78 FIELD COLUMBIAN MUSEUM—GEOLOGY, VOL. I. 
All along the route frequent views of Ixtaccihuatl and Popocate- 
petl may be gained, though their summits are much of the time 
hidden by clouds. These clouds are, during the dry season, of the 
cumulus type, and frequently invest the summits of the mountains 
when the rest of the sky is clear, indicating that the chilling of the 
moisture of the air by the cold of the summits has formed them. 
This is further indicated by the way in which they can be seen to 
gather and roll down the mountain slopes. They usually lie at about 
the height of the snow line on the mountains, 13,000 feet above the 
sea, but under other conditions of the atmosphere frequently descend 
lower. 
Ameca is on the western side of the Sierra, standing upon a 
level plain, once, probably, as has been said, the bed of a lake, now 
at a height of 8,132 feet above the ievel of the sea. Near the western 
edge of the plain rises a dome-like hill about 400 feet in height 
clothed with beautiful pines and cedars. This is called the Sacro- 
monte or sacred hill. Upon it stand two ancient churches, one of 
which contains an image of Christ of especial interest to the devout 
Catholics of Mexico. For this reason thousands of pilgrims come to 
Ameca during each year, from all over Mexico, to worship at its 
shrines. Moreover, the natural beauty of the spot, and its cool, 
delightful climate make it an attractive resort for picnic parties, who 
do not fail to improve the opportunities the town affords for rest 
and refreshing. There is an excellent hotel in the town where good 
food and lodging can be obtained, as well as provisions for a trip to 
the mountains. 
Horses and guides can also be procured in the town, from Sr. 
Don Pedro de la Noriega, a young and enterprising Mexican, pro- 
prietor of one of the largest ¢#endas or stores, and agent for the 
owner of the sulphur mines. By informing him in advance, guides 
and horses can be had in readiness to meet parties on the arrival 
of the morning train, and thus the ascent to the snow line can be 
accomplished the first day. For the ascent of Popocatepetl permis- 
sion should be obtained from General Sanchez del Ochoa, the owner 
of the sulphur mines, now residing in the City of Mexico, in order to 
camp at the so-called Ranch of Tlamacas. A letter of introduction 
from him to Sr. Don Pedro de la Noriega will also be of assistance in 
securing prompt and obliging service. If one does not speak the 
Spanish language, a companion should by all means be obtained who 
can act as interpreter, for none of the residents of Ameca speak 
English, and the resources of sign language are quite inadequate for 
so arduous an undertaking as the ascent of one of these mountains. 
