Page:Quarterly Journal of the Geological Society of London, vol. 33.djvu/204

166 166 AMUND HELLAND ON THE FJORDS, LAKES,

fjords up the valleys, finds the beds of the latter, to an extent vary- ing from 1 to 8 kilometres, covered by loose detritus lying in the form of terraces, one above the other, on both sides of the river, con- sisting of boulders, gravel, sand, and sometimes a little clay. After passing this tract deep lakes are met with in many places ; and before the lower end of these the loose materials are often arranged in a moraine, which runs at right angles to the longer axis of the lake. By looking at the section (fig. 3) of the terrace and moraine in front of Lake Sandvenvand in Odda, in Hardanger, we see that immediately about the end of the fjord several terraces occur in quick succession, and that these are terminated in a moraine dam- ming up the lake, which is so deep that its bottom is below the sea- level. The terraces in advance of the lakes in the fjord-valleys of Western Norway never attain an elevation of much more than 100 metres above the sea, and the height of these lakes is always less than 100 metres. If we proceed to the upper end of the lakes ter- races are sometimes found there also. The same features (terraces in advance of lakes) are also found in South-eastern Norway, in front of the largest lakes in Norway. Also both east and west of Christiania Fjord the same relations between rows of moraines and rows of lakes are found to exist. I have visited and sounded more than thirty-eight lakes with moraines and terraces in front of them, and in most of them can directly demonstrate that, although dammed up by the moraines and terraces, they are also true rock-basins ; and I have only some doubt in this respect in the case of a few small lakes. It would be tedious to describe all these lakes with their moraines and terraces, because it would be a repetition of the same thing in substance with slight variations in detail ; so I will confine myself to a few instances. In the case of Lake Sandvenvand, already men- tioned, the section (fig. 3) gives the height of the terraces and of the moraine directly in front of it. No rock is visible between the lake and the sea, the terraces covering the whole valley ; the bed of the lake as shown in the section is 30 metres below the sea-level. Near Lake Oifjordvand, also in Hardanger (fig, 4), there is a series of terraces, the highest of which is situated immediately in front of the lake, without any moraine ; near to where the river issues from the lake the solid rock protrudes, being here covered with groovings. Thus the lake is a true rock-basin. The deepest lake in Norway which has been sounded is Horningdalsvand, in Nord- fjord (fig. 5). The solid rock is seen near the lake and the terraces. A comparison of the measurements of the highest terraces before the lakes will show that these vary to no small amount. The high- est terrace before the Horningdalsvand is only 71 metres, while that before Lake Vasbygdvand, in Sogn, is 108 metres, and the highest terraces before the lakes in South-eastern Norway extend up to 200 metres. As many of them contain marine fossils, they have evidently been formed under the sea, and the horizontal sur- face of the highest shows the level of the sea during their formation. How are we to explain the fact that these terraces, though repre-