MOUNTAINS OF ECUADOR 223 



II. 



Physical Features — The Ecuadorean Andes. 



Viewed as a whole, the Ecuadorean Andes, stretching from the Pasto to the 

 Loja group, present a distinctive character in their relief, which has been 

 compared to a ladder of primitive construction with rude and twisted rungs, 

 varying in thickness, and following at irregular intervals. Eastwards runs the 

 main range, the " Royal Cordillera," as it is called, whose waters all descend to 

 the Amazons. Although Chimborazo, the culminating point of Ecuador, lies in 

 the western range, this eastern chain has a greater mean altitude (about 13,000 

 feet), while its crystalline rocks give it the first place in point of geological age. 

 It consists, partly in its northern, and altogether in its southern, section, of 

 granites, gneiss, and slaty schists, rocks which in the Western Cordillera nowhere 

 crop out except in the deepest valleys. Here the prevailing formations are 

 mesozoic strata, probably cretaceous, dominated by diorites, porphyries, and other 

 rocks of igneous origin. 



Despite its generally more regular trend, the eastern system presents a double 

 curvature, the first concave, the second convex, towards the plains at its foot. 

 The parallel western range follows an analogous direction, but with far more 

 numerous local irregularities and breaks in its normal disposition. So frequent, 

 in fact, are these breaks that Why m per went so far as to deny the existence of 

 the range as such, regarding the western edge of the main (eastern) chain 

 merely as "a certain sequence of peaks more or less in a line with each other." * 

 But whatever name be applied to this line of domes and crests, it remains none 

 the less a rim parallel to the greater Cordillera, and it is certainly regarded by 

 the inhabitants as a distinct range, broken into fragments by numerous river- 

 valleys. The Royal Cordillera is pierced through and through only by the two 

 rivers Pastaza and Paute, whereas the western chain is interrupted by no less 

 than seven watercourses having their sources in the upland basins of the interior. 

 The Mira, the Guallabamba of Quito, the Chanchan of Alausi, and, farther south, 

 the Canar, Jubones, Tumbez, and Achira have all forced their way through the 

 western mountains, or rather, they have preserved their valleys despite the 

 upheavals and foldings in the neighbourhood of the seaboard. 



Thus the contrast between the two systems is very marked from the hydro- 

 graphic as well as from the geological point of view. But they resemble each 

 other in the volcanoes which have raised their superb cones above the vast 

 Ecuadorean pedestal. The transverse ridges connecting both Cordilleras from 

 the Colombian frontiers to the Cuenca basin also consist in a great measure of 

 eruptive cones. Ecuador, like south Colombia, is thus disposed by these 

 intermediate "rungs of the ladder " into so many separate basins, probably of 

 lacustrine origin, which stand at a mean altitude of about 8,000 feet, but the 

 •beds of which have been disordered by erupted matter and by erosion. 



* Travels amongst the Great Andes of the Equator, p. 335. 



