Narrative of the surveying voyages of His Majesty's Ships Adventure and Beagle, Vol. 3 [of 3] · Charles Darwin
PASSAGE OF CORDILLERA.
On several of the patches of perpetual snow, I found the _Protococcus nivalis_, or red snow, so well known from the accounts of Arctic navigators. My attention was called to the circumstance by observing the footsteps of the mules stained a pale red, as if their hoofs had been slightly bloody. I at first thought it was owing to dust blown from the surrounding mountains of red porphyry; for from the magnifying power of the crystals of snow, the groups of these atom-like plants appeared like coarse particles. The snow was coloured only where it had thawed very rapidly, or had been accidentally crushed. A small portion of it rubbed on paper communicated a faint rose tinge, mingled with a little brick red. I placed some of the snow between the leaves of my pocket-book, and a month afterwards examined with care the pale discoloured patches on the paper. The specimens, when scraped off, were of a spherical form, with a diameter of the thousandth of an inch. The central part consists of a blood-red substance, surrounded by a colourless bark. When living on the snow they are collected in groups, many lying close together; I overlooked, however, the thin couch of gelatinous matter on which they are said to rest.[6] The dried specimens placed in any fluid, as water, spirits of wine, or dilated sulphuric acid, were acted on in two different ways: sometimes an expansion was caused, at others a contraction. The central part after immersion invariably appeared as a drop of red oily fluid, containing a few most minute granules; and these probably are the germs of new individuals.
As I before remarked, the wind on the crest of the Peuquenes is generally impetuous and very cold. It is said to blow steadily from the westward or Pacific side: a circumstance which is likewise mentioned by Dr. Gillies.[7] As these observations apply chiefly to the summer season (when the passes are frequented), we must consider this wind, as an upper and return current. The Peak of Teneriffe, with a less elevation, and situated in lat. 28°, in like manner falls within the return stream. At first it appears rather surprising, that the trade-wind along the northern parts of Chile, and on the coast of Peru, should blow in so very southerly a direction as it does; but when we reflect, that the Cordillera, running in a north and south line, intercepts, like a great wall, the entire depth of the lower atmospheric current, we can easily see, that the trade-wind must be drawn northward, following the line of mountains, towards the equatorial regions, and thus lose part of that easterly movement which it otherwise would have gained from the rotation of the world. At Mendoza, on the eastern foot of the Andes, the climate is said to be subject to long calms, and to frequent though false appearances of gathering rain-storms: we may imagine that the wind, which coming from the eastward is thus banked up by the line of mountains, would become stagnant and irregular in its movements.
Having crossed the Peuquenes, we descended into the mountainous country, intermediate between the two ranges, and then took up our quarters for the night. The elevation was probably not much under 11,000 feet, and the vegetation in consequence exceedingly scanty. The root of a small scrubby plant served as fuel, but it made a miserable fire, and the wind was piercingly cold. Being quite tired with my day’s work, I made up my bed as quickly as I could, and went to sleep. About midnight I observed the sky became suddenly clouded: I awakened the arriero to know if there was any danger of bad weather; but he said that without thunder and lightning there was no risk of a heavy snow-storm. The peril is imminent, and the difficulty of subsequent escape great, to any one overtaken by bad weather between the two Cordillera. A certain cave offers the only place of refuge: Mr. Caldcleugh, who crossed on this same day of the month, was detained there for some time by a heavy fall of snow, as is related in his travels. Casuchas, or houses of refuge, have not been built in this pass as in that of Uspallata, and therefore, during the autumn, the Portillo is little frequented. I may here remark, that within the main Cordillera rain never falls, for during the summer, the sky is cloudless, and in winter snow-storms alone occur.
At the place where we slept, water necessarily boiled, from the diminished pressure of the atmosphere, at a much lower temperature than it does in a less elevated country; the case being the converse of that of a Papin’s digester. In consequence of this, the potatoes, after remaining for some hours in the boiling water, were nearly as hard as ever. The pot was left on the fire all night, and next morning it was boiled again, but yet the potatoes were not cooked. I found out this, by overhearing my two companions discussing the cause; they had come to the simple conclusion, “that the cursed pot (which was a new one) did not choose to boil potatoes.” MARCH 22D.--After eating our potato-less breakfast, we travelled across the intermediate tract, to the foot of the Portillo range. In the middle of summer cattle are brought up here to graze; but they had now all been removed; even the greater number of the guanacoes had decamped, knowing well, that, if overtaken by a snow-storm, they would be caught in a trap. We had a fine view of a mass of mountains called Tupungato, the whole clothed with unbroken snow. From one peak my arriero said he had once seen smoke proceeding; and I thought I could distinguish the form of a large crater. In the maps Tupungato figures as a single mountain; this Chileno method of giving one name to a tract of mountains is a fruitful source of error. In the region of snow there was a blue patch, which no doubt was a glacier;--a phenomenon that has been said not to occur in these mountains.
Now commenced a heavy and long climb, similar to that up the Peuquenes. Bold conical hills of red granite rose on each hand; and in the valley there were several broad fields of perpetual snow. These frozen masses, during the process of thawing, had in some parts assumed the form of pinnacles or columns, which, as they were high and close together, caused some difficulty on account of the cargo mules. This structure in frozen snow was long since observed by Scoresby in the icebergs near Spitzbergen, and lately, with more care, by Colonel Jackson[8] on the Neva. On one of these columns of ice a frozen horse was exposed, sticking as on a pedestal, but with its hind legs straight up in the air. To account for its strange position, we must suppose that the animal fell with its head downward into a hole, when the stratum was continuous, and that afterwards the surrounding parts were removed by the thaw.
When nearly on the crest of the Portillo, we were enveloped in a cloud which was falling, under the form of minute frozen spicula. This was very unfortunate, as it continued the whole day, and quite intercepted our view. The pass takes its name of Portillo from a narrow cleft or doorway on the highest ridge, through which the road passes. From this point, on a clear day, those vast plains which extend from the base of the mountains towards the Atlantic can be seen. We descended to the upper limit of vegetation, and found good quarters for the night under the shelter of some large fragments of rock. We here met some passengers, who made anxious inquiries about the state of the road. Shortly after it was dark, the clouds suddenly cleared away; and the effect was quite magical. The great mountains, bright with the full moon, seemed impending over us on all sides, as if we had been buried at the bottom of some deep crevice. One morning also, very early, I witnessed the same striking effect. As soon as the clouds were dispersed, it froze severely; but as there was no wind, we slept very comfortably.
The increased brilliancy of the moon and stars at this elevation, owing to the perfect transparency of the atmosphere, was very remarkable. Travellers having observed the difficulty of judging heights and distances amidst lofty mountains, have generally attributed it to the absence of objects of comparison. It appears to me that it is fully as much owing to this transparency, confounding different distances, and partly, likewise, to the novelty of an unusual degree of fatigue arising from a little exertion,--habit being thus opposed to the evidence of the senses. I am sure that this extreme clearness of the air gives a peculiar character to the landscape; all objects appearing to be brought nearly into one plane, as in a drawing or panorama. The transparency is, I presume, owing to the equable and nearly perfect state of atmospheric dryness. The latter quality was shown by the manner in which woodwork shrunk (as I soon found by the trouble my geological hammer gave me); by articles of food, such as bread and sugar, becoming extremely hard; and by the preservation of the skin and parts of the flesh of the beasts, which perish on the road. To the same cause we must attribute the singular facility with which electricity is excited. My flannel-waistcoat, when rubbed in the dark, appeared as if it had been washed with phosphorus;--every hair on a dog’s back crackled;--even the linen sheets, and leathern straps of the saddle, when handled, emitted sparks.
MARCH 23D.--The descent on the eastern side of the Cordillera is much shorter or steeper than on the Pacific side; in other words, the mountains rise more abruptly from the plains, than from the alpine country of Chile. A level and brilliantly white sea of clouds was extended beneath our feet, and thus shut out the view of the equally level Pampas. We soon entered the band of clouds, and did not again emerge from it that day. About noon, finding pasture for the animals and bushes for firewood, in a part of the valley called Los Arenales, we stopped for the night. This was near the uppermost limit of bushes, and the elevation, I suppose, was between seven and eight thousand feet.
I was very much struck with the marked difference between the vegetation of these eastern valleys and that of the opposite side: yet the climate, as well as the kind of soil, is nearly identical, and the difference of longitude very trifling. The same remark holds good with the quadrupeds, and in a lesser degree with the birds and insects. We must except certain species which habitually or occasionally frequent elevated mountains; and in the case of the birds, certain kinds, which have a range as far south as the Strait of Magellan. This fact is in perfect accordance with the geological history of the Andes; for these mountains have existed as a great barrier, since a period so remote that whole races of animals must subsequently have perished from the face of the earth. Therefore, unless we suppose the same species to have been created in two different countries, we ought not to expect any closer similarity between the organic beings on opposite sides of the Andes, than on shores separated by a broad strait of the sea. In both cases we must leave out of the question those kinds which have been able to cross the barrier, whether of salt water or solid rock.[9]
A great number of the plants and animals were absolutely the same, or most closely allied with those of Patagonia. We here have the agouti, bizcacha, three species of armadillo, the ostrich, certain kinds of partridges, and other birds, none of which are ever seen in Chile, but are the characteristic animals of the desert plains of Patagonia. We have likewise many of the same (to the eyes of a person who is not a botanist) thorny stunted bushes, withered grass, and dwarf plants. Even the black slowly-crawling beetles are closely similar, and some, I believe, on rigorous examination, absolutely identical. It had always been a subject of regret to me, that we were unavoidably compelled to give up the ascent of the St. Cruz river before reaching the mountains. I always had a latent hope of meeting with some great change in the features of the country; but I now feel sure, that it would only have been following the plains of Patagonia up an ascent. MARCH 24TH.--Early in the morning I climbed up a mountain on one side of the valley, and enjoyed a far-extended view over the Pampas. This was a spectacle to which I had always looked forward with interest, but I was disappointed. At the first glance there was a strong resemblance to a distant view of the ocean, but in the northern parts many irregularities in the surface were soon distinguishable. The most striking feature in the scene consisted of the rivers, which, facing the rising sun, glittered like silver threads, till lost in the immensity of the distance.
In the middle of the day, we descended the valley, and reached a hovel, where an officer and three soldiers were posted to examine passports. One of these men was a thorough-bred Pampas Indian. He was kept much for the same purpose as a bloodhound, to track out any person who might pass by secretly, either on foot or horseback. Some years ago, a passenger had endeavoured to escape detection, by making a long circuit over a neighbouring mountain; but this Indian, having by chance crossed his track, followed it for the whole day, over dry and very stony parts, till at last he came on his prey hidden in a gully. We here heard that the silvery clouds, which we had admired from the bright region above, had poured down torrents of rain. The valley from this point gradually opened, and the hills became mere water-worn hillocks compared to the giants behind. It then expanded into a gently-sloping plain of shingle, covered with low trees and bushes. This talus, although it looked of little breadth, must be nearly ten miles wide, before it blends into the apparently dead level Pampas. We had already passed the only house in this neighbourhood, the Estancia of Chaquaio; and at sunset we pulled up in the first snug corner, and there bivouacked.
MARCH 25TH.--I was reminded of the Pampas of Buenos Ayres, by seeing the disk of the rising sun, intersected by an horizon, level as that of the ocean. During the night a heavy dew had fallen, a fact we did not experience within the Cordillera. The road proceeded for some distance due east across a low swamp; then meeting the dry plain, it turned to the north towards Mendoza. The distance is two very long days’ journey. Our first day’s journey was called fourteen leagues to Estacado, and the second seventeen to Luxan, near Mendoza. The whole distance is over a level desert plain, with not more than two or three houses. The sun was exceedingly powerful, and the ride devoid of all interest. There is very little water in this “traversia,” and in our second day’s journey, we found only one little pool. The water flowing from the mountains is small in quantity and soon becomes absorbed by the dry and porous soil; so that, although we travelled at the distance of only ten or fifteen miles from the outer range, we did not cross a single stream. In many parts the ground was incrusted with a saline efflorescence; hence we had the same salt-loving plants, common near Bahia Blanca. The landscape has one character from the Strait of Magellan along the whole eastern coast of Patagonia to the Rio Colorado; and it appears that the same kind of country extends northerly in a sweeping line as far as San Luis, and perhaps even further. To the eastward of this line, lies the basin of the comparatively damp and green plains of Buenos Ayres. The former country, including the sterile traversia of Mendoza and Patagonia, consists of a bed of shingle, worn smooth, and accumulated by the waves of a former sea; while the formation of the Pampas (plains covered by thistles, clover, and grass) is due to the estuary mud of the Plata, deposited under a different condition of circumstances.
After our two days’ tedious journey, it was refreshing to see in the distance the rows of poplars and willows growing around the village and river of Luxan. Shortly before we arrived at this place, we observed to the southward a ragged cloud of a dark reddish-brown colour. For some time, we had no doubt but that it was thick smoke proceeding from some great fire on the plains. Soon afterwards we found it was a pest of locusts.[10] The insects overtook us, as they were travelling northward, by the aid of a light breeze, at the rate, I should suppose, of ten or fifteen miles an hour. The main body filled the air from a height of twenty feet, to that, as it appeared, of two or three thousand above the ground. The noise of their approach was that of a strong breeze[11] passing through the rigging of a ship. The sky seen through the advanced guard appeared like a mezzotinto engraving, but the main body was impervious to sight; they were not, however, so thick, but that they could escape from a stick moved backward and forward. When they alighted they were more numerous than the leaves in a field, and changed the green into a reddish colour: the swarm having once alighted, the individuals flew from side to side in any direction. The locusts are not an uncommon pest in this country: already during the season, several smaller swarms had come up from the sterile plains[12] of the south; and many trees had been entirely stripped of their leaves. Of course this swarm cannot even be compared to those of the eastern world, yet it was sufficient to make the well-known descriptions of their ravages more intelligible. I have omitted, perhaps, the most striking part of the scene,--the vain attempts of the poor cottagers to turn the stream aside. Many lighted fires and with the smoke, with shouts and waving of branches, they endeavoured to avert the attack.
We crossed the Luxan, which is a river of considerable size, though its course towards the sea-coast is very imperfectly known. It is even doubtful whether, in passing over the plains, it is evaporated, or whether it forms a tributary of the Sauce or Colorado. We slept in the village, which is a small place surrounded by gardens, and forms the most southern part, that is cultivated, of the province of Mendoza; it is five leagues south of the capital. At night I experienced an attack (for it deserves no less a name) of the _Benchuca_ (a species of Reduvius) the great black bug of the Pampas. It is most disgusting to feel soft wingless insects, about an inch long, crawling over one’s body. Before sucking they are quite thin, but afterwards become round and bloated with blood, and in this state they are easily crushed. They are also found in the northern parts of Chile and in Peru. One which I caught at Iquique was very empty. When placed on the table, and though surrounded by people, if a finger was presented, the bold insect would immediately draw its sucker, make a charge, and if allowed, draw blood. No pain was caused by the wound. It was curious to watch its body during the act of sucking, as it changed in less than ten minutes, from being as flat as a wafer to a globular form. This one feast, for which the benchuca was indebted to one of the officers, kept it fat during four whole months; but, after the first fortnight, the insect was quite ready to have another suck.
MARCH 27TH.--We rode on to Mendoza. The country was beautifully cultivated, and resembled Chile. This neighbourhood is celebrated for its fruit; and certainly nothing could appear more flourishing than the vineyards and the orchards of figs, peaches, and olives. We bought watermelons nearly twice as large as a man’s head, most deliciously cool and well-flavoured, for a halfpenny apiece; and for the value of threepence, half a wheelbarrowful of peaches. The cultivated and enclosed part of this province is very small; there is little more than that which we passed through between Luxan and the capital. The land, as in Chile, entirely owes its fertility to artificial irrigation; and it is really wonderful to observe how abundantly productive a barren traversia is rendered by this simple process. We staid the ensuing day in Mendoza. The prosperity of the place has much declined of late years. The inhabitants say “it is good to live in, but very bad to grow rich in.” The lower orders have the lounging, reckless manners of the Gauchos of the Pampas; and their dress, riding gear, and habits of life, are nearly the same. To my mind the town had a stupid forlorn aspect. Neither the boasted alameda, nor the scenery, is at all comparable to that of Santiago; but to those who have just crossed the unvaried savannahs of grass, on their road from Buenos Ayres, the gardens and orchards must appear delightful. Captain Head, speaking of the inhabitants, says, “They eat their dinners, and it is so very hot, they go to sleep--and could they do better?” I quite agree with Captain Head: the happy doom of the Mendozinos is to eat, sleep, and be idle.
MARCH 29TH.--We set out on our return to Chile by the Uspallata pass to the northward of Mendoza. We had to cross a long and most sterile traversia of fifteen leagues. The soil in parts was absolutely bare, in others covered by numberless dwarf cacti, armed with formidable spines, and called by the inhabitants “little lions.” There were also a few low bushes. Although the plain is elevated about three thousand feet above the sea, the sun was very powerful; this, and the clouds of impalpable dust, rendered the travelling extremely irksome. Our course during the day lay nearly parallel to the mountains, but gradually approaching them. Before sunset we entered one of the wide valleys, or rather bays, which open on the plain: this soon narrowed into a ravine, and a little higher up the house of the Villa Vicencio was situated. As we had ridden all day without a drop of water, both ourselves and our animals were very thirsty, and we looked out anxiously for the stream which flows down this valley. It was curious to observe how gradually the water made its appearance: on the plain the course was quite dry; by degrees it became a little damper; then puddles of water were formed; these soon became connected, and at Villa Vicencio there was a nice little rivulet.
30TH.--The solitary hovel which bears the imposing name of Villa Vicencio, has been mentioned by every traveller who has crossed the Andes. I staid here, and at some neighbouring mines, during the two succeeding days. The geology of the surrounding country is very curious. The Uspallata range is separated from the true Cordillera by a long narrow plain or basin, like those so often mentioned in Chile, but with an altitude of about six thousand feet. The range consists of various kinds of submarine lava, alternating with volcanic sandstones and other remarkable sedimentary deposits; the whole having a very close resemblance to some of the newer horizontal beds on the shores of the Pacific. From this resemblance I expected to find silicified wood, which is generally characteristic of those formations. I was gratified in a very extraordinary manner. In the central part of the range, at an elevation probably of seven thousand feet, on a bare slope, I observed some snow-white projecting columns. These were petrified trees, eleven being silicified, and from thirty to forty converted into coarsely-crystallized white calcareous spar. They were abruptly broken off; the upright stumps projecting a few feet above the ground. The trunks measured from three to five feet each in circumference. They stood a little way apart from each other, but the whole formed one distinct group. Mr. Robert Brown has been kind enough to examine the wood: he says it is coniferous, and that it partakes of the character of the Araucarian tribe (to which the common South Chilian pine belongs), but with some curious points of affinity with the yew. The volcanic sandstone in which they were embedded, and from the lower part of which they must have sprung, had accumulated in successive thin layers around their trunks; and the stone yet retained the impression of the bark.
Text from Project Gutenberg, public domain in the United States.