Inca Land - Explorations in the Highlands of Peru | Page 6

October, Tucker, Hinckley, Corporal Gamarra and I left
Arequipa; Watkins followed a week later. The first stage of the journey
was by train from Arequipa to Vitor, a distance of thirty miles. The
arrieros sent the cargo along too. In addition to the food-boxes we
brought with us tents, ice axes, snowshoes, barometers, thermometers,
transit, fiber cases, steel boxes, duffle bags, and a folding boat. Our
pack train was supposed to have started from Arequipa the day before.
We hoped it would reach Vitor about the same time that we did, but
that was expecting too much of arrieros on the first day of their journey.
So we had an all-day wait near the primitive little railway station.
We amused ourselves wandering off over the neighboring pampa and
studying the médanos, crescent-shaped sand dunes which are common
in the great coastal desert. One reads so much of the great tropical
jungles of South America and of wellnigh impenetrable forests that it is
difficult to realize that the West Coast from Ecuador, on the north, to
the heart of Chile, on the south, is a great desert, broken at intervals by
oases, or valleys whose rivers, coming from melting snows of the
Andes, are here and there diverted for purposes of irrigation. Lima, the
capital of Peru, is in one of the largest of these oases. Although
frequently enveloped in a damp fog, the Peruvian coastal towns are
almost never subjected to rain. The causes of this phenomenon are easy
to understand. Winds coming from the east, laden with the moisture of
the Atlantic Ocean and the steaming Amazon Basin, are rapidly cooled
by the eastern slopes of the Andes and forced to deposit this moisture
in the montaña. By the time the winds have crossed the mighty
cordillera there is no rain left in them. Conversely, the winds that come
from the warm Pacific Ocean strike a cold area over the frigid
Humboldt Current, which sweeps up along the west coast of South
America. This cold belt wrings the water out of the westerly winds, so
that by the time they reach the warm land their relative humidity is low.

To be sure, there are months in some years when so much moisture
falls on the slopes of the coast range that the hillsides are clothed with
flowers, but this verdure lasts but a short time and does not seriously
affect the great stretches of desert pampa in the midst of which we now
were. Like the other pampas of this region, the flat surface inclines
toward the sea. Over it the sand is rolled along by the wind and finally
built into crescent-shaped dunes. These médanos interested us greatly.
The prevailing wind on the desert at night is a relatively gentle breeze
that comes down from the cool mountain slopes toward the ocean. It
tends to blow the lighter particles of sand along in a regular dune,
rolling it over and over downhill, leaving the heavier particles behind.
This is reversed in the daytime. As the heat increases toward noon, the
wind comes rushing up from the ocean to fill the vacuum caused by the
rapidly ascending currents of hot air that rise from the overheated
pampas. During the early afternoon this wind reaches a high velocity
and swirls the sand along in clouds. It is now strong enough to move
the heavier particles of sand, uphill. It sweeps the heaviest ones around
the base of the dune and deposits them in pointed ridges on either side.
The heavier material remains stationary at night while the lighter
particles are rolled downhill, but the whole mass travels slowly uphill
again during the gales of the following afternoon. The result is the
beautiful crescent-shaped médano.

About five o'clock our mules, a fine-looking lot--far superior to any
that we had been able to secure near Cuzco--trotted briskly into the
dusty little plaza. It took some time to adjust the loads, and it was
nearly seven o'clock before we started off in the moonlight for the oasis
of Vitor. As we left the plateau and struck the dusty trail winding down
into a dark canyon we caught a glimpse of something white
shimmering faintly on the horizon far off to the northwest; Coropuna!
Shortly before nine o'clock we reached a little corral, where the mules
were unloaded. For ourselves we found a shed with a clean,
stone-paved floor, where we set up our cots, only to be awakened many
times during the night by passing caravans anxious to avoid the terrible
heat of the desert by day.

------ FIGURE
Mt. Coropuna from the Northwest ------
Where the oases are only a few miles apart one often travels by day, but
when crossing the desert is a matter of eight or ten hours' steady
jogging