12 



A ELYTT. 



of a gradual and continuous process. The marks left by the 

 sea seem at first giance to corroborate the first of these theo- 

 ries. Thiis, in the lower parts of our valleys we find along the 

 river courses terraces of sand, pebbles, and clay, one behind and 

 above the other right up to the highest old shore line. The 

 terraces of which Kjerulf, preeminently amongst others, has 

 given us particulars, have an even surface and a steep declivity 

 outwards, against the mouth of the valley. They contain some- 

 times remains of sea animals. Under a higher level of the sea 

 the river carried down sand and gravel to its mouth, just as in 

 the present day banks and bars are forraed at the estuary of 

 our rivers. x\nd the terraces seem to indicate that the changes 

 in the level were broken by periods of rest. During the latter 

 the river had time to form a bank, which rose comparatively 

 rapidly; the next period of rest gave occasion to the formation 

 of another terrace, an so on. But this theory has to combat 

 many obstacles because the terraces lie often, as Prof. Sexe has 

 shown, even in valleys situated near each other, at different 

 elevations. This scientist is of opinion that steplike terraces 

 may be formed even under a gradual and steady rising, if the 

 carrying power of the river is subjected to changes. Our theory 

 may therefore probably also be applicable for explaining the 

 terraces because if long periods with milder climate have alter- 

 nated with others whose climate was more severe, it is evident 

 that the volume of the watei' and thus tlic car ry I ne/ power of 

 the cnrrcnt must have altered. Perhaps the rivers have at cer- 

 tain times carried down floating ice, at other not, and the thaw 

 in the spring must have increased the carrying power. We can 

 thus understand why the corresponding terraces in vallej^s near 

 each other do not always lie at the same elevation. Their rivers 

 differ in size, and when the carrjang power diminishes a big 

 river will retain the strength to form a terrace longer than a 

 small one. 



Besides these terraces, which are particularly conspicuous 

 in the short, steep valleys of the west coast of Norway and on 

 account of their regularity must excite the wonder of every 



