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POPULAR SCIENCE MONTHLY 



This 'cave' was probably the place where Baron Miiller, who climbed 

 the mountain in 185G, stopped, and where nearly all the mountaineers 

 who have attempted the, ascent since have passed the night. Miiller 

 speaks of the 'granite' walls of the cave and other tourists use the same 

 term. But there is no granite here nor elsewhere in the region. The 

 rock masses forming the mountain are singularly uniform. They are 

 eruptive rocks of prevailing dark grayish or brownish color composed 

 of crystals of augite and plagioclase in a fine ground mass and are called 

 andesite. In places glassy masses of obsidian appear, and in others vol- 

 canic tuffs and ashes, but in no place is there granite or gneiss. 



Fig. 4. Forest on Mount Orizaba in the Distance— 100 Miles away- 



iztaccihautl. 



-Popocatepetl and 



The following morning at six o'clock, after a hurried breakfast, one 

 guide and I started for the summit. In a few minutes we were above 

 the timber line. Two hours of walking brought us to the snow line, 

 that day at about fifteen thousand feet. 



At the lower levels the snow is finely crystalline, very compact and 

 of the variety known as 'firn' or 'neve.' It affords excellent footing 

 to the properly shod climber. Toward the top of the mountain it is 

 softer, though the individual flakes are never large, and the feet sink 

 in to the shoe tops. The beauty of the snow furnishes one of the great 

 rewards to the tourist. The spike of an alpine stock leaves after each 

 thrust a hole of wondrous green in the glittering white mass. The 

 snow fills the chasms of the mountain, smoothes out its ridges, softens 



