THE PERUVIAN CORDILLEEAS. 281 



flowing from one to another. Then the sills between each basin were slowlv 

 eroded by the stream till all the intervening rising grounds were levelled. 

 Nevertheless, the observer may still recognise the several terraces of the old 

 lakes, now transformed to verdant basins. 



The Central Cordilleras. 



South of the source of the Maranon all the converging chains, connected by 

 lofty intermediate ridges, form the knot or group of the Cerro de Pasco, so named 

 from the neighbouring city. Nevertheless, the two main ranges, Andes and 

 Cordillera, may still be clearly distinguished in this section of the orographic 

 sj'^stem. Huaylillas, one of the summits of the group, towers to a height of 16,240 

 feet. Farther on, the range of the Andes proper, consisting of mesozoic rocks 

 with crystalline nodes cropping out, trends away with perfectly clear outline in 

 the direction of the south-east, with peaks over 13,000 feet high, but carved into 

 separate blocks by the Perene and Mantaro affluents of the Ucayali. North-west 

 of Cuzco it is even completely obliterated by the erosive action of the numerous 

 main headwaters of the Apurimac, radiating like the ribs of a fan through a vast 

 basin at a mean altitude of 7,600 feet. 



A chain rising east of the Apurimac is followed by a second east of the Pau- 

 cartambo, both evidently belonging to the same system, and developing their main 

 axis in the same direction from north-west to south-east. One of the summits of 

 the Sierra de Yilcaconga, east of the Apurimac valley, rises to a height of 13,650 

 feet, but it is greatly exceeded by the Carabaya range dominating the vast region 

 of the Montana, source of the great Amazonian rivers. Several of the snowy 

 peaks of this range certainly rise above lô,500 feet. Chololo, which, however, 

 lies in Bolivian territory a little beyond the Peruvian frontier, would appear to 

 be 17,625 feet high. 



This mountain indicates a break in the general trend of the system, which is 

 here deflected a little to the south, as if in anticipation of the movement which 

 farther on gives to the whole of the Andes, together with the continental sea- 

 board itself, a normal direction from north to south in a line with the meridian. 



East of the Piios Huallaga and Ucayali the ranges of heights, mountains or 

 hills not yet measured are all developed parallel with the two main rano-es of 

 the Cordilleras and Andes. 



South of the Pasco knot the Cordillera, properly so called, becomes merged 

 in the escarpments of the inter- Andean uplands, rising but little above the level 

 of the inland plateau. It takes the name of Ceja (" Eyebrow ") of the Sierra, 

 and presents the aspect of a mountain chain only on its west side, facino- the 

 Pacific. Nevertheless, it has some very lofty peaks, such as 7iuda, north-east of 

 Lima, and Meiggs, named from the engineer who pierced the crest of the Cordillera 

 by a railway tunnel, both about 15,270 feet high. Meiggs terminates in the 

 Pietra Parada, an isolated block on which the Archbishop of Lima was wont, 

 during his visitations, to celebrate Mass in the midst of the snows. 



