p. Waitz— Popocatepetl Again in Activity. 81 



^j^T. yi. — Popocatepetl again in Activity; by Paul 



Waitz. 



For some months we have seen from Mexico City on 

 clear days of the rainy season that small eruption clouds 

 were rising in puffs from Popocatepetl. This was a 

 rather unusual spectacle, as since 1720, the year in which 

 the last historically confirmed eruption occurred,^ the 

 volcano apparently has shown only a very slight activity 

 of fumaroles and solfataras. The long duration of this 

 year's rainy season was not favorable for an investigation 

 of the state of the mountain. As soon as better weather 

 promised to allow of a successful ascension I gladly 

 accepted the invitation of the Sociedad Cientifica '^ Anto- 

 nio Alzate ' ' to study the volcano. After careful prepara- 

 tion for the excursion I began the ascent in the company 

 of some friends on the 10th of October of the present 

 year ; favored by wonderful weather conditions and good 

 luck, the excursion had the very best of success. 



We started from Amecameca (2532 m. above sea-level) 

 on horseback at noon and after a frve hours' ride through 

 beautiful forests at sundown, reached Tlamacas, a locality 

 situated on the north slope of the volcanic cone at a height 

 of about 4000 m. above sea-level. The ranch house which 

 years ago stood there at the side of a small hut used for 

 sulphur smelting, had long since been destroyed by the 

 revolution, but we found a few huts made of logs and 

 covered with zacate-grass, which offered us a good shelter. 



After a rather uncomfortable night on account of the 

 low temperature, we started on the 11th of October at 

 4 A. M. on horseback from Tlamacas and rode as far as 

 Las Cruces (about 4500 m.) from w^hich point the horses 

 were sent back to Tlamacas. From here on we made use 

 of a fairly good zigzag trail which had been constructed 

 last winter by the sulphur diggers {azufreros) : a proof 

 that in the past winter no snow lay on the slope of the 

 mountain, although in former years a cover of snow used 

 to reach down to Las Cruces. While this cover of snow 

 has disappeared almost entirely, the glacier of the 

 volcano, which formerly on account of the thick cover of 

 snow could not be observed at all, is still well preserved. 

 This glacier lies in a depression between the main cone 

 and a prominent promontory, the Pico del Fraile, and 

 has been preserved up to the present date because the 



Am. Jour. Sci.— Fifth Series, Vol. I, No. 1.— January, 1931. 

 6 



