The following discussion on the climate of the southern parts of the continent with relation to its productions, on the snow-line, on the extraordinarily low descent of the glaciers, and on the zone of perpetual congelation in the antarctic islands, may be passed over by any one not interested in these curious subjects, or the final recapitulation alone may be read. I shall, however, here give only an abstract, and must refer for details to the Thirteenth Chapter and the Appendix of the former edition of this work.
On the Climate and Productions of Tierra del Fuego and of the South-west Coast. -- The following table gives the mean temperature of Tierra del Fuego, the Falkland Islands, and, for comparison, that of Dublin: --
Summer Winter Mean of Summer
Latitude Temp. Temp. and Winter
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Tierra del Fuego 53 38' S. 50 33.08 41.54
Falkland Islands 51 38' S. 51 -- --
Dublin 53 21' N. 59.54 39.2 49.37
Hence we see that the central part of Tierra del Fuego is colder in winter, and no less than 9.5 degs. less hot in summer, than Dublin. According to von Buch, the mean temperature of July (not the hottest month in the year) at Saltenfiord in Norway, is as high as 57.8 degs., and this place is actually 13 degs. nearer the pole than Port Famine! [8] Inhospitable as this climate appears to our feelings evergreen trees flourish luxuriantly under it. Humming-birds may be seen sucking the flowers, and parrots feeding on the seeds of the Winter's Bark, in lat. 55 degs. S. I have already remarked to what a degree the sea swarms with living creatures; and the shells (such as the Patellae, Fissurellae, Chitons, and Barnacles), according to Mr. G. B. Sowerby, are of a much larger size and of a more vigorous growth, than the analogous species in the northern hemisphere. A large Voluta is abundant in southern Tierra del Fuego and the Falkland Islands. At Bahia Blanca, in lat. 39 degs. S., the most abundant shells were three species of Oliva (one of large size), one or two Volutas, and a Terebra. Now, these are amongst the best characterized tropical forms. It is doubtful whether even one small species of Oliva exists on the southern shores of Europe, and there are no species of the two other genera. If a geologist were to find in lat 39 degs. on the coast of Portugal a bed containing numerous shells belonging to three species of Oliva, to a Voluta and Terebra, he would probably assert that the climate at the period of their existence must have been tropical; but judging from South America, such an inference might be erroneous.
The equable, humid, and windy climate of Tierra del Fuego extends, with only a small increase of heat, for many degrees along the west coast of the continent. The forests for 600 miles northward of Cape Horn, have a very similar aspect. As a proof of the equable climate, even for 300 or 400 miles still further northward, I may mention that in Chiloe (corresponding in latitude with the northern parts of Spain) the peach seldom produces fruit, whilst strawberries and apples thrive to perfection. Even the crops of barley and wheat [9] are often brought into the houses to be dried and ripened. At Valdivia (in the same latitude of 40 degs., with Madrid) grapes and figs ripen, but are not common; olives seldom ripen even partially, and oranges not at all. These fruits, in corresponding latitudes in Europe, are well known to succeed to perfection; and even in this continent, at the Rio Negro, under nearly the same parallel with Valdivia, sweet potatoes (convolvulus) are cultivated; and grapes, figs, olives, oranges, water and musk melons, produce abundant fruit. Although the humid and equable climate of Chiloe, and of the coast northward and southward of it, is so unfavourable to our fruits, yet the native forests, from lat. 45 to 38 degs., almost rival in luxuriance those of the glowing intertropical regions. Stately trees of many kinds, with smooth and highly coloured barks, are loaded by parasitical monocotyledonous plants; large and elegant ferns are numerous, and arborescent grasses entwine the trees into one entangled mass to the height of thirty or forty feet above the ground. Palm-trees grow in lat 37 degs.; an arborescent grass, very like a bamboo, in 40 degs.; and another closely allied kind, of great length, but not erect, flourishes even as far south as 45 degs. S.
An equable climate, evidently due to the large area of sea compared with the land, seems to extend over the greater part of the southern hemisphere; and, as a consequence, the vegetation partakes of a semi-tropical character. Tree-ferns thrive luxuriantly in Van Diemen's Land (lat. 45 degs.), and I measured one trunk no less than six feet in circumference. An arborescent fern was found by Forster in New Zealand in 46 degs., where orchideous plants are parasitical on the trees. In the Auckland Islands, ferns, according to Dr. Dieffenbach [10] have trunks so thick and high that they may be almost called tree-ferns; and in these islands, and even as far south as lat. 55 degs. in the Macquarrie Islands, parrots abound.