6 DESCRIPTIVE GEOGRAPHY. 



they have been taught to associate with the former. At such times the mind unconsciously 

 seeks and clings to the marvellous in natural causes and effects, and imaginings are often given 

 to the press at home, to he converted into historic facts by those abroad. 



The passes of the Andes best known and most frequently travelled across are those of the 

 Cumbre and Uspallata, to the northeast, and the Piuquenes and Portillo ridges, to the southeast 

 of Santiago. The former is not so elevated, and the route to Mendoza is probably 50 miles 

 longer than by the latter ; but the casuchas (huts) for refuge, in case of snow-storms, and a 

 greater number of localities where scanty pasturage may be had, induce nearly all travellers to 

 prefer it; indeed, so great is the danger of a storm between the two ranges to be crossed on the 

 Portillo route, that, except for about two months of the summer, merchandise is never risked 

 over it. By the Cumbre pass the journey may be made from Santiago to Mendoza in six days, 

 the muleteers making every provision for the mountains prior to their departure from Santa 

 Eosa de los Andes. It is said to have been known to and constantly travelled by Peruvians, 

 who came to Aconcagua for supplies of grain, after Yupanqui annexed this portion of Chile to 

 his dominions ; and the arrieros (muleteers) have many traditions and local names which might 

 be received in confirmation of the assertion. Lieut. MacKae crossed it twice in prosecution of 

 his magnetical investigations, and his narrative gives full account of it. He found two roads, 

 traversable at different periods, according to the condition of the snow ; one, and that generally 

 crossed, 12,488 feet above the sea; the other, 12,656 feet. 



Except those whom necessity compels to make the journey, and the eemi-mensual courier with 

 the mail, few attempt to cross the Andes earlier than October or later than May. Arrieros can 

 be found ready to accompany you at all times ; but between these months they will demand triple 

 prices for the use of their mules, and the risk of precipices and starvation amid the snow is 

 fearful. 



The road to the Portillo pass winds up the valley of the river Maypu as far as its junction 

 with the Yeso, one of its principal affluents, and thence along the north bank of the latter 

 torrent through a basin-like valley with beds of pure gypsum, estimated at some 2,000 feet in 

 thickness. The river and valley take their name from these strata, though Mr. Pissis calls it 

 the valley of "Los Piuquenes" (Bernida melanoptera) . As far as this, the road is a constant 

 ascent, but good. Here begins the tiresome zig-zag climbing of the great cordillera, over strata 

 of porphyries, sandstones, conglomerates, and calcareous clay-slates, not unfrequently inter- 

 mixed with gypsum and marine fossils. Few ever reach its summit 13,189 feet* above the 

 sea without experiencing difficulty of respiration ; and the poor mules, scarcely less than the 

 masters whom they are serving. In Chile this sensation is called "puna;" in Peru, "veta," 

 "soroche," and "mareo," indifferently by natives and Creoles; its causes, in their ignorance of 

 the true one, being attributed to exhalations from metallic veins abounding in the Andes. At 

 times it is attended with a feeling of excessive lassitude and weariness, vertigo, temporary blind- 

 ness, and nausea, not unfrequently accompanied by bleeding from the nostrils and ears. All 

 are not subject to its influence, and there are evidently particular conditions of the system 

 when attacks are most liable. Onions and garlic are recommended by the arrieros as specifics, 

 though Dr. Darwin found nothing so effectual as the pleasure derived from the discovery of 

 fossil shells at this great height. Terrible winds prevailing in the Cordilleras, heat, and reflec- 

 tion of sunlight from the snow, are other sources of painful affliction. Every traveller com- 

 plains bitterly of these annoyances. These tempests usually continue from 9 or 10 A. M., until 

 late in the afternoon ; and so drying are they, that the skin cracks and bleeds ; and moisture is 

 so rapidly absorbed from deceased animals, that even the intestines do not rot. When Lieut. 

 MacKae reached the Cumbre, at 10^ A. M., the violence of the wind was such as almost to over- 

 turn both himself and mule ; and on his arrival at Mendoza, after eight days in the mountains, 

 his face and hands were so disfigured by scabs that he would scarcely have been recognised by 

 acquaintances. 



* See Lieutenant MacRae's narrative. 



