Biology Reference
In-Depth Information
When Magellan and his crew exited from the strait in 1520, they sailed for
three months and twenty days in calm waters, for which they named the
ocean “Pacifi c.” In 1830, when Captain James FitzRoy visited the island
with Charles Darwin aboard as naturalist, he took back to England four
natives they named Jemmy Button, York Minster, Fuegia Basket, and Boat
Memory (who died in England). The Tierra de Fuegans were dressed in
proper British attire, presented to the royal court, and educated with the
intention of returning them to the island to spread Christianity. It was a
bizarre experiment, as insensitive as it was a failure, and the natives quickly
returned to their familiar ways. To the south of Tierra del Fuego in the
Beagle Channel are the several islands that constitute Cape Horn. Named
by the Dutch for their home port of Hoorn, it is the southern terminus of
the South American continent.
The vegetation is mostly bog and moorland, with scattered forests of
Arau caria
(Ruiz et al. 2007) and
Nothofagus
(southern beech; McEwan et al.
1997; Veblen 2007). Grasslands and dry shrublands or steppe are character-
istic of the Río de la Plata plains and Patagonia. Rainfall is 2600 mm a year
along the Pacifi c coast, 4000 mm on the western mainland, 10,000 mm on
the upper slopes of the Southern Andes, and 430 mm in the frigid south and
east at Punta Arenas on the Strait of Magellan. MAT ranges from about 14°C
in the south to 19°C in the north, and temperatures are relatively mild in
most of the lowlands and at midelevations because of the maritime climate.
The climate and vegetation regime of this far southern and fragmented land-
scape is delicately balanced, however, and slight changes in climate-forcing
mechanisms produce signifi cant alterations in the grassland-steppe-forested
communities. Glaciation was already underway by the Pliocene (3.5 Ma),
and spores and pollen from the bogs have been a source of considerable
information on Quaternary vegetation and environmental history through
studies by Calvin Heusser, M. E. Quattrocchio, M. L. Salgado-Labouriau,
and others (chap. 8).
The Central Andes
As the Atlantic Ocean continued to open northward and subduction of the
Pacifi c plate intensifi ed, uplift of the Central Andes accelerated. They ex-
tend from the Golfo de Penas at 46°S in southern Chile to near a major
megashear zone called the Amotape Cross at 5°S in southern Ecuador at
the Golfo de Guayaquil. This is the longest, highest, widest, and most com-
plex segment of the Andean cordillera. There are large deposits of copper,
gold, iron, lead, silver, tin, and zinc in Chile, Bolivia, and Peru, and, partly
