of "Litoral Department". This decision was disputed by the Chilean Government and has been a source of conflict until present times. Chile claimed that according to the Uti possidetis of the Spanish crown, the coastal region belong to them and their territory bordered directly with Peru. Chileans explorers such as Juan López and José Santos Ossa discovered rich nitrate and guano deposits which produced a massive Chilean colonization of the coastline. Friction between the new settlers from both countries grew until 1879 when the War of the Pacific erupted. Antofagasta was permanently annexed by the Chilean government at the end of the war. Colonization by Chileans followed mainly from Norte Chico (the contemporary regions of Atacama and Coquimbo, also known as the III and IV regions), into the new territories of Antofagasta and Tarapacá, known as Norte Grande. In the early 20th century the region became a significant base of Chile's union-organizing movements. It continued to depend economically on the nitrate-extraction industry until its replacement by copper mining. Two of the largest and richest open pit mines in the world are located inland from Antofagasta: La Escondida and Chuquicamata. Administration Each province in the region is further subdivided into communes. Geography The main river is the Loa. Along the Coastal Cordillera lies Atacama Fault. The area of the Coastal Cordillera around the fault is rich in iron ore constituting the northern part of the so-called Chilean Iron Belt. These ore deposits are often of the manto-type deposits and are chiefly emplaced on rocks of La Negra Formation. Climate The average rainfall in the Antofagasta is just per year. From the coast, east to the Chilean Coast Range, is the south-central part of the Atacama Desert, the driest desert in the world. Further to the east, it is part of the less arid Central Andean dry puna ecoregion. The surroundings of abandoned Yungay town have been named the driest place in the world. Demography Most of the population lives on the coast in Antofagasta and Mejillones, or in Calama in the interior, the hub of the mining industry and the home of a large part of its work force. In the late 19th and early 20th centuries, immigrant settlers also arrived from Europe (mainly Croatians, Italians, Spaniards, Greeks, English, French, and Portuguese peoples), from the Levant, and in smaller numbers from China, Japan, Korea, Peru and Bolivia. Various immigration flows joined