In the southern part of the continent are the treeless plains of the Pampas, extending from about 20 degrees south latitude for a distance of fully two thousand miles into Patagonia, and averaging in width five hundred miles. Stretching, as do these plains, across a large portion of the South Temperate Zone, they present great varieties of climate. The northern portion is watered by the River La Plata and its tributaries. To the south of Buenos Ayres the rivers are fewer and of less extent. The north-western Pampas consist of slightly undulating and dry plains, though interspersed with vast tracts on which lofty thistles rear their heads--useful, however, as fuel to the inhabitants. Further on, to the west, is a wide-extending pastoral district; and yet beyond, reaching to the foot of the Cordilleras, the soil is well-suited for agriculture. The pastoral region is almost a dead level, with large shallow salt-lakes,--one of them measuring fifty miles in length by twenty in width. Scarcely a tree is to be found throughout this region, and but few permanent water-courses. To the north extends a salt desert for upwards of one hundred miles, with a width of two hundred miles. It is crossed by the River Salado, which, rising in the Cordilleras, falls into the Plata, to the south of which rises a number of step-like terraces, sterile during the heats of summer, but covered with verdure after the rains of spring. Huge boulders, brown grass growing in tufts, and low spine-covered bushes, diversify the surface. In this inhospitable region transitions from heat to cold are very great. Now the traveller is panting under the intense heat of the sun's rays; and anon an icy blast rushes across the plain, compelling him to draw close around his body his thick poncho, for protection against its chilling influences. Further to the south are found large swamps and lagoons, one of them having an area of one thousand square miles, its surface covered with aquatic plants. In the rainy season, the rivers, overflowing their banks, inundate the plains--leaving behind, however, a thick deposit of fertilising soil, from which, as elsewhere, rich crops are capable of being produced. Further on, to the south, the Pampas, over which the yet savage and untamed Patagonians roam, and hunt the huanacu and ostrich, is generally higher and drier.