GRADUAL SINKING OF THE CHAINS. 815 



(lat. 8 33*) : at least if the hills, often conical, between the 

 mouth of the liio Sinu and the small town of Tolu, or even 

 the calcareous heights of Turbaco and Popa, near Cartha- 

 gena, may not be regarded as the most northern prolongation 

 of this second branch. A third advances towards the gulf 

 of Uraba or Darien, between the Rio San Jorge and the 

 Atrato. It is linked southward with the Alto del Viento, 

 or Sierra de Abide, and is rapidly lost, advancing as far 

 as the parallel of 8. Finally, the fourth branch of the 

 Andes of Antioquia, situated westward of Zitara and the 

 Eio Atrato, undergoes, long before it enters the isthmus of 

 Panama, such a depression, that between the Gulf of Cupica 

 and the embarcadero of the Bio Naipipi, we find only a plain 

 across which M. Gogueneche has projected a canal for the 

 junction of the two seas. It would be interesting to know 

 the configuration of the strata between Cape Garachine, or 

 the Gulf of St. Miguel, and Cape Tiburon, especially towards 

 the source of the Kio Tuyra and Chucunaque or Chucunque, 

 so as to determine with precision where the mountains of 

 the isthmus of Panama begin to rise ; mountains whose ele- 

 vation does not appear to be more than 100 toisea. The 

 interior of Darfur is not more unknown to geographers 

 than the humid, insalubrious forest-land which extends on 

 the north-west of Betoi and the confluence of the Bevara 

 with the Atrato, towards the isthmus of Panama. All that 

 we positively know of it hitherto is, that between Cupica 

 and the left bank of the Atrato, there is either a land-strait, 

 or a total absence of the Cordillera. The mountains of the 

 isthmus of Panama, by their direction and their geographical 

 position, may be considered as a continuation of the moun- 

 tains of Antioquia and Choco ; but on the west of Bas- 

 Atrato, there is scarcely a ridge in the plain. We do not 

 find in this country a group of interposed mountains like 

 that which links (between Barquesimeto, Nirgua, and Va- 

 lencia) the eastern chain of New Grenada (that of Suma 

 Paz and the Sierra Nevada de Merida) to the Cordillera of 

 the shore of Venezuela. 



The Cordillera of the Andes, considered in its whole 

 extent, from the rocky wall of the island of Diego Ramirez, 

 to the isthmus of Panama, is sometimes ramified into chains 

 more or less parallel, and sometimes articulated by immense 



