480 



Tarma and Huarocheri, we are inclined to 

 consider them as one immense basin 180 leagues 

 long, and crossed at the first third of its length, 

 by a dyke, or ridge 18,000 toises broad. In 

 fact, the two Alpine lakes of Lauricocha and 

 Chinchaycocha, which give birth to the river of 

 the Amazons and the Rio de Jauja, are placed 

 south and north of this rocky dyke, formed by 

 a prolongation of the knot of Huanuco and 

 Pasco. The Amazon, in issuing from the lon- 

 gitudinal valley, that bounds the chains of 

 Caxamarca and Chachacocha, breaks, as we 

 have already said in another place *, the latter 

 of those chains, which merits the name of cen- 

 tral without being the most lofty ; the point 

 where the great river penetrates into the moun- 

 tains is very remarkable. Entering the Ama- 

 zon by the Rio Chamaya or Guancabamba, I 

 found opposite the confluence, the picturesque 

 mountain of Patachuana; but the rocks on 

 both banks of the Amazon begin only between 

 Tambillo and Tomependa (lat. 5° 31', long. 

 80° 56'). From thence to Pongo de Rentema, 

 a long succession of rocks follow, of which the 

 last is the Pongo de Tayouchouc, between the 

 strait of Manseriche and the village of San 

 Borja. The course of the Amazon, at first di- 

 rected north, and then east, changes near Pu- 



* Vol. v, p, 41. 



