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 it is known as the Cordillera Silillica, and then following the trend of the coast north-westward into Peru becomes the Cordillera Occidental. The western slopes of the Andes are precipitous, with short spurs enclosing deep valleys. The whole system is volcanic, and a considerable number of volcanoes are still intermittently active, noticeably in central and southern Chile. The culminating point of the Chilean Andes is Aconcagua, which rises to a height of 23,097 ft.

In southern Chile the coast is highly mountainous, but the relation of these elevations to the Andes has not been clearly determined. The highest of these apparently detached groups are Mt. Macá (lat. 45° S.), 9711 ft., and Mt. Arenales (about 47° S. lat.), 11,286 ft. Cathedral Peak on Wellington Island rises to a height of 3838 ft. and the highest point on Taytao peninsula to 3937 ft. The coast range of central Chile has no noteworthy elevations, the culminating point in the province of Santiago being 7316 ft. Between central Chile and the northern desert region there is a highly mountainous district where distinct ranges or elongated spurs cross the republic from the Andes to the coast, forming transverse valleys of great beauty and fertility. The most famous of these is the “Vale of Quillota” between Valparaiso and Santiago. The Chilean Andes between Tacna and Valdivia are crossed by 24 passes, the majority of them at elevations exceeding 10,000 ft. The best-known of these is the Uspallata pass between Santiago and the Argentine city of Mendoza, 12,870 ft. above sea-level. The passes of central and southern Chile are used only in the summer season, but those of northern Chile are open throughout the whole year.

The volcanic origin of the Andes and their comparatively recent elevation still subject Chile, in common with other parts of the western coast region, to frequent volcanic and seismic disturbances. In some instances since European occupation, violent earthquake shocks have resulted in considerable elevations of certain parts of the coast. After the great earthquake of 1835 Captain Robert FitzRoy (1805–1865) of H.M.S. “Beagle” found putrid mussel-shells still adhering to the rocks 10 ft. above high water on the island of Santa Maria, 30 m. from Concepción, and Charles Darwin declares, in describing that disaster, that “there can be no doubt that the land round the bay of Concepción was upraised two or three feet.” These upheavals, however, are not always permanent, the upraised land sometimes settling back to its former position. This happened on the island of Santa Maria after 1835. The existence of sea-shells at elevations of 350 to 1300 ft. in other parts of the republic shows that these forces, supplemented by a gradual uplifting of the coast, have been in operation through long periods of time and that the greater part of central and southern Chile has been raised from the sea in this way. These earthquake shocks have two distinct characteristics, a slight vibration, sometimes almost imperceptible, called a temblor, generally occurring at frequent intervals, and a violent horizontal or rotary vibration, or motion, also repeated at frequent intervals, called a terremoto, which is caused by a fracture or displacement of the earth’s strata at some particular point, and often results in considerable damage. When the earthquake occurs on the coast, or beneath the sea in its vicinity, tidal waves are sometimes formed, which cause even greater damage than the earthquake itself. Arica has been three times destroyed by tidal waves, and other small towns of the north Chilean coast have suffered similar disasters. Coquimbo was swept by a tidal wave in 1849, and Concepción and Talcahuano were similarly destroyed in 1835. The great earthquake which partially destroyed Valparaiso in 1906, however, was not followed by a tidal wave. These violent shocks are usually limited to comparatively small districts, though the vibrations may be felt at long distances from the centre of disturbance. In this respect Chile may be divided into at least four great earthquake areas, two in the desert region, the third enclosing Valparaiso, and the fourth extending from Concepción to Chiloé. A study of Chilean earthquake phenomena, however, would probably lead to a division of southern Chile into two or more distinct earthquake areas.

The coast of Chile is fringed with an extraordinary number of islands extending from Chiloé S. to Cape Horn, the grouping of which shows that they are in part the summits of a submerged mountain chain, a continuation southward of the Cordillera Maritima. Three groups of these islands, called the Chiloé, Guaytecas and Chonos archipelagoes, lie N. of the Taytao peninsula (lat. 45° 50′ to 46° 55′ S.), and with the mainland to the E. form the province of Chiloé. The largest of these is the island of Chiloé, which is inhabited. Some of the smaller islands of these groups are also inhabited, though the excessive rainfall of these latitudes and the violent westerly storms render them highly unfavourable for human occupation. Some of the smallest islands are barren rocks, but the majority of them are covered with forests. These archipelagoes are separated from the mainland in the north by the gulfs of Chacao (or Ancud) and Corcovado, 30 to 35 m. wide, which appear to be a submerged part of the great central valley of Chile, and farther south by the narrower Moraleda channel, which terminates southward in a confusing network of passages between the mainland and the islands of the Chonos group. One of the narrow parts of the Chilean mainland is to be found opposite the upper islands of this group, where the accidental juxtaposition of Magdalena island, which indents the continent over half a degree at this point, and the basin of Lake Fontana, which gives the Argentine boundary a sharp wedge-shaped projection westward, narrows the distance between the two to about 26 m. The Taytao peninsula, incorrectly called the Tres Montes on some maps, is a westward projection of the mainland, with which it is connected by the narrow isthmus of Ofqui, over which the natives and early missionaries were accustomed to carry their boats between the Moraleda Channel and Gulf of Peñas. A short ship canal here would give an uninterrupted and protected inside passage from Chacao Channel all the way to the Straits of Magellan, a distance of over 760 m. A southern incurving projection of the outer shore-line of this peninsula is known as Tres Montes peninsula, the most southern point of which is a cape of the same name. Below the Taytao peninsula is the broad open Gulf of Peñas, which carries the coast-line eastward fully 100 m. and is noticeably free from islands. The northern entrance to Messier Channel is through this gulf. Messier, Pitt, Sarmiento and Smyth’s Channels, which form a comparatively safe and remarkably picturesque inside route for small steamers, about 338 m. in length, separate another series of archipelagoes from the mainland. These channels are in places narrow and tortuous. Among the islands which thickly fringe this part of the coast, the largest are Azopardo (lying within Baker Inlet), Prince Henry, Campaña, Little Wellington, Great Wellington and Mornington (of the Wellington archipelago), Madre de Dios, Duke of York, Chatham, Hanover, Cambridge, Contreras, Rennell and the Queen Adelaide group of small barren rocks and islands lying immediately north of the Pacific entrance to the Straits of Magellan. The large number of English names on this coast is due to the fact that the earliest detailed survey of this region was made by English naval officers; the charts prepared from their surveys are still in use and form the basis of all subsequent maps. None of these islands is inhabited, although some of them are of large size, the largest (Great Wellington) being about 100 m. long. It has likewise been determined, since the boundary dispute with Argentina called attention to these territories and led to their careful exploration at the points in dispute, that Skyring Water, in lat. 53° S., opens westward into the Gulf of Xaultegua, which transforms Ponsonby Land and Cordoba (or Croker) peninsula into an island, to which the name of Riesco has been given. The existence of such a channel was considered probable when these inland waters were first explored in 1829 by Captain FitzRoy, but it was not discovered and surveyed until three-quarters of a century had elapsed. Belonging to the Fuegian group south of the Straits of Magellan are Desolation, Santa Ines, Clarence, Dawson, Londonderry, Hoste, Navarin and Wollaston islands, with innumerable smaller islands and rocks fringing their shores and filling the channels between them. Admirable descriptions of this inhospitable region, the farthest south of the inhabited parts of the globe, may be found in the Narrative of the Surveying Voyages of His Majesty’s Ships “Adventure” and “Beagle” between the years 1826 and 1836 (3 vols., 1839).

The western and larger part of (q.v.) belongs to Chile. About 63 m. S.W. of Cape Horn, in lat. 56° 25′ S., is the Diego Ramirez group of small, rocky islands, the most southern possession of the republic. Its westernmost possessions are Sala-y-Gomez and Easter islands, the former in about 27° S., 105° W., and the latter, the easternmost inhabited Polynesian island, in 27° 6′ S., 109° 17′ W. Much nearer the Chilean coast (396 m.), lying between the 33rd and 34th parallels, are the three islands of the Juan Fernandez group, and rising apparently from the same submerged plateau about 500 m. farther north of the latter are the rocky islets of San Ambrosio and San Felix, all belonging to Chile. North of Chiloé there are few islands in close proximity to the coast. The more important of these are La Mocha, off the southern coast of Arauco, in lat. 38° 20′ S., which is 8 m. long and rises to an elevation of 1240 ft. above the sea; Santa Maria, 30 m. south-west of Concepcion, which partially encloses the Bay of Arauco and is well cultivated; and Quiriquina, lying off the port of Talcahuano in the entrance to Concepción bay. There are a few barren islands on the desert coast, the largest of which are between Coquimbo and Caldera. Since the removal of their guano deposits they have become practically worthless, except where they serve to shelter anchorages.

The coast of northern and central Chile is singularly deficient in good harbours. Those of the desert region are only slight indentations in a remarkably uniform coast-line, sheltered on one side by a point of land, or small island. The landings are generally dangerous because of the surf, and the anchorages are unsafe from storms on the unprotected side. Among the most frequented of these are Valparaiso, Coquimbo, Caldera, Iquique and Arica. There are some small harbours for coasting vessels of light draught along the coast of central Chile, usually at the partially obstructed mouths of the larger rivers, as San Antonio near the mouth of the Maipó, Constitución at the mouth of the Maule, and Llico on the outlet of Lake Vichuquen, but there is no harbour of importance until Conceptión (or Talcahuano) Bay is reached. There are three harbours on this bay,, and  (q.v.), the last being the largest and best-protected port on the inhabited part of the Chilean coast. Immediately south of this bay is the large Bay of Arauco, into which the Bio-Bio river discharges, and on which, sheltered by the island of Santa Maria, are the ports of Coronel and Lota. The next important harbour is that of El Corral, at the mouth of the Valdivia river and 15 m. below