TRANSACTIONS OF SECTION C. 661 



themselves before the epoch of suhmergence. But when we come to examine the 

 form of the channels, as shown by the soundings marked on the Admiralty- 

 charts, we find ourselves confronted by the remarkable fact that the beds of 

 the channels descend to very great depths, far exceeding those of the outlets 

 where the fjords open out upon the floor of the North Sea. Now as river vallevs 

 must necessarily increase in depth from their sources to their outlets, we are here 

 brought face to face with a physical problem which apparently is inconsistent 

 with our view of the original character of these channels as stated abov'e. To 

 the solution of this problem we must now shortly apply ourselves. 



2. General form of the fjord-beds. — The numerous soundings laid down on the 

 Admiralty charts of 1865 and 1886 enable us to determine with accuracy the form 

 of the submerged portions of the fjords. Using these soundings, and by their aid 

 laying down the isobathic contours, we arrive at results sufficiently remarkable. 

 In the case of the Hardanger, the Feris, the Sogne, the Nord, the Vartdals, and 

 the Stor Fjords with their branches we find that shortly after passing the entrance 

 from the outer sea and the chain of islands which fringes the coast of the mainland 

 they rapidly descend to great depths, which are continuous for long distances 

 inland, and then gradually become shallower toward the upper limits, where thev 

 pass into river valleys characterised by terminal moraines of ancient glaciers, or 

 old sea terraces. In carrying out the mapping of the contours the author has 

 adopted the following soundings : — 



(1) Those of the 100-fathom contour (600 feet). 



(2) „ ,. 200 „ „ (1,200 feet). 



(3) „ „ 400 „ „ (2,400 feet). 

 W „ „ liOO „ „ (3,600 feet), 



The floor of the Sogne Fjord descends to even greater depths than the 

 last of these, viz , 661 fathoms (3,966 feet), which is reached in the case 

 of the Sogne Fjord at a distance of about 25 miles from the entrance. At the 

 entrance the depth seldom exceeds 100 fathoms (600 feet), and is generally less ; 

 but once the deep water is reached there is little change of level for long distances. 

 As regards the cross-section of the principal fjords a glance at the charts shows 

 that they retain the form of narrow channels with little variation in breadth, 

 receiving tributaries on either hand and bounded by steep or precipitous walls of 

 rock, as in the case of the valleys, of which they are only prolongations under the 

 surface of the sea. 



3. When endeavouring to account for the peculiar form of the fjords and the 

 depth of their floors over the central portions we must not forget that these old river 

 valleys were the channels of great glaciers during the Post-Pliocene or Glacial 

 period, and that glacial erosion has contributed to the deepening process. Some 

 Norwegian geologists, such as Hausen,i attribute to this deepening of the original 

 channels by glacier erosion on the one hand, and to the piHng up of enormous 

 masses of moraine matter at the entrance on the other, the great disparity of the 

 depth of the fjords at the inner and outer stages of their course. To the latter 

 cause the author fully assents ; but he is doubtful whether glacier erosion has 

 had the effect of adding many hundreds of feet to the depth of the original floor 

 of the valleys. But leaving this question, we have to consider a second problem : 

 by what means did the original rivers empty themselves into the ocean before the 

 Glacial period, when there was neither deepening of the floor bv glacial erosion 

 nor shallowing by moraine matter ? Previous to the Glacial epoch the rivers 

 must, in the author's view, have entered the outer ocean through channels which 

 cannot nov/ be clearly traced by soundings over the shallow floor of the North Sea. 

 Atthe 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 



' Xunvny, edited by Dr. Sten Konow and Karl Fischer, May 1900. Translated 

 by J. C. Christie, Miss Muii', and others. 



1901. X X 



