174 AMUND HELLAND ON THE FJORDS, LAKES, 



other forces beside the quantity of ice and water have determined 

 the depth reached by erosion ; but generally it may be said that 

 valleys draining large districts of rainfall have a large transverse 

 section. If a glacier fills a tributary valley, and is thinner than 

 that in the main valley, the depth to which it erodes its bed must 

 be less than the depth of the main valley. Hence many tributary 

 valleys must debouch high above the bottom of the main valley. 

 Instances abound of tributary valleys debouching thousands of feet 

 above the beds of the main valleys, along the steep sides of the 

 fjords of Western Norway. As mentioned above, we are unable to 

 draw an exact line between the work of rivers before the Glacial 

 epoch and that of glaciers during it. 



The following, then, is the history of the configuration of Norway. 

 The land is formed of rocks different in composition and origin, for 

 which reason the country from the first has had a very uneven 

 surface. On this thousands of rills and rivers began their work, and 

 previous to the Glacial epoch eroded valleys more or less deep and 

 broad. During it the glaciers followed, on the whole, the course of 

 these, enlarging and shaping them, and excavating the fjords 

 and lakes. 



The occurrence of many large deep fjords in Western Norway is 

 a consequence of their glacial formation and of the climate of the 

 country ; for on the west coast the rain- and snow-fall is very con- 

 siderable, and the land slopes rapidly to the sea. Hence the thick- 

 ness and velocity of the glaciers were probably very considerable 

 here. Further, they seem to have remained longer on the west 

 coast. If the fjords and lakes of Norway are formed by glacier- 

 erosion they must be confined within the limit of glaciers. As 

 these, however, once extended over the whole country, it has 

 everywhere fjords and lakes. If at the end of the Glacial epoch 

 the glaciers halted for long intervals at various places, we ought to 

 find marks of erosion corresponding with these limits. We have 

 already shown that we do so find them. When thick glaciers descen- 

 ded into the fjords and constantly deepened their beds, very peculiar 

 relations of depth would be caused in the fjords. The glacier of 

 the main fjord was constantly increased on its way by supply from 

 tributary fjords, in consequence of which the depth or breadth of 

 the fjord must have been increased. As the glacier proceeded further 

 down the fjord the loss from melting would exceed the supply from 

 the sides ; and thus its erosive power, and consequently the depth of 

 the fjord, would decrease ; but while the glaciers deepened the bottom 

 of the fjords, the depth of the sea in front of them would be dimi- 

 nished, as all the detritus would be deposited there. 



Our theory, then, requires : — (1) the depths in the fjords should be 

 greater than in the sea ; (2) the depth of the fjord should increase 

 towards the inner part and decrease towards the mouth; (3) great 

 masses of boulders, gravel, and mud should be found in the sea in front 

 of the fjords. These requirements are satisfied by the observed facts. 

 It is well known that great depths occur in the Norwegian fjords. 

 While soundings of from 400 to 500 metres are very frequent in the 



