PopPpocATEPETL AND IxXTACCIHUATL—FARRINGTON. III 
PORFIRIO DIAZ GLACIER. 

The first published mention of this glacier, of which I am aware, 
is made by Felix and Lenk in their work already cited, the latter trav- 
eler having crossed it in his attempt to ascend the mountain. Its 
various features convinced him thatit was an actual glacier, though he 
could find none of the characteristic scoured and scratched surfaces, 
which usually accompany a moving body of ice. His observations, 
which are but meager, are given in the work cited. 
Heilprin and Baker visited the glacier in 1890 in their attempt to 
ascend the mountain, and Heilprin, in his report,* proposes thename 
of Porfirio Diaz Glacier for one of several glacial streams (s¢c) which 
descend the slopes to a depth of 14,500 feet. He gives no further 
description of the glacier. Baker, however,} states that glacial tables 
and moraines were noted by the party. I know of no other pub- 
lished description of the glacier, nor does the fact of its existence 
seem to be generally appreciated. Many well-informed residents of 
the City of Mexico I found inclined to doubt the existence of a glacier 
on the mountain, and even to consider it impossible. Packard, writ- 
ing in 1886,{ states that the snow-fields of Ixtaccihuatl, which extend 
along the western side of the range, are, without doubt, thin like those 
of Popocatepetl, and give rise to no extensive glaciers. It was, 
therefore, partly to determine for myself whether a glacier existed 
on the mountain, that I resolved to visit the spot where it was 
said torbe located. 
My observations enable me to assert with certainty (1) that one 
exemplary glacier exists on the western slope of Ixtaccihuatl, and (2) 
that it formerly had a much greater extent than now. 
Like Popocatepetl, the whole upper part of Ixtaccihuatl is cov- 
ered with perpetual snow. The snow line marks on an average a zone 
about 2,000 feet below the summit of the mountain, but is, of course, 
several hundred feet lower during the summer or rainy season than 
during the winter or dry season. 
While on Popocatepetl, however, the smooth surface of its coni- 
cal summit affords no depression where snow and ice can accumulate— 
and such accumulation is further hindered by the porous, ashen bed 
on which the snow lies—the upper portion of Ixtaccihuatl is furrowed 
by several great valleys which by their form and character of the 
rock bed favor the formation of glaciers. These valleys have in gen- 

*O%. cit. p. 259. 
tOPZ. cit. p. 115. 
tO%. cit. p. 121. 
