1894 
Ameoameoa 
(Mexico) 
January 
the lower border of the glaciers. Enough were present to cut out the 
hills and round some of the summits while the dotrital mud flowed down 
and joined with that of Iztacoihuatl in Idle Valley of Aaaeea or built up 
the series of foothills which lie between 8,500 and 9,500 feet along the 
west and northwest slope of this mountain. These detrital foothills 
also flank the southwest base of Iztacoihuatl at the same altitude but 
are much larger. They form rounded bosses along the base of the moun¬ 
tains with occasional spurs and cliffs of lava or trachyte showing along 
the canons cut through by the water, There is no sign of glacial action 
of ary kind on the sides of Popocatepetl above the level of the ridge on 
which it is situated and it is evident that this peak has been built up 
over the summit of the ridge since the time of idle glacial action there, 
The loose lava and ashes lie upon the mountain side and no signs of ero¬ 
sion more than that caused by water are visible on the north and north¬ 
west slopes at least. 
t , 
The summit of Popocatepetl is very steep on the east, south, and 
west sides and is nearly if not quite inaccessible there. On the north 
and northeast sides is the least steepjfor this I noted a reason when 
making my descent. In early morning the surface of the slope of volcanic 
ashes just below the snot? was frozen solid. At midday the surface melted 
a little and the water fTcm lower border of snow trickled dorm slowly 
until a large amount of the loose surface ashes and gravel and pumice be¬ 
came liquified. It would then start suddenly down the slope with a 
curious low hissing noise from the grinding together of the small rough 
fragments of lava. Sometimes these miniature avalanches of mud ran only 
a few yards but many of them ran down hundreds of feet and carried great 
quantities of the ashes and gravel down the slope until the excess of 
moisture being taken up by the ground over which it passed the mud finally 
came to a standstill as a broad fan-shaped bed some inches thiok. In a 
198 
