page_title: Patagonia
section_title: Physical geography
hierarchical_section_title: Patagonia / Physical geography
caption_attribution_description: עברית: פטגוניה, ארגנטינה: שחפים ומגדלור English: Patagonia, south of Argentina: in island, with lighthouse and sea birds.
context_page_description: Patagonia is a sparsely populated region at the southern end of South America, shared by Argentina and Chile. The region comprises the southern section of the Andes Mountains, lakes, fjords, and glaciers in the west and deserts, tablelands and steppes to the east. Patagonia is bounded by the Pacific Ocean on the west, the Atlantic Ocean to the east, and many bodies of water that connect them, such as the Strait of Magellan, the Beagle Channel, and the Drake Passage to the south.
  The Colorado and Barrancas rivers, which run from the Andes to the Atlantic, are commonly considered the northern limit of Argentine Patagonia. The archipelago of Tierra del Fuego is sometimes included as part of Patagonia. Most geographers and historians locate the northern limit of Chilean Patagonia at Huincul Fault, in Araucanía Region.
  At the time of the Spanish arrival, Patagonia was inhabited by multiple indigenous tribes. In a small portion of northwestern Patagonia, indigenous peoples practiced agriculture, while in the remaining territory, peoples lived as hunter-gatherers, traveling by foot in eastern Patagonia or by dugout canoe and dalca in the fjords and channels.
context_section_description: Argentine Patagonia is for the most part a region of steppe-like plains, rising in a succession of 13 abrupt terraces about 100 m (330 ft) at a time, and covered with an enormous bed of shingle almost bare of vegetation. In the hollows of the plains are ponds or lakes of fresh and brackish water. Towards Chilean territory, the shingle gives place to porphyry, granite, and basalt lavas, and animal life becomes more abundant. Vegetation is more luxuriant, consisting principally of southern beech and conifers. The high rainfall against the western Andes (Wet Andes) and the low sea-surface temperatures offshore give rise to cold and humid air masses, contributing to the ice fields and glaciers, the largest ice fields in the Southern Hemisphere outside of Antarctica.
  Among the depressions by which the plateau is intersected transversely, the principal ones are the Gualichu, south of the Río Negro, the Maquinchao and Valcheta (through which previously flowed the waters of Nahuel Huapi Lake, which now feed the Limay River), the Senguerr (spelled Senguer on most Argentine maps and within the corresponding region), and the Deseado River. Besides these transverse depressions (some of them marking lines of ancient interoceanic communication), others were occupied by either more or less extensive lakes, such as the Yagagtoo, Musters, and Colhue Huapi, and others situated to the south of Puerto Deseado in the center of the country.
  Across much of Patagonia east of the Andes, volcanic eruptions have created formation of basaltic lava plateaus during the Cenozoic. The plateaus are of different ages with the older –of Neogene and Paleogene age– being located at higher elevations than Pleistocene and Holocene lava plateaus and outcrops. 
  Erosion, which is caused principally by the sudden melting and retreat of ice aided by tectonic changes, has scooped out a deep longitudinal depression, best in evidence where in contact with folded Cretaceous rocks, which are lifted up by the Cenozoic granite. It generally separates the plateau from the first lofty hills, whose ridges are generally called the pre-Cordillera. To the west of these, a similar longitudinal depression extends all along the foot of the snowy Andean Cordillera. This latter depression contains the richest, most fertile land of Patagonia. Lake basins along the Cordillera were also gradually excavated by ice streams, including Lake Argentino and Lake Fagnano, as well as coastal bays such as Bahía Inútil.
caption: Island - seabirds and Les Eclaireurs Lighthouse in foreground with mountain rising in background
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