 

 1911, is shown in fig. 1, and upon the lake may be seen one of 

 the " Floating Islands" to the discussion of which a subsequent 

 paper is to be devoted. 



The form of the true crater — as seen when drained of its 

 contents by a subterranean, lateral outflow of lava — is that of 

 a basin over three hundred meters in depth terminating below 

 in a large, well-like opening more than a hundred and twenty 

 meters in diameter, as shown in a sectional design by the 

 survey of E. D. Baldwin in August, 1902. 



In times of abnormal activity there is re-fusion of solidified 

 material and a wholly liquid floor (lake) extending to the sides 

 of the pit with a surface practically covered with fountains. 

 Occasionally the lava column fills the basin and overflows into 

 the main crater of Kilauea, thus adding to the flat cone which 

 is gradually filling that greater pit. 



Let us now observe the lava lake under normal conditions, as 

 shown in fig. 1. The surface material is moving majestically 

 from some point, often under an overhanging bank where it is 

 rising from below, to one or more localities — it may be at the 

 opposite end of the lake — where it is evidently descending. 

 Under the bank it is seen to be brightly incandescent, but, upon 

 exposure, there forms upon its surface a film of a satiny and 



