OEAOUAL SINKING OF THE CHAINS. 315 
(lat. 8° 330 = if conical, between tbe 
mouth of the Eio 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 TJraba or Darien, between the Eio 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 foiuth 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 Cupiea 
and the embarcadero of the Eio 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 Eio Tuyra and Chucunaque or Chueiinque, 
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 toises. The 
interior of Darfur is not more unknown to geographers 
than the humid, insalubrious forest-land whicli 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 Cupiea 
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 Pauama, by their direction and their geographical 
position, may be considered as a continuation ol the moun- 
tains of Antioquia and Choco; but on the west of Bas- 
Atrato, there is scarcely a ridge in the plain. W e do not 
find in this country a group of interposed mountains like 
that which links (between Barquesimeto, Nirgua, and \ a- 
lencia) the eastern chain of New Grenada (that of Suma 
Paz and the Sierra Nevada de Merida) to the Cordillera ot 
the shore of Venezuela. 
The Cordillera of the Andes, considered m its whole 
extent, from the rocky wall of the island of Diego Kamirez, 
to the isthmus of Panama, is sometimes ramified into chains 
more or less parallel, and sometimes articulated by immense 
