THE NATIONAL GEOGRAPHIC MAGAZINE 



139 



incrust the mud in their vicinity with 

 copious deposits, giving the adjacent 

 ground a most fantastic appearance. 

 These incrustations take on all colors im- 

 aginable and in many places give rise to 

 very beautiful formations. The prevail- 

 ing hues are perhaps those due to the 

 gray and green and yellow alums, which 

 build out curious crystalline structures 

 simulating lichens growing on the ground. 



DEPOSITS ALL COLORS OP THE RAINBOW 



Over large areas the ground has been 

 burned to a bright red by the heat. The 

 variations in the intensity of the color 

 produced are extremely beautiful, includ- 

 ing, as they do, all shades from orange 

 and brick red to bright cherry reds, pur- 

 ples, and on down to black, with occa- 

 sional contrasting streaks of blue. This 

 type of coloration is most pronounced in 

 areas originally occupied by small fuma- 

 roles which have burned out. In places 

 the ground has the appearance of having 

 been burned with fire for a mile at a 

 stretch. 



Around the larger vents the ground is 

 more commonly colored a dull pink by a 

 deposit which cements the loose, sandy 

 particles of ash into compact masses like 

 concrete. In some of the largest vents 

 such pink and red incrustations are the 

 only ones developed, but more often spots 

 of brilliant yellow and orange also occur 

 in beautiful contrast with the pink ground 

 color. 



FLOWERS OF PURE SULPHUR 



These yellows are mostly due, of 

 course, to sulphur, which is very common. 

 There are some places where one can 

 gather crystals of sulphur, almost free 

 from impurities, by the bushel. And up 

 on the mountain side above the crater of 

 Novarupta is a great yellow spot of sul- 

 phur conspicuous for miles. Sulphur oc- 

 curs most often in small crystals com- 

 pacted into solid cakes, but occasionally 

 we found it lining the throat of a fuma- 

 role in long, branching, needle-like crys- 

 tals (flowers of sulphur), very beautiful 

 under a lens. 



With the yellow sulphur are often de- 

 posited masses of a bright orange crys- 

 talline substance whose composition we 

 did not know. These are generally de- 



posited in the cracks of the characteristic 

 blue mud that abounds around many of 

 the groups of fumaroles, especially in 

 places where there is considerable dif- 

 fused activity, reaching the surface 

 through innumerable small jets rather 

 than by a single large vent. 



Needless to say, the color combination 

 presented by the orange and blue is as 

 beautiful as it is unusual. In similar 

 fumarole groups where the activity is not 

 quite so intense the surface of the same 

 blue mud is covered with a rich chestnut- 

 brown crust, whose varied tones would 

 of themselves excite the highest admira- 

 tion were they not eclipsed by the other 

 more brilliant colors. 



In still other places the prevailing de- 

 posits are of a white, chalky character, 

 recalling the geyserite of the Yellowstone 

 Park. These white vents excel all the 

 others in the delicacy of their coloring, 

 for they are lightly tinged with yellow 

 and pink, giving them a creamy, flesh- 

 colored appearance, even more beautiful 

 than the brilliant masses of color else- 

 where developed. 



In addition to all these colors, algae 

 have formed a deep-green incrustation 

 over the ground close up to some of the 

 vents, in places where at first sight one 

 would suppose the ground was too hot to 

 permit the activities of organisms of any 

 kind; but the insulating properties of the 

 soil are so good that great variations in 

 temperature may occur within a few 

 inches. 



We much desired to make accurate 

 color studies of the characteristic de- 

 posits, but the time at our disposal was 

 altogether too short to permit of such de- 

 tailed exploration. Indeed, it should be 

 emphasized that there is material in this 

 wonderful valley to repay months of 

 careful study, and that all we could do 

 was to examine hastily the major fea- 

 tures, leaving thousands of important 

 seats of activity without even so much as 

 a cursory visit. 



But there are a few special features 

 which cannot be passed by without more 

 detailed description. 



FISSURE LAKE 



Across the head of the valley stands the 

 three-peaked bulk of Alt. Mageik, smok- 



