The fjord glaciers in the west country were formed by the confluence of ice-streams from the upper valleys. These valleys, too, have everywhere acquired the same peculiar trough-shaped cross-section, where the sides curve together towards a flat bottom.
This glacial excavation further differs distinctly from the more even lines of river erosion in a longitudinal section. Each glacier works according to its own power, without being associated very closely in level with the branch valleys, as is always the case where running streams have produced the river beds.
In these deep west-country valleys, especially, it is noticeable how often the shape of the side valley opens out far up the slope of the side-wall of the main valley, so that the rivers must fall in rapids and waterfalls over this impediment.
Even if two glacier streams of equal power flowed together, it would be an exception if they had excavated to exactly the same depth; there are, therefore, continual ledges in the longitudinal section of the valleys, alternating with rapids and waterfalls.
All these characteristics are unknown in those countries where the rivers have had to make their own regular lines of fall, but they are always found in glacier-scored land.
There is not much room for extensive valleys on the narrow peninsulas between the fjords, nor is the distance between the head of the fjord and the watershed very great, being steep. The rivers are therefore short, although in many places the volume of water is comparatively large, owing to the heavy rainfall and, in spring and early summer, to the quickly-melting snow. Thus the depth of the fall down to the fjord head is very steep, and it is therefore here, where the mountain forms are grandest, that the waterfalls are most numerous, and where they are the highest.
Above the head of the fjord and the upper reaches of the branch fjords there exists in some places a corresponding series of lakes, or lake basins, at a height of some hundreds of feet above the fjord level.