82 



Kilaiiea and Manna Loa. 



On the northern edge of this plain are extensive snlphiir beds, that is to say, 

 thev cover a large space although containing but little sulphur, under a perpendicular 

 ledge of clinkstone nearlv a hundred feet high. Thej- are simply great piles of decom- 

 posed lava through which steam and sulphurous vapors constantly escape through a 

 thousand apertures, depositing beneath the cool crust the most beautiful, almost 

 acicular crystals of sulphur.''^ The soil formed by the decomposition of the rock by 

 sulphurous vapors is quite unlike that resulting from the action of steam alone; it is 







n 



m^^^'^^"^ 





^>.-.i^^. 





'<^.^' 



r^^gL.liat;. ■.^fTi^ yl'*' .^>fl.^gg-.^-^ -J. ■- 





FIG. 55. Fl-.MAROLE IN SIDE W \hh WITH .SULPHUR CRYSTALS, 1S89. 



light gray or yellow, and does not form a plastic mud as readily as the latter, which 

 is red and smooth to the tcnich. In some places the sulphates of oxides of copper, 

 iron, sulphates of soda, lime and alumina were forming within minute fissures, and 

 the silica thus set free was gradually consolidating the earth into a iirm crust when- 

 ever the supply of steam ceased, and we could often raise large slabs of this curious 

 conglomerate. Metamorphism was progressing rapidly under the combined iniluence 

 of heat and moisture. Twigs and leaves were fast passing into the condition of fossils 

 in this hardening earth. All the sulphur found here is deposited from the vapor, 

 seems to be tolerably pure and is of a light yellow color indicating the absence of 



'Wlthouffh the two illustrations of the sulphur bank were taken by the author twenty-five years after this visit, 

 there is little change in the first and none in the second so far as the deposit of crystals is concerned. In 1.S64 the 

 sulphur proved too strong for the wet plate process then used. 



[460] 



