Narrative of the surveying voyages of his majesty's ships Adventure and Beagle (vol.1): between the years 1826 and 1836 : describing their examination of the southern shores of South America, and the Beagles's circumnavigation of the globe

566 HEIGHTS WESTERN COAST. Strait of Magalhaens the average height may be taken at three thousand feet ; though there are some mountains which may be between six and seven thousand feet high. By a reference to the chart it will be seen that about the parallel of 40° the coast begins to assume^ and retains to its furthest extre- mity, a very different appearance from that which it exhibits to the northward, where the sea, which is kept at a distance from the Cordillera by a belt of comparatively low land for continuous intervals of some hundred miles, washes a long unbroken shore, affording neither shelter for vessels nor landing for boats ; but; to the southward of that parallel, its waters reach to the very base of the great chain of the Andes, and, flowing as it were into the deep ravines that wind through its ramifications, form numerous channels, sounds, and gulfs, and, in many instances, insulate large portions of land. In fact, the whole of this space is fronted by large islands and exten- sive archipelagoes, of which the most conspicuous are the great island of Childe, Wellington Island, the Archipelago of Madre de Dios, Hanover Island, and Queen Adelaide Archipelago. The last forms the western entrance of the Strait on its north side. The land of Tres Montes, however, is an exception : it is a penin- sula, and is the only part of the continent within the above limits that is exposed to the ocean's swell. It forms the northern part of the Gulf of Pefias, and is joined to the main by the nari'ow isthmus of Ofqui, over which the Indians, in travelling along the coast, carry their canoes, to avoid the extreme danger of passing round the peninsula. It was here that Byron and his shipwrecked com- panions crossed over with their Indian guides : but it is a route that is not much frequented ; for this part of the coast is very thinly inhabited, and the trouble of pulling to pieces and recon- structing the canoes,* an operation absolutely necessary to be performed, is so great, that I imagine it is only done on occa- sions of importance. In this way the piraguas which conveyed the missionary voyagers to the Guaianeco Islands were transported • During our examination of this pai"t, our boats ascended the river San Tadeo, and endeavoured in vain to find any traces of the road ; an ahnost impenetrable jungle of reeds and underwood lined the banks of the river, and time was too valuable to admit of further delay, in search of an object comparatively of minor importance.