Cordillera on the northern slopes of the Alto del Viento, in about
lat. 7 deg. N., and not far from the sources of the Sinu and Bacuba, is
essentially a river of the plain, flowing north-east across a level
country filled with small lakes and subject to inundations to a
junction with the Cauca just before it joins the Magdalena. Both the
San Jorge and Nechi are navigable for considerable distances. The
valley of the Cauca is much narrower than that of the Magdalena, and
between Cartago and Caceres the mountain ranges on both sides press
down upon the river and confine it to a narrow canyon. The Cauca
unites with the Magdalena about 200 m. from the sea through several
widely separated channels, which are continually changing through the
wearing away of the alluvial banks. These changes in the channel are
also at work in the Lower Magdalena. The remaining rivers of the
Caribbean system, exclusive of the smaller ones rising in the Sierra
Nevada de Santa Marta, are the Zulia and Catatumbo, which rise in the
mountains of northern Santander and flow across the low plains of the
Venezuelan state of Zulia into Lake Maracaibo.

Of the rivers of the great eastern plains, whose waters pass through
the Orinoco and Amazon to the Atlantic, little can be said beyond the
barest geographical description. The size and courses of many of their
affluents are still unknown, as this great region has been only
partially explored. The largest of these rivers flow across the plains
in an easterly direction, those of the Orinoco system inclining
northward, and those of the Amazon system southward. The first include
the Guaviare or Guayabero, the Vichada, the Meta, and the upper course
of the Arauca. The Guaviare was explored by Crevaux in 1881. It rises
on the eastern slopes of the Eastern Cordillera between the 3rd and
4th parallels, about 75 m. south of Bogota, and flows with a slight
southward curve across the llanos to the Orinoco, into which it
discharges at San Fernando de Atabapo in lat. 4 deg. N. Its largest
tributary is the Inirida, which enters from the south. The Guaviare
has about 600 m. of navigable channel. The Meta rises on the opposite
side of the Cordillera from Bogota, and flows with a sluggish current
east-north-east across the llanos to the Orinoco, into which it
discharges below the Atures rapids, in lat. 6 deg. 22' N. It is navigable
throughout almost it