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The Argentine Republic

CHAPTER I
THE NATURAL REGIONS OF ARGENTINA

The South-American continent is divided, from west to east, into three great zones. The lofty chains of the Andes stretch along the Pacific coast; at the foot of these are immense alluvial tablelands; further east are the level plains of the Atlantic coast. The eastern zone, the tablelands, ends southward at the mouth of the Rio de la Plata. It enters Argentine territory only in the north-east corner of the province of Misiones. Below 35° S. lat. the alluvial plains open freely upon the ocean. The position of Buenos Aires, in the threshold of the plain of the Pampas, is somewhat like that of Chicago at the beginning of the prairies; if you imagine the north-eastern States and eastern Canada struck off the map, and the sea penetrating inland as far as the Lakes.

The three essential aspects of Argentine scenery are mountain, plain, and river. The Paraná, indeed, is a whole natural region in itself, with its arms and its islands, and the ever-changing low plain over which its floods spread, as one sees it from the top of the clay barrancas (cliffs); though it is so broad that one cannot see the opposite bank. It wanders over the plain like a foreigner, an emissary from tropical America; for it has a flora of its own and tepid waters which often cause a fog over the estuary where they mingle with the waters of the sea.

From the general mass of the Argentine plains, we must set apart the region between the Paraná and the Uruguay, which Argentinians call "Mesopotamia." While æolian clays form the soil of the Pampa on the right bank of the Paraná, fluvial deposits—sands and gravel, in which it is impossible to distinguish the contribution of the Uruguay from that of the Paraná—cover a great part of Mesopotamia. The earlier beds of the rivers may be traced here, not only by the alluvial deposits they have left, but by the lagoons which still mark their course. Running waters have shaped the landscape and scooped out a system of secondary valleys, and these reflect the history of the river itself and the variations of base-level which led to alternate periods of erosion and deposit.

On the right bank, on the contrary, the Paraná has no tributaries of any importance except at the extreme north of the country. The scarcity of running water is, in fact, one of the characteristic features of the plain of the Pampas. Except in the east, along the Paraná, where a network of permanent streams develops on a comparatively impermeable and fairly humid soil, and except at the foot of the mountains, where irregular torrents and streams, swollen after a storm and scanty in the dry season, disappear, as a rule, within sight of the hills that gave them birth, there is no superficial organized drainage. As a whole, the alluvial covering of the Pampas, the upper beds of which are cut through by the barranca of the Paraná, is not of river origin; it was brought and distributed by the wind, which took the place of running water. The clay of the Pampas is a present from the winds. The increasing dryness of the climate toward the west, as one approaches the Cordillera, explains the feebleness of the erosion by water and the extent of the erosion by wind.

It is aridity, too, that gives their particular character to the Argentine Andes. They have little trace of perpetual snow, the lower limit of which approaches to within about four miles of the Bolivian frontier. There are no glaciers there; they reappear in the south only in the latitude of San Juan and Mendoza, on the flanks of the three giants of the southern Cordillera, Mercedario, Aconcagua, and Tupungato. Below the small number of steep furrows which the glaciers have carved, and usually up to the top of the mountain, there spreads what has been called, very expressively, "the zone of rubbish." In this the winter's snows, fretted by the sun in that clear atmosphere, form those multitudes of narrow pyramids which the Argentinians compare to processions of white-robed pilgrims. The underlying rock is rarely visible. It is covered with a thick cloak of rubbish, split off by the frost, which the slow-moving waters released by the melting of the snows heap up at the foot of the slopes, at the bottom of depressions. The half-buried summits are succeeded by basins of accumulation. In the valleys round the mountains there are immense beds of detritic, half-rounded shingle. The torrents have cut their way through the alluvial mass, and they flow at the foot of high terraces which mark the sites of former valleys.

The spread of colonization toward the south during the last generation has extended Argentine territory beyond the limits of these classic scenes. The Patagonian Andes differ profoundly from the Northern Andes; and the change is not more sudden than that of the climate, to which it is due. Going toward the south, one passes, almost without a break, from the Atlas Mountains to Scandinavia. The moisture increases in proportion as the mean temperature falls. The mountains are covered with snow, and the glaciers lengthen. In one part of Patagonia they still form a continuous cap, an "inland sea," concealing the rock over the entire central zone of the Cordillera; though they are only the shrunken remainder of a glacial cap which was once far more extensive. Here ice was the chief sculptor of the scenery. It has made elevated tablelands, broadened the deep valleys which cut the flank of the mountain, polished their sides, and deposited at the point where they open out the amphitheatres of the moraines, behind which the waters have accumulated and formed lakes; and these