GEOLOGY AND TOl'OGRAPllV OF HAWAII. 167 



1iiiik1i'(hI feet hclow the liiizhcst [)(>iiit "' <iii the rim >>f llic ci'jitci'. aii'l lluil in 

 historic time the hlnck lava Hoor has iicvci- hccii liinlici- than it is ;!t llic present 

 time — there should be little tliftieiilly in f(»l lowing' a eondeiised lii^ory of Kilaiu^a. 

 For oui' ])iii'|)(ise its history can l)est he related by se'ectin^' e.xti'aets from a 

 few of the best descriptions of conditions at the eratei- iaken ri-oiii 1 he many 

 accounts w litten l)y eye Avitnesses. 



An Exploded Mountain. 



This is done with a view to bringing' out two points: the first that just as 

 Manna Loa is an excellent example of its type. Kilanea is an example of a dif- 

 ferent and rarer type, namely, a broken down or exploded voieaiio, that con- 

 tinues active. It is for this reason that it is spoken of as "safe" and. so far as 

 volcanoes can be, is regarded as perfectly tame, "docile," and well-behaved. 

 The second point to be developed is that of the character and periodicity of its 

 normal eruptions. 



The explosion or explosions which undoubtedly l)roke Kilanea down and 

 prevented it from l)uilding up as Mauna Loa has liuilt up, has left an un- 

 mistakable geologic record. 



Evidence of what transpired is to be found on every hand. These ex- 

 plosions, of Avhich there apparently were several, must have l)een in the very 

 distant past. Their etfect was to weaken and shatter the walls that surrounded 

 the crater, leaving the. mountain scarred by a series of radial and concentric 

 cracks that could have been produced only by an explosion deep down within 

 the crater. As a consequence, v.'hen the molten lava rises to a certain level in 

 the crater, the pressure becomes so great on the lateral walls of the volcanic pipe 

 that the lava Hood breaks through some weak spot, usually far down under- 

 neath, and the liquid lava often tlows (juietly out to sea through .some old 

 deep-hidden conduit. 



The Rise and Fall of the Liquid Lava. 



Never since the coming of white man to Hawaii has there I)eeu suffi- 

 cient force to lift the liquid lava over the l)i'ink of the crater. As a result of 

 these subterranean ventings Kilanea is esteemed as the best example of a 

 "welling" crater to be found. 



The history of this volcano has been that through a period of niontlis or 

 years'' the pit of Ilalemaumau '^ tills up little by little until it reaches the 

 maximum of height and pressure that the walls will beai-. Then. owiuL;- to the 

 enormous lateral pressure exerted by the molten colunui ol la\a. tiie weakened 

 walls giv(^ way and the crater vents itself. The la\a lake recedes to a lower 

 level, often disappearing entirely, oidy to lill up again in due process of lime. 

 Thus in the welling and venting of Kilanea we have a sort of barometer that 

 indicates the conditions prevailing far down beneath the island. 



■'' Uwekahuna. " Perhaps owing to soine uiiUnown iiilluriicc of the goddi'ss Pelo — wlio knows! 



' The house of everlasting fire. 



