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NATURALIST'S GUIDE TO THE AMERICAS 



The mountain-chains of this plateau 

 usually rise above timber-line and 

 occasionally, in the peak of Sumapaz 

 and the Sierra de Chita (or Cocuy), 

 receive snow. The axis of the Eastern 

 Cordillera, trending northeast as far 

 as Cocuy, turns thence abruptly north- 

 westward, forming the Pamplona high- 

 lands and reaching Ocafia at 8 N. A 

 low range of hills continues this axis 

 farther to the north, rising to moun- 

 tains in the Motillones and the Sierra 

 de Perija, and extending ultimately 

 nearly to the Goajira Peninsula, the 

 most northern point of Colombia. 

 From the Pamplona section of the 

 Eastern Cordillera a mountain-chain 

 diverges abruptly eastward, passing 

 soon into lower hills that form the gap 

 known as the Isthmus of Tachira but 

 then rising again so as to constitute the 

 eastward-trending Andes of Venezuela, 

 the snow-chain of the Sierra Nevada 

 de Merida. 



Beside the Andean cordilleras two 

 other mountain-systems must be men- 

 tioned. The Sierra Nevada de Santa 

 Marta, southeast of the city of that 

 name and within sight of the Caribbean 

 Sea, forms an irregular mountain-mass 

 rather extensively capped with snow. 

 The system is wholly isolated from the 

 Andes, although separated from the 

 Sierra de Perija only by a narrow lowland 

 plain. The Serrania de Baudo, skirting 

 the Pacific coast from the Choc6 Bay 

 at 4 N. northward, although chiefly a 

 range of low hills, is also to be carefully 

 distinguished from the Andes. The 

 Andean system terminates wholly in 

 the three cordilleras of Colombia, 

 whereas the Baudo chain is continuous 

 with the highlands of Panama and 

 forms part of a Central American land- 



B. River-systems and areas of lowland 



In western Colombia the areas of 

 lowland lie around and between the 

 mountain highlands while in eastern 

 Colombia the whole country consists 

 essentially of one vast plain, the north- 

 western part of the great interior low- 



land of South America. Proceeding 

 from the Pacific coast eastward the chief 

 river-systems and areas of lowland are 

 as follows. 



a. West of the Serrania de Baudo 

 occur only very short streams flowing 

 directly into the Pacific Ocean. 



6. Between the Serrania de Baudo 

 and the Western Cordillera is a valley 

 of some 50 mi. width, drained northward 

 into the Caribbean Sea by the Rio 

 Atrato and southward to the Pacific 

 Ocean by the Rio San Juan. South of 

 Choc6 Bay the numerous streams from 

 the Western Cordillera flow directly to 

 the Pacific, mostly across an extensive 

 lowland. The whole area from the Gulf 

 of Darien to Tumaco is known as the 

 Choc6. 



c. Between the Western Cordillera 

 and the Central Cordillera is the long 

 narrow Cauca Valley, drained north- 

 ward by the Rio Cauca. In El Cauca 

 near Popayan and especially in El 

 Valle the floor of the valley is a plain 

 reaching 20 to 25 miles in width 

 but elsewhere it is much cut into 

 hills and gorges. In Caldas and Anti- 

 oquia the Rio Cauca has cut its way by 

 gorges and deep canyons down from the 

 elevation of the Cauca Plain, 1000 

 meters, nearly to sea-level. South of 

 Popayan the Rio Patia drains the south- 

 ern extension of this inter-Andean 

 lowland, being the only stream of 

 Colombia to burst through the Western 

 Cordillera to reach the Pacific. 



d. Between the Central Cordillera 

 and the Eastern Cordillera is the Mag- 

 dalena Valley, broader and lower than 

 the Cauca Valley. It is drained by the 

 Rio Magdalena, a river which, flowing 

 northward to the Caribbean Sea, forms 

 Colombia's main artery of traffic. 

 Much of the valley floor is a plain, but 

 areas of hills occur in Tolima and Huila. 

 The most considerable plains are about 

 Neiva in Huila, Mariquita in Tolima, 

 and in eastern Antioquia. The Bogotd, 

 tableland is drained through the Rio 

 Sogomoso, Rio Carare, Rio Sumapaz 

 and other streams into the Magdalena. 



e. Fronting the Caribbean Sea a n( j 



