The fifth region comprises the high ridge which divides the basin of the Carilaufquen from Nahuel Huapi, the water of which flows northward toward the Limay and southward toward the Chubut: successive eruptions have covered the surface with lava and ash, which at Anecon rise to a height of 6,700 feet. The granite platform which emerges in the north, at the Cerro Aspero and the Quadradito, rises to a height of 4,400 and 4,700 feet, and in some places presents a bold and rejuvenated aspect. The whole has been cut up in all directions by erosion, and it affords comparatively easy means of getting about, which the Indian tracks have followed. Below the higher slopes the valleys deepen into gorges, and these broaden out in the soft tufa and are lost at the cross-streams of lava or the outcrops of the granite. In so varied a land, with such marked differences of altitude, the winter and summer pastures are always close together. Precipitation is more plentiful than at a distance from the Cordillera; the pasturage is richer, and the size of the flock rises to 1,600 sheep to the league. The sheep pass the winter on the lower slopes, where they are sheltered from the winds and the snow. They descend to the _mallin_ when the dry season sets in and makes the soil firm. In summer they go on to the tablelands, where the pastures extend to a height of 5,000 feet. Bailey Willis, studying the improvements that might be made in the pastoral processes, concluded that the essential point was to use each pasturage in its best season, and establish a carefully considered rotation on the various lands. This system, which alone would enable them to nurse the natural resources of the scrub in the way of plants for fodder, is used to-day in only a small number of districts--in the east, where the flocks winter on the coastal plain and spend the summer on the Somuncura tableland, and in the west, round the Anecon, where the summer and winter pastures are not far from each other. The custom ought to be general. The area which ought to be reserved for winter pasture comprises the coastal plains, the whole of the low-lying district round Valcheta, and the lower part of the valleys to the south of the Carilaufquen. They are less extensive than the available summer pastures, but their capacity could be enlarged by developing the irrigated areas in the Bajo de Valcheta, and sowing lucerne in the _mallinas_ of the basin of the Carilaufquen. The low valleys round the Carilaufquen ought to be reserved for winter pasture. In the summer the sheep would be taken south to the higher-level valleys, which afford permanent pasture. From there they would spread after the melting of the snow, and after the first rains in autumn, over the high tablelands which surround them.