GEOLOGY OF PERU—ADAMS. 393 
not differ materially from that by Humboldt. Raimondi 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- 
chuco 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. 
Tt 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 (pl. 1) shows the disposition of the 
Cordilleras according to the foregoing description. The Ecuadoran 
portion is from the sketch published by Wolf. 
