CHAPTER XVI.VIENTE DE ZONDA.
In a preceding chapter I made reference to theviente de zonda, or zonda wind; and as the history of it is imperfectly known in the northern continent, I will here speak of it to some extent.
Theviente de zondamay be called a local wind, as it blows only in the vicinity of the province of San Juan, the town where the following observations were made.
San Juan, the capital of the province, lies at the eastern base of the Andes, three or four leagues distant from the outer sierra, south latitude 31° 4′ (Molina), longitude 68° 57′ west (Arrowsmith). Behind the first range in a valley are four or five farms, which constitute the hamlet of Zonda, from which the wind is named. It blows at all seasons, though during July and August (midwinter) it is most frequent. This wind is hot and parching to the skin, and brings with it clouds of dust and fine sand.
All persons leave their work, and seek refuge in their houses, while frequently the huts of the gauchos are blown down by the force of the wind. Most persons are troubled with severe headaches. Those who have been suffering from diseases of the heart find theircomplaints greatly aggravated, and frequently there are cases of sudden death. Three or four years since, five persons fell dead during thezondasin the month of August. The wind lasts sometimes two or three hours; at other times, forty-eight hours, though this long duration is rare. While thezondasis at its height, a few puffs of cold air from the south announce a change, and immediately the weather-cock veers from east and west to north and south, and a cold wind, equally as strong as the hotzonda, then prevails from the south. All nature is refreshed by the change, and men resume their abandoned labors.
In searching through the works of the very few authors who have visited the interior of the Argentine states (all but one or two of whom were Europeans), I find that only one mentions the existence of this phenomenon; and he did not, probably, visit the town where my observations were made, which locality is considered by the natives as the northern limit of thezondas.
John Miers, the author of an interesting work on the Provinces of La Plata and Chili, remained a short time in Mendoza. He states that this southern locality is annoyed by winds that blow during the summer months from the valley of Zonda, and notes the fact that two dark clouds came from the north-west, and hovered over the town during the greater part of the night, and in the morning everything that had been exposed to the air was covered with fine sand, which was of a light gray color, and slightly magnetic. It was Miers’s opinion that “asouffrière, or active volcano,” existed to the northward of San Juan, fromwhich the hurricanes and showers of sand originated. HadMr.Miers visited San Juan, his view of the position of the volcano would, undoubtedly, have been changed; for though thezondasreach Mendoza to the south, the direction of the wind when it strikes that place differs from the line it follows when it rushes with violence upon the northern town. At San Juan it comes due west from the Andes. Hence the starting-point of thezondacannot be to the north of the town, as Miers conjectured. According to the account of the natives, thezondaof San Juan does not cover a broader space than ten or fifteen miles after it leaves the sierra of Zonda.
Taking this into consideration, in connection with Miers’s statement that the Mendozazondacomes from the north-west, differing, as it will be seen, four points from the northern town, we may infer that the Mendoza and San Juanzondasdo not blow at the same time. If this is true, it is an interesting fact, showing that this peculiar wind does not always follow the same track.
Miers further states that these are summer winds in Mendoza. From personal observation, and by reliable accounts of educated San Juaninos, I found that they were more particularly the winter winds; at least they are more frequent during that season. Invalids suffering from pneumonical diseases and complaints affecting the heart and liver, anticipate the month of August (midwinter) with consternation, and their anxiety is not quieted until they have passed through the dreaded ordeal.
While passing the winter in San Juan, I noted thecourses of upwards of twentyzondas. Some were of short duration; others lasted eighteen or twenty hours.
During the latter part of August, as I was standing upon the saline desert, a few miles east of San Juan, my attention was attracted by a cloud of dust that appeared to roll through the air as it approached me. I started for a shelter, and had hardly reached it when thezondaswept past, filling the air with fine yellow sand. The temperature of the previously sultry atmosphere suddenly rose many degrees, and the occupants of the neighboring huts were affected with severe headaches. I noted, with a compass, the course of the wind, which was west. All night and through the following day and night, the wind continued blowing with undiminished force. Each hour the vane beside the hut was consulted, and the same course as at first was always observed. A few hours before the wind ceased the sand showers were exhausted. The greatest heat was during the first few hours; and this is always the case if thezondacommences during the day. After continuing for thirty-six hours the change came. It was instantaneous. The hot wind seemed cut off at right angles by a cold wind from the south. The change could not have occupied more than forty seconds. The south wind lasted twenty hours, and was as violent as the hotzonda. In speaking of the Mendozazondas, Miers does not mention the succession of the south wind. It is easy to comprehend that, after so large an area has become filled with heated air, the effect will be felt in the cooler regions of the south, and a strong current from that direction will rush in to restore the atmospheric equilibrium. Hence the cause of the south wind succeeding thezonda.
Miers believed that the origin of thezondaswas volcanic, and a corroboration of his views is found in the work of Sir Woodbine Parish, in which he states that the volcano Penguenes, which is situated about one hundred miles south-west from Mendoza, and reaches an altitude of nearly fifteen thousand feet above the level of the sea, emits clouds of ashes and pumice-dust. This dust is carried by the winds as far as Mendoza, but these clouds do not strike the town with the force of the San Juanzonda. The pumice-dust isbornealong by variable winds. From this fact we may infer that the fine sand of thezondascomes from a similar source. The most important question is,Where originates the hot and parching wind that always accompanies, and is peculiar to, the zondas?The old guides, who are familiar with the valleys of the Andes, informed me that these winds blow from off the main snow-clad ridge of that great chain of mountains, and expressed their surprise at the fact “that from a cold region comes a burning wind.”
Strong and steady winds generally follow a direct line. This fact is characteristic of thezondas. If Miers’s conjecture be true regarding the origin of these winds, the position of the volcano, orsouffrière, might be found by observing the following suggestion, bearing in mind that the Mendoza wind comes from thenorth-west, and the San Juanzondafrom thewest. That point where two lines—one running west from the northern town, the othernorth-westfrom the southern town—will intersect, is the starting-point of the sand clouds, if not of the accompanying hot wind.
Looking upon the map of South America, we find in the Cordillera of the Andes, between the latitudes of San Juan and Mendoza, four peaks marked as doubtful volcanoes: Limari, directly west of San Juan; Chuapu, thirty miles farther south; and near the half-way point of the two towns, Ligua. To the north of west of Mendoza stands prominent the lofty Aconcagua, that has been estimated by two English captains to have an elevation of twenty-three thousand nine hundred feet. The point of intersection of the west and north-westzondalines is in the vicinity of Limari and Chuapu, and, if not either of these, thezondavolcano is a near neighbor to them.