Biology Reference
In-Depth Information
Figure 2.41
Northern Andes of Colombia and western Venezuela showing, left to right, ac-
creted oceanic terranes of the Pacifi c Coast, Cordillera Occidental, Cauco Valley, Cordillera
Central, Magdalena Valley, and Cordillera Oriental dividing northward into the Sierra de
Perija and Mérida Andes surrounding the Maracaibo Basin. From Orme 2007a. Used with
permission from Oxford University Press, Oxford.
mammals from the Cangahua Formation that records the disappearance of
mastodonts from Ecuador, along with later fl uctuations in the abundance of
mylodonts (ground sloths) and equids (hooved animals, horses and related
genera) with the cold, dry climates of the approaching LGM (21-18 kyr). As
late as the early Miocene (23 Ma), the mountains were still relatively low,
and there were passages through them because the Pacifi c Ocean extended
eastward to the Oriente Province of Ecuador, and both the proto-Orinoco
River and the proto-Amazon River were draining westward into the Pacifi c
Ocean.
In southern Colombia, the Northern Andes branch to form the Cordil-
lera Occidental, Central, and Oriental (fi g. 2.41). The Cordillera Oriental
further branch into the western Sierra Nevada de Santa Marta / Sierra de
Perija and the eastern Cordillera Mérida of northern Colombia and Ven-
ezuela, enclosing Lake Maracaibo, nearly fi lled with 7000 m of sediment
(fi g. 2.35). There are several features of the region important to the his-
tory and economic development of South America. The city of Cumaná
was established on the northeast coast of Venezuela by Dominican friars
in 1513, almost a hundred years before Jamestown, Virginia, and it is the
