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The general character of the Argentine portion of Patagonia is for the most part a region of vast steppe-like plains, rising in a succession of abrupt terraces about 100 meters (330 feet) at a time, and covered with an enormous bed of shingle almost bare of vegetation. In the hollows of the plains are ponds or lakes of brackish and fresh water. Towards the Andes the shingle gives place to porphyry, granite, and basalt lavas, animal life becomes more abundant and vegetation more luxuriant, acquiring the characteristics of the flora of the western coast, and consisting principally of southern beech and conifers.
Among the depressions by which the plateau is intersected transversely, the principal are the Gualichu, south of the Rio Negro, the Maquinchau and Balcheta (through which previously flowed the waters of lake Nahuel-Huapi, which now feed the river Limay); the Senguerr, the Deseado. Besides these transverse depressions (some of them marking lines of ancient inter-oceanic communication), there are others which were occupied by more or less extensive lakes, such as the Yagagtoo, Musters, and Colhuapi, and others situated to the south of Puerto Deseado, in the centre of the country. In the central region volcanic eruptions, which have taken part in the formation of the plateau from the Tertiary period down to the present era, cover a large part with basaltic lava-caps; and in the western third more recent glacial deposits appear above the lava. There, in contact with folded Cretaceous rocks, uplifted by the Tertiary granite, erosion, caused principally by the sudden melting and retreat of the ice, aided by tectonic changes, has scooped out a deep longitudinal depression, which generally separates the plateau from the first lofty hills, the ridges generally called the pre-Cordillera, while on the west of these there is a similar longitudinal depression all along the foot of the snowy Andean Cordillera. This latter depression contains the richest and most fertile land of Patagonia.
The geological constitution is in accordance with the orographic physiognomy. The Tertiary plateau, flat on the east, gradually rising on the west, shows Upper Cretaceous caps at its base. First come Lower Cretaceous hills, raised by granite and dioritic rocks, undoubtedly of Tertiary origin, as in some cases these rocks have broken across the Tertiary beds, so rich in mammal remains; then follow, on the west, metamorphic schists of uncertain age; then quartzites appear, resting directly on the primitive granite and gneiss which form the axis of the Cordillela. Porphyritic rocks occur between the schists and the quartzites. The Tertiary deposits are greatly varied in character, and there is considerable difference of opinion concerning the succession and correlation of the beds. They are divided by Wilckensi into the following series (in ascending order)
Glaciers occupy the valleys of the main chain and some of the lateral ridges of the Cordillera, and descend to lakes San Martin, Viedma, Argentino and others in the same locality, strewing them with icebergs. In Patagonia an immense ice-sheet extended to the east of the present Atlantic coast during the first ice age, at the close of the Tertiary epoch, while, during the second glacial age in modern times, the terminal moraines have generally stopped, 30 miles in the north and 50 miles in the south, east of the summit of the Cordillera. These ice-sheets, which scooped out the greater part of the longitudinal depressions, and appear to have rapidly retreated to the point where the glaciers now exist, did not, however, in their retirement fill up with their detritus the fjords of the Cordillera, for these are now occupied by deep lakes on the east, and on the west by the Pacific channels, some of which are as much as 250 fathoms in depth, and soundings taken in them show that the fjords are as usual deeper in the vicinity of the mountains than to the west of the islands. Several of the high peaks are still active volcanoes.
In so far as its main characteristics are concerned, Patagonia seems to be a portion of the Antarctic continent, the permanence of which dates from very recent times, as is evidenced by the apparent recent emergence of the islets around Chiloe, and by the general character of the pampean formation. Some of the promontories of Chiloe are still called huapi, the Araucanian equivalent for "islands"; and this may perhaps be accepted as perpetuating the recollection of the time when they actually were islands. They are composed of caps of shingle, with great, more or less rounded boulders, sand and volcanic ashes, precisely of the same form as occurs on the Patagonian plateau. From an examination of the pampean formation it is evident that in recent times the land of the province of Buenos Aires extended farther to the east, and that the advance of the sea, and the salt-water deposits left by it when it retired, forming some of the lowlands which occur on the littoral and in the interior of the pampas, are much more recent phenomena; and certain caps of shingle, derived from rocks of a different class from those of the neighbouring hills, which are observed on the Atlantic coasts of the same province, and increase in quantity and size towards the south, seem to indicate that the caps of shingle which now cover such a great part of the Patagonian territory recently extended farther to the east, over land which has now disappeared beneath the sea, while other marine deposits along the same coasts became converted into bays during the subsequent advance of the sea. There are besides, in the neighbourhood of the present coast, deposits of volcanic ashes, and the ocean throws up on its shores blocks of basaltic lava, which in all probability proceed from eruptions of submerged volcanoes now extinct. One fact, however, which apparently demonstrates with greater certainty the existence in recent times of land that is now lost, is the presence of remains of pampean mammals in Pleistocene deposits in the bay of San Julian and in Santa Cruz. The animals undoubtedly reached these localities from the east; it is not at all probable that they advanced from the north southwards across the plateau intersected at that cime by great rivers and covered by the ice-sheet. With the exceotion of the discoveries at the inlet of Ultinia Esoeranza, which is in close communication with the Atlantic valley of Gallegos, none of these remains have been discovered in the Andean regions.
On the upper plains of Neuquen territory thousands of cattle can be fed, and the forests around Lakes Tiaful and Nahuel-Huapi yield large quantities of valuable timber. The Neuquen river is not navigable, but as its waters are capable of being easily dammed in places, large stretches of land in its valley are utilized; but the lands on each side of its lower part are of little commercial value. As the Cordillera is approached the soil becomes more fertile, and suitable districts for the rearing of cattle and other agricultural purposes exist between the regions which surround the Tromen volcano and the first ridges of the Andes. Chos Malal, the capital of the territory, is situated in one of these valleys. More to the west is the mining region, in great part unexplored, but containing deposits of gold, silver, copper and lignite. In the centre of the territory, also in the neighbourhood of the mining districts, are the valleys of Norquin and Las Lajas, the general camp of the Argentine army in Patagonia, with excellent timber in the forest on the Andean slope. The wide valleys occur near Rio Malleco, Lake Huechulafquen, the river Chimehuin, and Vega de Chapelco, near Lake Lacar, where are situated villages of some importance, such as Junin de los Andes and San Martin de los Andes. Close to these are the famous apple orchards supposed to have been planted by the Jesuits in the 17th and 18th centuries. These regions are drained by the river Collon-Cura, the principal affluent of the river Limay. Lake Lacar is now a contributary of the Pacific, its outlet having been changed to the west, owing to a passage having been opened through the Cordillera.
The Rio Negro runs along a wide transverse depression. the middle part of which is followed by the railway which runs to the settlement of Neuquen at the confluence of the rivers Limay and Neuquen. In this depression are several settlements, among them Viedma, the capital of the Rio Negro territory, Pringles, Conesa, Choelechoel and Roca. To the south of the Rio Negro the Patagonian plateau is intersected by the depressions of the Gualicho and Maquinchau, which in former times directed the waters of two great rivers (now disappeared) to the gulf of San Matias, the first-named depression draining the network of the Collon-Cura and the second the Nahuel-Huapi lake system. In 42°S there is a third broad transverse depression, apparently the bed of another great river, now perished, which carried to the Atlantic the waters of a portion of the eastern slope of the Andes, between 41° and 42°30;S.
Chubut territory presents the same characteristics as the Rio Negro territory. Rawson, the capital, is situated at the mouth of the river Chubut on the Atlantic (42°30'S). The town was founded in 1865 by a group of colonists from Wales, assisted by the Argentine government; and its prosperity has led to the foundation of other important centres in the valley, such as Treleu and Gaiman, which is connected by railway with Porto Madryn on Bahia Nueva. Here is the seat of the governor of the territory, and by 1895 the inhabitants of this part of the territory, composed principally of Argentines, Welsh and Italians, numbered 2585. The valley has been irrigated and cultivated, and produces the best wheat of the Argentine Republic. Between the Chubut and the Senguerr there are vast stretches of fertile land, spreading over the Andean region to the foot of the Cordillera and the lateral ridges of the Pre-Cordillera, and filling the basins of some desiccated lakes, which have been occupied since 1885, and farms and colonies founded upon them. The chief of these colonies is that of 16 de Octobre, formed in 1886, mainly by the inhabitants of Chubut colony, in the longitudinal valley which extends to the eastern foot of the Cordillera. Other rivers in this territory flow into the Pacific through breaches in the Cordillera, e.g. the upper affluents of the Fetaleufu, Palena and Rio Cisnes. The principal affluent of the Palena, the Carrenleufti, carries off the waters of Lake General Paz, situated on the eastern slope of the Cordillera. Rio Pico, an affluent of the same river, receives nearly the whole of the waters of the extensive undulating plain which lies between the Rio Teka and the Rio Senguerr to the east of the Cordillera, while the remainder are carried away by the affluents of Rio Jehua, viz., the Cherque, Omkel and Appeleg. This region contains auriferous drifts, but these, like the auriferous deposits, veins of galena and lignite in the mountains farther west which flank the Cordillera, have not been properly investigated. At Lake Fontana there are auriferous drifts and lignite deposits which abound in fossil plants of the Cretaceous age. The streams which form the rivers Mayo and Chalia join the tributaries of the Rio Aisen, which flows into the Pacific, watering in its course extensive and valuable districts where colonization has been initiated by Argentine settlers. Colonies have also been formed in the basin of Lakes Musters and Colhué; and on the coasts near the Atlantic, along Bahia Camarones and the Gulf of San Jorge, there are extensive farms.
The territory of Santa Cruz is arid along the Atlantic coast and in the central portion between 46° and 50°S. With the exception of certain valleys at Puerto Deseado (Port Desire) and in the transverse basins which occur as far south as Puerto San Julian, and which contain several cattle farms, few spots are capable of cultivation, the pastures being poor, water insufficient and salt lagunas fairly numerous. Puerto Deseado is the outlet for the produce of the Andean rerion situated between Lakes Buenos Aires and Pueyrredon.
Into this inlet there flowed at the time of the conquest a voluminous river, which subsequently disappeared, but returned again to its ancient bed, owing to the river Fenix, one of its affluents, which had deviated to the west, regaining its original direction. Lake Buenos Aires, the largest lake in Patagonia, measuring 120 kilometers (75 miles) in length, poured its waters into the Atlantic even in post-Glacial times by means of the river Deseado; and it is so depicted on the maps of the 17th and 18th centuries; and so too did Lake Pueyrredon, which, through the action of erosion, now empties itself westward, through the river Las Heras, into the Calen inlet of the Pacific, in 48°S.
San Julian on Puerto San Julian, where Ferdinand Magellan wintered, was the centre of a cattle farming colony, and colonists have pushed into the interior up the valley of a now extinct river which in comparatively recent times carried down to Puerto San Julian the waters of Lakes Volcan, Beigrano, Azara, Nansen, and some other lakes which now drain into the river Mayer and so into Lake San Martin. The valleys of the Rio Chico throughout their whole extent, as well as those of Lake Shehuen, afford excellent grazing, and around Lakes Belgrano, Burmeister and Rio Mayer and San Martin there are spots suitable for cultivation. In the Cretaceous hills which flank the Cordillera important lignite beds and deposits of
mineral oils have been discovered. The Rio Santa Cruz, originally
explored by Captain Fitzroy and Charles Darwin, is an important artery
of communication between the regions bordering upon the Cordillera and
the Atlantic. In Santa Cruz bay an important trade centre has been
established. But the present cattle region par excellence of Patagonia
is the department of Rio Gallegos, the farms extending from the Atlantic
to the Cordillera. Puerto Gallegos itself is an important business
centre, which bids fair to rival the Chilean colony of Punta Arenas, on
the Straits of Magellan. Owing to the produce of the cattle farms established there, the working of coal in the neighbourhood, and the export of timber from the surrounding forests, the town of Punta Arenas is in a flourishing condition. Its population in 1911 numbered about 4000. But the colonization of the western (Chilean) coast has generally failed, principally owing to the adverse climatic conditions of the Cordillera in those latitudes.
The climate is less severe than was supposed by early
travellers. The east slope is warmer than the west, especially in
summer, as a branch of the southern equatorial current reaches its
shores, whereas the west coast is washed by a cold current. At Puerto
Montt, on the inlet behind Chiloe Island. the mean annual temperature is
11C (52°F) and the average extremes 25.5C (78°F) and -1.5C
(29.5°F), whereas at Bahia Blanca near the Atlantic coast and just
outside the northern confines of Patagooia the annual temperature is 15C
(59°F) and the range much greater. At Punta Arenas, in the extreme
south, the mean temperature is 6C (43°F) and the average extremes 24.5C (76°F) and -2C (28°F). The prevailing winds are westerly, and the westward slope has a much heavier precipitation than the eastern; thus at Puerto Montt the mean annual precipitation is 246 centimeters (97 inches), but at Bahia Blanca it is 48 centimeters (19 inches). At Punta Arenas it is 56 centimeters (22 inches).
The guanaco, the puma, the zorro or Brazilian fox (Canis azarae), the zorrino or Mephitis patagonica (a kind of skunk), and the tuco-tuco or Ctenomys niagellanicus (a rodent) are the most characteristic mammals of the Patagonian plains. The guanaco roam in herds over the country and form with the rhea (Rhea americana, and more rarely Rhea darwinii) the chief means of subsistence for the natives, who hunt them on horseback with dogs and bolas. Bird-life is often wonderfully abundant. The carrancha or carrion-hawk (Polyborus tharus) is one of the characteristic objects of a Patagonian landscape; the presence of long-tailed green parakeets (Conurus cyanolysius) as far south as the shores of the strait attracted the attention of the earlier navigators; and hummingbirds may be seen flying amidst the falling snow. Of the many kinds of water-fowl it is enough to mention the flamingo, the upland goose, and in the strait the remarkable steamer duck.
Patagonia was discovered in 1520 by Ferdinand Magellan, who on his passage along the coast named many of the more striking features -- Gulf of San Matias, Cape of 11,000 Virgins (now simply Cape Virgenes), &c. By 1611 the Patagonian god Setebos (Settaboth in Pigafetta) was familiar to the hearers of the Tempest. Rodrigo de Isla, despatched inland in 1535 from San Matias by Alcazava Sotomayor (on whom western Patagonia had been conferred by the king of Spain), was the first to traverse the great Patagonian plain, and, but for the mutiny of
his men, he would have struck across the Andes to the Chilean side. Pedro de Mendoza, on whom the country was next bestowed, lived to found Buenos Aires, but not to carry his expiorations to the south. Alonzo de Camargo (1539), Juan Ladrilleros (1557) and Hurtado de Mendoza (1558) helped to make known the western coasts, and Sir Francis Drake's voyage in 1577 down the eastern coast through the strait and northward by Chile and Peru was memorable for several reasons; but the geography of Patagonia owes more to Pedro Sarmiento de Gamboa (1579-1580), who, devoting himself especially to the south-west region, made careful and accurate surveys. The settlement which he founded at Nombre de Dios and San Felipe were neglected by the Spanish government, and the latter was in such a miserable state when Thomas Cavendish visited it in 1587 that he called it Port Famine. The district in the neighbourhood of Puerto Deseado, explored by John Davis about the same period, was taken possession of by Sir John Narborough in the name of King Charles II of England in 1669. In the second half of the 18th century knowledge of Patagonia was augmented by Byron (1764-1765), S. Wallis (1766) and L.A. de Bougainville (1766); Thomas Falkner, a Jesuit who resided near forty years in those parts, published his Description of Patagonia (Hereford, 1774); Francesco Viedma founded El Carmen, and Antonio advanced inland to the Andes (1782); and Basilio Villarino ascended the Rio Negro (1782). The Adventure and Beagle expeditions under Philip King (1826-1830) and Robert Fitzroy (1832-1836) were of first-rate importance, the latter especially from the participation of Charles Darwin; but of the interior of the country nothing was observed except 200 miles of the course of the Santa Crux. Captain G.C. Musters in 1869 wandered in company with a band of Tehuelches through the whole length of the country from the strait to the Manzaneros in the north-west, and collected a great deal of information about the people and their mode of life.