Zona Sur

Geography

Although many lakes can be found in the Andean and coastal regions of central Chile, the south (Sur de Chile) has the country's most lakes. Southern Chile stretches from below the Río Bío-Bío at about 37° south latitude to below Isla de Chiloé at about 43.4° south latitude. In this lake district of Chile, the valley between the Andes and the coastal range is closer to sea level, and the hundreds of rivers that descend from the Andes form lakes, some quite large, as they reach the lower elevations. They drain into the ocean through other rivers, some of which (principally the Calle-Calle River, which flows by the city of Valdivia) are the only ones in the whole country that are navigable for any stretch. The Central Valley's southernmost portion is submerged in the ocean and forms the Golfo de Ancud. Isla de Chiloé, with its rolling hills, is the last important elevation of the coastal range of mountains.

The lakes in this region are remarkably beautiful. The snow-covered Andes form a backdrop to clear blue or even turquoise waters, as at Lago Todos los Santos. The rivers that descend from the Andes rush over volcanic rocks, forming numerous white-water sections and waterfalls. Some sections still consist of old-growth forests, and in all seasons, but especially in the spring and summer, there are plenty of wildflowers and flowering trees. The pastures in the northernmost section, around Osorno, are well suited for raising cattle; milk, cheese, and butter are important products of that area. All kinds of berries grow in the area, some of which are exported, and freshwater farming of various species of trout and salmon has developed, with cultivators taking advantage of the abundant supply of clear running water. The lumber industry is also important. A number of tourists, mainly Chileans and Argentines, visit the area during the summer.

In terms of tectonics at Zona Sur the South American Plate is experiencing a long-term ENE-WSW shortening. This shortening is accommodated by strike-slip faults. The details of this pattern show significant local variations.

Climate

The climate of Southern Chile is rainy with a Mediterranean precipitation pattern. The windward slopes of the Chilean Coast Range and the Andes receive up to 3000–5000 mm of precipitation annually. Behind the Chilean Coast range there is a weak rain shadow while behind the Andes, in Argentina, precipitation drops sharply. The zone lies in the mid-latitudes and is strongly influenced by the Westerlies. During the summer the South Pacific High moves into the area.

Soils

The main agricultural soils are; red clay soil (rojo arcillosos, ultisols), trumao and ñadi. Some red clay soils are planted with Eucalyptus globulus. In the middle course of Bío Bío River, in the northern part of Zona Sur, soils are sandy with a coarsening trend towards the Andes. Soils of the Chilean Coast Range are mostly derived from metamorphic rock. These soils are usually poor in phosphorus, potassium and have toxic levels of aluminium. Often, these soils have poor drainage and their thickness is highly variable even at scale of tens of meters.