108 EARTH FEATURES AND THEIR MEANING 



form of frozen lava has sunk more or less rapidly to levels far 

 below the black ledge and from 900 to 1700 feet below the crater 

 rim. Following this descent a slow progressive rise is inaugurated, 

 which has sometimes gone on at a rate of more than a hundred 

 feet per year, though it is usually much slower than this. When 



FIG. 103. View of the open lava lake of Halemaumau within the crater of 

 Kilauea, the molten lava shown cascading over the raised lava walls on to the 

 floor of the pit (after Pavlow) . 



the platform has reached a height varying from 700 to 350 feet 

 below the crater rim, another sudden settlement occurs which 

 again carries the pit floor downward a distance of from 300 to 700 

 feet. 



The draining of the lava caldrons. The changes which go on 

 within the crater of Mokuaweoweo, though less studied than 

 those of Kilauea, appear to be in some respects different. Here 

 every eruption seems to be preceded by a more or less rapid influx 

 of melted lava to the pit of the crater, this phenomenon being 

 observed from a distance as a brilliant light above the crater 

 the reflection of the glow from overhanging vapor clouds. The 

 uprising of the lava has often been accompanied by the formation 

 of high lava fountains upon the surface, and the molten lava 

 sometimes appears in fissures near the crater rim at levels well 

 above the lava surface within the pit. 



