424 



Alpine lake of Titicaca change their direction 

 abruptly, and incline towards the north-west. 

 The Cordilleras of Ancuma and Moquehua, and 

 the longitudinal valley, or rather the basin of 

 Titicaca, which they inclose, are directed N. 

 42° W. Further on, the two branches again 

 unite in the knot of the mountains o/Cuzco, and 

 thence their direction is N. 80° W. This knot, 

 of which the table -land inclines to the north- 

 east, presents a real curve, nearly directed from 

 east to west, so that the part of the Andes north 

 of Castrovireyna is thrown back more than 

 242,000 toises towards the west. So singular 

 a geological phenomenon reminds us of the 

 variation d? allure of the veins, and especially of 

 the two parts of the chain of the Pyrenees, pa- 

 rallel to each other, and linked by an almost 

 rectangular elbow, 16,000 toises long, near the 

 source of the Garonne * ; but in the Andes, the 

 axes of the chain, south and north of the curve, 

 do not preserve a parallelism. On the north of 

 Castrovireyna and Andahuaylas (lat. 14°), the 

 direction is N. 22° W., while south of 15°, it is 

 N. 42° W. The inflexions of the coast follow 

 these changes ; the shore separated from the 

 Cordillera by a plain 15 leagues broad, stretches 

 like the Cordillera at Arica, between 271° and 



* Between the mountain of Tentenacle and the Port 

 d'Espot (Charpentier, p. 10). 



