In Argentina, on the contrary, everything speaks of the close and direct dependence of the country upon oversea markets. The soil itself bears the marks of this solidarity. It is seen in the network of the railways, the concentration of the urban population in the ports, and the distribution of the cultivated districts in concentric circles which are often limited, not by a physical obstacle, but by the cost of freightage between the productive centre and the port. Thus we get a geographical expression of facts which seem at first sight to belong to the purely economic or sociological order. CHAPTER II THE OASES OF THE NORTH-WEST AND PASTORAL LIFE IN THE SCRUB The inhabited zones of the Andes in the north-west--_Valles_, _Quebradas_, _Puna_--The irrigation of the _valles_--The historic routes--Convoys of stock--The breeding of mules and the fairs--The struggle of the breeders against drought--The Sierra de los Llanos. The whole life and wealth of the arid provinces of north-western Argentina depend upon irrigation; the water-supply definitively settles the sites of human establishments. The water resources are irregularly distributed. They are especially abundant in the south (San Juan, Mendoza, and San Rafael), where the torrents of the Cordillera are fed by the glaciers, and on the outer fringe of the hills above the Chaco, at the foot of Aconcagua, which gathers masses of cloud and rain on its flanks (Tucuman). In the intermediate district, on the contrary, in the regions of La Rioja and Catamarca, and in the interior of the hilly zone to the north-west of Tucuman, the amount of available water is small; the oases shrink into small spots far removed from each other.