Biology Reference
In-Depth Information
oldest Spanish settlement in South America. The Maracaibo Basin is an
inlet between the Sierra Nevada de Santa Marta and the Cordillera de
Mérida, and it contains large petroleum reserves. The discovery of oil in
the New World by Europeans dates from the 1589 explorations by the Span-
iard Juan de Castellanos on Cubagua off the coast of Venezuela. However,
three decades earlier, Humboldt had noted a strong smell of petroleum
near Cape de La Brea where the petroleum covers the surface of the sea
a thousand feet from the coast ([1852] 1971). Studies by Jan Muller of the
Dutch Shell Oil Company, and by Estella de Di Giacomo, Maria Lorente,
and others of the Petróleos de Venezuela, have provided valuable informa-
tion on the Tertiary vegetation and environments of the region, and the
plant microfossil record is known in considerable detail because of its use
in the petroleum industry for correlation, zonation, and paleodeposition
reconstructions.
Within the mountain highlands, basins have accumulated fossil spore
and pollen-bearing sediments thousands of feet thick dating back to the late
Pliocene (4-3 Ma). The early studies of Thomas van der Hammen, and
current investigations by Henry Hooghiemstra, Antoine Cleef, and their
colleagues have made this one of the paleobotanical “hot spots” in Latin
America.
In the Late Cretaceous, the volcanic Cordillera Occidental was accreted
onto northwestern South America, as indicated by a line of ophiolites along
the Romeral fault zone. It began its principal rise in the Oligocene and early
Miocene. Such knowledge of volcanoes, vegetation, and other features can
easily be imparted, but this belies the hazards involved in getting the infor-
mation. In November 1985, Nevado del Ruiz (5300 m) in southern Colom-
bia suddenly erupted, causing the death of 23,000 people; and on 14 January
1993, nine geologists were killed in another explosive eruption of Galeras
in the same region. Slightly different accounts of the Galeras disaster are
given by Victoria Bruce in
No Apparent Danger
(2001) and by Stanley Wil-
liams and Fen Montaigne in
Surviving Galeras
(2001).
The volcanic Cordillera Central and the essentially nonvolcanic Oriental
were uplifted by subduction of the Nazca plate in the Miocene and reached
their present heights at around 6-3 Ma. Uplift is estimated at an annual
rate of 3 mm during the Pliocene. Other parts of northwestern South Amer-
ica were added on at about the same time through movement of the Carib-
bean plate. These include the Guajira Peninsula, the Sierra Nevada de Santa
Marta block, and the offshore Caribbean Mountain system. The peaks of
the Caribbean Mountains constitute the present-day Netherlands Antilles,
or the ABC islands of Aruba, Bonaire, and Curaçao, which emerged in the
