The Andes of Southern Peru / Geographical Reconnaissance along the Seventy-Third Meridian

by Isaiah Bowman

Fig. 90—Cloudiness at Chosica, July, 1889, to September, 1890. Chosica, a station on the Oroya railroad east of Lima, is situated on the border region between the desert zone of the coast and the mountain zone of yearly rains. The minimum cloudiness recorded about 11 a. m. is shown by a broken line; the maximum cloudiness, about 7 p. m., by a dotted line, and the mean for the 24 hours by a heavy solid line. The curves are drawn from data in Peruvian Meteorology, 1889-1890, Annals of the Astronomical Observatory of Harvard College, Vol. 39, Pt. 1, Cambridge, Mass., 1899.

It is an age-old strife renewed every year and limited to a narrow field of action, wonderfully easy to observe. We saw it in its most striking form at the end of the winter season in October, 1911, and for more than a day watched the dark clouds rise ominously only to melt into nothing where the desert holds sway. At night we camped beside a scum-coated pool of alkali water no larger than a wash basin. It lay in a valley that headed in the Coast Range, and carried down into the desert a mere trickle that seeped through the gravels of the valley floor. A little below the pool the valley cuts through a mass of granite and becomes a steep-walled gorge. The bottom is clogged with waste, here boulders, there masses of both coarse and fine alluvium. The water in the valley was quite incapable of accomplishing any work except that associated with solution and seepage, and we saw it in the wet season of an unusually wet year. Clearly there has been a diminution in the water supply. But time prevented us from exploring this particular valley to its head, to see if the reduction were due to a change of climate, or only to capture of the head-waters by the vigorous rain-fed streams that enjoy a favorable position on the wet seaward slopes and that are extending their watershed aggressively toward the east at the expense of their feeble competitors in the dry belt.

An early morning start enabled me to witness the whole series of changes between the clear night and the murky day, and to pass in twelve hours from the dry desert belt through the wet belt, and emerge again into the sunlit terraces at the western foot of the Coast Range. Two hours before daylight a fog descended from the hills and the going seemed to be curiously heavy for the beasts. At daybreak my astonishment was great to find that it was due to the distinctly moist sand. We were still in the desert. There was not a sign of a bush or a blade of grass. Still, the surface layer, from a half inch to an inch thick, was really wet. The fog that overhung the trail lifted just before sunrise, and at the first touch of the sun melted away as swiftly as it had come. With it went the surface moisture and an hour after sunrise the dust was once more rising in clouds around us.

We had no more than broken camp that morning when a merchant with a pack-train passed us, and shouted above the bells of the leading animals that we ought to hurry or we should get caught in the rain at the pass. My guide, who, like many of his kind, had never before been over the route he pretended to know, asked him in heaven’s name what drink in distant Camaná whence he had come produced such astonishing effects as to make a man talk about rain in a parched desert. We all fell to laughing and at our banter the stranger stopped his pack-train and earnestly urged us to hurry, for, he said, the rains beyond the pass were exceptionally heavy this year. We rode on in a doubtful state of mind. I had heard about the rains, but I could not believe that they fell in real showers!

About noon the cloud bank darkened and overhung the border of the desert. Still the sky above us was clear. Then happened what I can yet scarcely believe. We rode into the head of a tiny valley that had cut right across the coast chain. A wisp of cloud, an outlier of the main bank, lay directly ahead of us. There were grass and bushes not a half-mile below the bare dry spot on which we stood. We were riding down toward them when of a sudden the wind freshened and the cloud wisp enveloped us, shutting out the view, and ten minutes later the moisture had gathered in little beads on the manes of our beasts and the trail became slippery. In a half-hour it was raining and in an hour we were in the midst of a heavy downpour. We stopped and pastured our famished beasts in luxuriant clover. While they gorged themselves a herd of cattle drifted along, and a startled band of burros that suddenly confronted our beasts scampered out of sight in the heavy mist. Later we passed a herdsman’s hut and long before we reached him he shouted to us to alter our course, for just ahead the old trail was wet and treacherous at this time of year. The warning came too late. Several of our beasts lost their footing and half rolled, half slid, down hill. One turned completely over, pack and all, and lay in the soft mud calmly taking advantage of the delay to pluck a few additional mouthfuls of grass. We were glad to reach firmer ground on the other side of the valley.

The herdsmen were a hospitable lot. They had come from Camaná and rarely saw travelers. Their single-roomed hut was mired so deeply that one found it hard to decide whether to take shelter from the rain inside or escape the mud by standing in the rain outside. They made a little so-called cheese, rounded up and counted the cattle on clear days, drove them to the springs from time to time, and talked incessantly of the wretched rains in the hills and the delights of dry Camaná down on the coast. We could not believe that only some hours’ traveling separated two localities so wholly unlike.

The heavy showers and luxuriant pastures of the wet years and the light local rains of the dry years endow the Coast Range with many peculiar geographic qualities. The heavy rains provide the desert people at the foot of the mountains such a wealth of pasture for their burdensome stock as many oases dwellers possess only in their dreams. From near and far cattle are driven to the wet hill meadows. Some are even brought in from distant valleys by sea, yet only a very small part of the rich pastures can be used. It is safe to say that they could comfortably support ten times the number of cattle, mules, and burros that actually graze upon them. The grass would be cut for export if the weather were not so continually wet and if there were not so great a mixture of weeds, flowers, and shrubs.

Then come the dry years. The surplus stock is sold, and what remains is always maintained at great expense. In 1907 I saw stock grazing in a small patch of dried vegetation back of Mollendo, although they had to be driven several miles to water. They looked as if they were surviving with the greatest difficulty and their restless search for pasture was like the search of a desperate hunter of game. In 1911 the same tract was quite devoid of grass, and except for the contour-like trails that completely covered the hills no one would even guess that this had formerly been a cattle range. The same year, but five months later, a carpet of grass, bathed in heavy mist, covered the soil; a trickle of water had collected in pools on the valley floor; several happy families from the town had laid out a prosperous-looking garden; there were romping children who showed me where to pick up the trail to the port; on every hand was life and activity because the rains had returned bringing plenty in their train. I asked a native how often he was prosperous.

“Segun el temporal y la Providencia” (according to the weather and to Providence), he replied, as he pointed significantly to the pretty green hills crowned with gray mist.