In this part of its course the river receives from the south the streams, often intermittent, which rise on the northern slopes of the Stormberg, Zuurberg and Sneeuwberg ranges - the mountain chain which forms the water-parting between the coast and inland drainage systems of South Africa.
They form the backbone of the island, and crop out on the surface at intervals along the mountain chain which runs parallel to the west coast.
From the morphological point of view it is more important to distinguish the associations of forms, such as the mountain mass or group of mountains radiating from a centre, with the valleys furrowing their flanks spreading towards every direction; the mountain chain or line of heights, forming a long narrow ridge or series of ridges separated by parallel valleys; the dissected plateau or highland, divided into mountains of circumdenudation by a system of deeply-cut valleys; and the isolated peak, usually a volcanic cone or a hard rock mass left projecting after the softer strata which embedded it have been worn away (Monadnock of Professor Davis).
Concealed in part by later deposits, this ancient mountain chain extends from Castelnaudary to the neighbourhood of Valence, where it sinks suddenly beneath the Tertiary and recent deposits of the valley of the Rhone.
The usual habitat of lemmings is the high lands or fells of the great central mountain chain of Norway and Sweden, from the southern branches of the Langfjeldene in Christiansand stift to the North Cape and the Varangerfjord.
Wide, and is separated from the coast by a part of the mountain chain which extends along almost the entire water front of the republic. It is covered with well-cultivated plantations.
Outside the arc of the mountain chain no sign of this crumpling is to be detected except in the Salt Range, and the Peninsula of India has been entirely free from folding of any importance since early Palaeozoic times, if not since the Archean period itself.
From Bamian it passes over the central mountain chain to Kabul either by the well-known passes of Irak (marking the water-divide of the Koh-i-Baba) and of Unai (marking the summit of the Sanglakh, a branch of the Hindu Kush), or else, turning eastwards, it crosses into the Ghorband valley by the Shibar, a pass which is considerably lower than the Irak and is very seldom snowbound.
Smaller ranges run parallel to the main mountain chain in many places, and there are numerous isolated spurs which have no connexion with either.
It lies in the north-east trade winds belt, but the mountain chain on its northern frontier robs these winds of their moisture and leaves the greater part of the Brazilian plateau rainless.