The snowclad Andi ridge, belonging to the system of transverse upheavals which cross the Caucasus, branches off the latter at Borbalo Peak (10,175 ft.), and reaches its highest altitudes in Tebulosmta (14,775 ft.) and Diklos-mta (13,740 ft.).
Although only one or two peaks reach the line of perpetual snow, several of the loftiest summits are snowclad during the greater part of the year.
After flowing southward along the base of the high Andes for a short distance and receiving a number of torrents from the snowclad heights, it turns south-eastward across the plain and enters the Maranon about 70 m.
Above the town to the north rise the snowclad peaks of the Bernina group. The railway goes on to Tirano, 16 m.
Overlooking the plateau from the west are the snowclad peaks of Pomarape (20,505 ft.), Parinacota (20,918 ft.), Sajama (21,047), Huallatiri (21,654), Lirima (19,128), and the three volcanic peaks, Oyahua (19,226), San Pedro y Pablo (19,423) and Licancaur (19,685).
Above these are cool, temperate slopes and valleys, and high above these, bleak, wind-swept passes and snowclad peaks.
Above sea-level; and its climate is cold and unpleasant, owing to the winds from the neighbouring snowclad heights, and the barren, pumicecovered table-land on which it stands.
Fully one-half of its length is through the mountainous districts of central Bolivia, where it is fed by a large number of rivers and streams from the snowclad peaks, and may be described as a raging torrent.
During the coldest winter months their communications are much easier with Spain than through the snowclad passes leading into Ariege.