INTRODUCTION. XXXI 



North of the city the resultant direction of the nearer chain and its several spurs in N.N.W. 

 as far as latitude 33" south, where it makes a hold sweep, first in a westerly, then in a south- 

 westerly, and, finally, in a south by west line, leaving the head of the basin some fifteen miles 

 across, and with a northerly hounding wall more than :>.ouo f.-.-t high. The last specified line 

 is followed by the chain to latitude 33 4CK, when it bends gradually to the eastward, and, in 

 latitude 34, approaches to the meridian of Santiago. Irregular and broken in its outline, this 

 western rim of the basin has several eminences exceeding 7,000 feet in height, is washed along 

 its northern half by the Colina, a tributary of the Mapocho, into which it empties twelve miles 

 west of Santiago, and is broken through by the Maypu, a bold mountain stream that crosses it 

 eighteen miles south of the city. From the issue of the Maypu on the basin to its penetration 

 of the western rim, is probably forty miles. Between that rim and the ocean another forty 

 miles in an air-line there is a less lofty range midway, and a country so broken that there is 

 but a small portion capable of cultivation under artificial irrigation. The southern glens and 

 higher slopes are partially covered with evergreen trees of small growth and shrubbery ; but 

 vegetation on most of those having northern aspects, and all level ground, is destroyed by heat 

 and want of moisture within two months after cessation of the showers in September. 



South of the city the culminating points of the nearer chain lie in a north and south line as 

 far as the river Maypu, from whence their general direction is inclined to the west until, in lati- 

 tude 33 50', the ridge curves quickly to the westward, and in 34 a prominent spur ap- 

 proaches to within sixty yards of the western range. These opposite eminences rise rapidly 

 from the plain to heights exceeding 1,000 feet above it, and the sides of the intervening gorge 

 continue parallel, though winding, through two or three hundred yards. Then, the mountain 

 slopes bend away again to the east and west, respectively, until the basin to the southward is 

 quite thirty miles broad, when their general southerly directions are resumed. This second 

 basin is somewhat similarly closed fifty miles S.W. of the Angostura de Payne, as the gorge is 

 called. 



A small stream of limpid water flows in a north-northwesterly course around the southern 

 base of the eastern spur, to a junction with a similar rivulet that descends from lower ranges of 

 the Andes along its northern declivity. The direction of the united streams from their conflu- 

 ence is N.W. until their waters fall into the Maypu at the base of the western Cordilleras. 

 Thus, the whole northwest, west, and southwest sides of the basin are bounded by water-courses ; 

 the Colina creek crosses it in latitude 33 15', and Payne creek (just referred to) in 33 50 7 , at 

 the base of the southern Andean bounding spur. 



Except in the glens between the spurs from both the eastern and western Cordilleras, there 

 are few indigenous trees on the basin. Disintegration of the granite largely entering into the 

 formation of the latter chain, has formed a soil upon its slopes on which scanty vegetation per- 

 petually thrives at a moderate elevation, whilst the Andean group, composed extensively of 

 stratified and columnar porphyries, offers to the sight long lines of blackened hills and crags as 

 denuded of herbage as at the hour when internal heat thrust them above the surrounding level. 

 Thirty years ago even the surface of the plain was cultivated only in the vicinity of the several 

 transverse streams, and there were neither fruit-bearing nor shade-trees, except in narrow 

 belts where supplies of water were accessible along their banks. Then, rains very rarely oc- 

 curred between the months of September and May ; and, under the joint powers of heat and 

 radiation to a constantly cloudless sky, ail the remaining portions were rapidly stripped of the 

 verdure that had thriven vigorously under the influence of winter showers. At that time, and 

 almost simultaneously, canals were cut along the base of the nearer range to convey portions of 

 the waters of the Maypu and Mapocho in a northerly direction, and slips of the Popvlits dilatata 

 were brought from Mendoza, a city on the eastern side of the Andes. A large volume of the water 

 taken from the former was emptied into the latter stream, and the whole supply extracted from the 

 latter was employed for irrigating fields north of Santiago. As both canals are above the gene- 



