Professor E. Hull — On tlie Norwegian Fjords. 557 



author's view, have entered the Arctic Ocean through channels which 

 cannot now be clearly traced by soundings over the shallow floor of 

 the North Sea. At the same time it is certain that it was by such 

 channels that they reached their ultimate destination in the Arctic 

 Ocean, because rivers as they flow seawards must necessarily descend 

 to lower levels. This being so, it follows that the channels do 

 actually exist, though they may not be traceable by the soundings 

 over the flow of the comparatively shallow North Sea ; and we have 

 now to consider why it is that they are untraceable. 



The cause appears to be closely connected with the subsequent 

 submergence in later or post-Glacial times, as indicated by the raised 

 beaches and terraces.^ During this epoch the glaciers had only 

 partially disappeared or receded from the lower valleys. Great 

 quantities of mud, sand, gravel, and boulders would thus be carried 

 down by the streams and distributed by floating ice over the sea-bed. 

 By such material the whole floor of the North Sea has been overspread 

 to unknown depths, and owing to the agency of tides and currents 

 may have been swept into the deep channels of the pre-existing 

 rivers. The author is convinced that, were it possible to strip the 

 floor of the North Sea of its sedimentary covering, these channels 

 would be found traversing the floor of the continental platform, and 

 ultimately opening out by caiion-like channels on the floor of the 

 Arctic Ocean. 



The phenomena here observed, or inferred, have their representa- 

 tives along the coasts of the British Isles and Western Europe. In 

 both cases there is the shallow continental platform, terminating in 

 a deep and rapid descent to the floor of the abyssal ocean, and 

 traversed by channels of ancient rivers traceable by the soundings 

 in the case of Western Europe, or inferential in the case of Western 

 Scandinavia. In a few cases these channels are for short distances 

 clearly indicated on the charts ; as, for example, in the case of the 

 Bredsund Dybet, which is a prolongation of the Stor Fjord out to 

 sea, between the islands of Godo and Harejdo in lat. 62° 30', with 

 a general depth of 100 fathoms below the adjoining floor of the sea ; 

 and there are a few other similar cases. 



Outline of the physical history of the fjords. — As connected with 

 the past history of the Norwegian fjords the following appear to be 

 the most important stages : — 



1st (Earliest) Period. — Continental conditions ; Archsean rocks ; 

 river ei'osion begins. 



2nd Period. — Partial submergence in early Silurian times. 



3rd Period. — Elevation of land during Mesozoic and Tertiary 

 periods ; further deepening of river channels. 



4th Period. — Quaternary. Early Glacial ; great elevation of land 

 and ultimate extension of snowfields and glaciers. Ice filling the 

 valleys and moving out to sea. 



^ According to Professor Reusch the terraces with mariuc shells reach an elevation 

 of about 200 metres (656 feet) in the Trondhjem district; but the author during 

 a recent visit was unable to observe any higher than 250 feet south of this position. 



