GEOLOGY OF PERU ADAMS. 393 



not differ materially from that by Humboldt. Kaimondi gives a 

 description of the Cordillera Occidental and notes a list of 42 of its 

 passes, which vary from 2,186 meters to 5,075 meters. From Huama- 

 chiico in latitude 7° 45' southward the 27 passes are more than 4,000 

 meters above the sea. The lowest pass is that of Huarmaca, in the 

 department of Piura, which is 2,180 meters. 



His further description of this Cordillera as to structure, age, 

 and snow line, etc., will be given under other heads in this paper. 

 Here, however, it will be noted that he says the southern part of the 

 Cordillera Occidental is not a single range, but rather a broad ele- 

 vated band or high plateau, on which are situated volcanic peaks. It 

 may perhaps be added here with propriety that the Continental 

 Divide is a continuous range and that the volcanic peaks do not fol- 

 low the Cordillera, but are found in an irregular double line crossing 

 the western part of the high plateau. The relation of this line of 

 peaks to the change in direction of the Cordillera is not unlike that 

 of a string to a bow. 



It will be remembered that Humboldt spoke of a mountainous area 

 to the east in the forest region. Raimondi did not touch on this 

 point, and indeed it is not yet possible to tell just what is the disposi- 

 tion of the mountains of this region, for although many explorations 

 have been made the wooded country has prevented the mapping of 

 the topographic features. The Cordillera Central, according to 

 Humboldt, joins the Occidental in the knot of Loja, in Ecuador. 

 Perhaps Raimondi did not ttouch on this point in his description 

 because Loja is outside of Peru, and consequently beyond the limit 

 of his explorations. He seems to have accepted the statements of 

 Humboldt in his mapping. 



Wolf, however (1892), in his description of the Andes, says that 

 he does not agree with the opinion that the Cordillera Oriental unites 

 in the knot of Loja, as is shown on the map of Ecuador by Santiago 

 y Morona and of Peru by Raimondi. He states that the Cordillera 

 cut by the Pongo de Manseriche (Falls of Manseriche) is the last 

 branch of the Peruvian mountains which reaches the Amazon. It 

 appears not to be very high, since explorers speak of 600 meters at 

 the locality of the falls, and he thinks that to the north it lowers and 

 is lost in the plains between the rivers Santiago and Morona. 



Wolf also says that to the east of Ecuador from where the rivers 

 are navigable the country is a great plain, with only small areas of 

 gradual undulations, and that the high mountains of the old maps, as 

 also those of Raimondi, are imaginary and do not exist. 



The accompanying sketch map (pi. 1) shows the disposition of the 

 Cordilleras according to the foregoing description. The Ecuadoran 

 portion is from the sketch published by Wolf, 



