This range forms, in a measure, a natural boundary between Sweden and Norway from the extreme north to the north of Svealand, the central of the three main territorial divisions of Sweden (Norrland, Svealand and Gotaland); though this boundary is not so well markd that the political frontier may follow it throughout.
Sweden itself may be considered in four main physical divisions - the mountains and highland district, covering all Norrland and the western part of Svealand; the lowlands of central Sweden; the so-called Sma.land highlands, in the south and southeast; and the plains of Ska.ne, occupying the extreme southward projection of the peninsula.
A local increase of the ice period naturally takes place in the upper parts of the Smaland highlands; and in the case of the great lakes of Norrland, the western have a rather shorter ice period than the eastern.
Thus the average in the north of Norrland is 16.53 in., in the south of Norrland 22.6 in.
The fir (Pinus sylvestris) and pine (Pinus abies) are the predominating trees Spruce is common, and even predominates in the higher parts (between the great valleys and immediately below the birch-belt) in the north of Norrland.