54 NOTES ON THE 



color, and not rarely perfectly black, sometimes with a glazed surface not unlike 

 obsidian. 



"Within six or seven miles from the crater, the layers of volcanic sand and 

 pumice become very regular, as seen at all places where they are exposed on the 

 sides of the ravines and gullies. The stratum immediately beneath the surface is a 

 layer of coarse, black sand, three feet thick, then succeeds a layer of reddish-yellow 

 pumice, only one quarter of this thickness, then again a layer of sand, and so on 

 alternately; showing that at the last eruptions a shower of pumice first issued, 

 which covered the ground from three inches to a foot in thickness, to a distance 

 of six or seven miles from the crater; this was followed by a shower of gray or 

 black sand, the deposit from which reached a thickness of from three to six feet. 

 An interesting proof that the last eruption was at no very remote date is afforded 

 by the trunk of a pine-tree, which Avas found, when I last ascended the volcano, 

 in company Avith Prof Monross, in June, 1857, imbedded in the last layer of 

 pumice, below the uppermost strata of volcanic sand, more than three feet below 

 the surface. The outside or sapwood of the tree had decayed, but the interior 

 wood being impregnated with turpentine was still perfectly fresh and well pre- 

 served. Certainly not many centuries can have passed since this tree was buried. 



■ About three miles from the point where the trunk of the pine-tree was found, 

 we reached the highest human residence in this part of the world. It consists 

 of a few Indian huts and a log house, in front of which are the ovens for purify- 

 ing the sulphur which is brought down from the crater. The place is called 

 "Rancho Tlamacas," and has an elevation of nearly 12,800 English feet above the 

 level of the sea. Here the traveller can remain for the night, and, leaving early 

 the next morning, may reach the edge of the crater about noon without much 

 exertion. 



About half a mile to the west of this "rancho" we crossed a ridge of rock, 

 which runs from the "Pico del fraile," situated on the west side of the highest 

 peak, to the Ixtaccihuatl, rising at several points into irregular peaks. This ridge 

 is not a stream of lava from the present crater, but a dike of ancient volcanic 

 rock (gray stone), upheaved by the later action of the volcano. About 400 feet 

 above the rancho, or at nearly 13,200 feet of absolute height, the last stunted 

 pine-trees are seen, and this may be assumed as the limit of vegetation ; some Aviry 

 grass, only, groAving in bunches, is found for a short distance higher up. During 

 the summer months, or, more properly, the rainy season, the suoav often extends 

 on the north and Avest side of the volcano doAvn to this limit, or even loAver, as Ave 

 experienced during the latter part of June, haA'ing been for three days enveloped 

 in a dense fall of snoAv, at the Rancho Tlamacas, AA'hicli covered the ground nearly 

 twelve inches deep, although much of it melted immediately. This snoAv-storm 

 extended at least a thousand feet further doAvn, terminating at a heiglit of from 

 11,700 to 11,800 feet. 



The limit of perpetual snoAv is about 1000 feet higher than the limit of vegeta- 

 tion, or, on the north and northAvest side of the mountain, 14,200 feet. On tlic 

 south and southeast side it is mucli higher, and from bcloAV there can be traced 

 black lines, Avhich are in reality la\a-strcams, up to the edge of the crater (17,200 



