The region drained by a river system
The line of the highest summits and of the watershed ranges is about 30 to 40 m.
"North of the principal watershed forest trees and general verdure refresh the eye.
The lake in Peru which is third in size is that of Parinacochas on the coast watershed, near the foot of the snowy peak of Sarasara.
It surmounts the watershed by means of Sapperton tunnel, 2 m.
The present caravan road keeps the high ground to the west near the watershed, and avoids the Pass of Michmash altogether.