LAKES. 95 



metres above the level of the sea, consequently its basin, 

 over a great extent, is 330 metres (1110 feet) below the 

 level of the sea, which only attains to this depth in the 

 outer portion of the Christiania fiord. 



The Storsjo, in the valley of Rendal, has a length of 35 

 kilometres, and an area of 47 square kilometres* It empties 

 its waters into the Glommen. Its altitude is 257 metres, 

 its depth is 301 metres, its basin sinks 44 metres (147 

 feet) below the level of the sea, from which, by the course 

 of the Renelv and the Glommen, it is 340 kilometres 

 distant. 



The Tyri fiord, with an altitude of 64 metres, has a 

 depth of 281 metres, so that the bottom is 217 metres 

 (723 feet) below the level of the sea. 



Many small lakes situated near the interior extremity 

 of the deep fjords of the prefecture of Bergen and Roms- 

 dal have a depth as great as that of the fiords to which 

 they are adjacent. Thus the Horningdalsvand in the 

 prefecture of Romsdal, at an altitude of 56 metres, with 

 an area of 57 square kilometres, has a depth of 486 

 metres, so its bottom is 429 metres, 1,430 feet below the 

 level of the sea, from which it is distant only 10 kilometres. 

 On the south-west coast, in the low lying level country of 

 Jsederen, there are lakes oi fresh water, separated from the 

 sea by only banks of sand, with which they have nearly 

 the same level. The largest of them, the Orrevand, 

 measures 11 square kilometres. 



It may be premature to speak of the means by which 

 valleys of such depth have been dug, or ploughed out of 

 the solid earth. But the subject will not be overlooked ; 

 it will be discussed in the chapter entitled Mechanical 

 Action of Glaciers. Here it is deemed sufficient to 

 intimate that these are considered as valleys occurring in 

 the thalweg or bed of a river or a rivulet, which was filled 

 before the stream could continue its course beyond, and 

 which are kept full by supplies equivalent to some extent 

 to the current or delivery passing on. 



