and passed a more agreeable night. The following morning we climbed
out again on the farther side of the canyon and skirted the eastern
slopes of Mt. Solimana. Soon the trail turned abruptly to the left,
away from our old friend Coropuna.

We wondered how long ago our mountain was an active volcano. To-day,
less than two hundred miles south of here are live peaks, like El
Misti and Ubinas, which still smolder occasionally and have been
known in the memory of man to give forth great showers of cinders
covering a wide area. Possibly not so very long ago the great
truncated peak of Coropuna was formed by a last flickering of the
ancient fires. Dr. Bowman says that the greater part of the vast
accumulation of lavas and volcanic cinders in this vicinity goes
far back to a period preceding the last glacial epoch. The enormous
amount of erosion that has taken place in the adjacent canyons and
the great numbers of strata, composed of lava flows, laid bare by
the mighty streams of the glacial period all point to this conclusion.

My saddle mule was one of those cantankerous beasts that are gentle
enough as long as they are allowed to have their own way. In her
case this meant that she was happy only when going along close to
her friends in the caravan. If reined in, while I took some notes,
she became very restive, finally whirling around, plunging and
kicking. Contrariwise, no amount of spurring or lashing with a stout
quirt availed to make her go ahead of her comrades. This morning I
was particularly anxious to get a picture of our pack train jogging
steadily along over the desert, directly away from Coropuna. Since
my mule would not gallop ahead, I had to dismount, run a couple of
hundred yards ahead of the rapidly advancing animals and take the
picture before they reached me. We were now at an elevation of 16,000