168 AMtTND HELLAND ON THE EJORDS, LAKES, 



senting the level of the sea at the end of the Glacial epoch, have 

 not the same height? We must not conclude that the land in 

 Western Norway has risen only about 100 metres since the end of 

 the Glacial epoch, but in Eastern Norway 200 metres. A compari- 

 son of the present glaciation of Greenland with that of Norway will 

 show that this difference in the heights of the uppermost terraces 

 may be occasioned in another way. Terraces are found in Green- 

 land also at the mouth of rivers ; for example, there is a terrace 

 with marine fossils near Claushavn, in Disko Bay ; its height, how- 

 ever, is only 30 metres. Thus the level of Greenland was once 30 

 metres below the present one. We should then expect to meet 

 with a terrace of this elevation in many places in the fjords ; but 

 instead of this we find them filled with ice, which has prevented the 

 formation of terraces. Wherever a river issuing from a glacier is now 

 depositing the mud at its mouth a terrace is being formed at the 

 present sea-level. Suppose, then, that North Greenland were to rise 

 20 metres ; the terrace at Claushavn would be 50 metres high, and 

 those now formed at the mouth of the rivers would be 20 metres 

 high, while in the ice-fjords there would be none. Thus a diffe- 

 rence in the heights of the uppermost terraces does not necessarily 

 indicate that the amount of rise in the land has been different in 

 different places. The reason, then, that the terraces in Eastern Nor- 

 way overtop those in the western fjords by 100 metres may be that 

 the glaciers in the fjords of the latter prevented terraces being formed 

 when the land was 200 metres lower than at present ; only when 

 it had risen about 100 metres had the glaciers retreated sufficiently 

 to allow terraces to be formed in the fjord-valleys ; in these the 

 glaciers retired at different times, and the lowest terraces are found 

 in the valleys from which the glaciers last retired. Looking at the 



section of Lake Oifjordvand (fig. 4) the question naturally arises 

 with regard to the terraces at the lower end of the lakes, how, if 

 they are formed by the rivers from the loose detritus brought down 

 the valleys, has this been transported across the lake? This 

 has been explained by Professor Sexe*. The highest terrace in 

 front of the lake clearly cannot have been formed when a thick 

 glacier passed out into the fjord, nor can it have been formed when 

 the glacier had retired from the lake ; for then the detritus would 

 have filled up the basin. The terraces therefore must have been 

 formed when the glacier just reached the end of the lake. This is 

 evident from the fact that where detritus in front of a lake is more 

 than 100 metres above the sea (?'. e. higher than its former level) it 

 occurs not as a terrace, but as a. moraine. The geological structure 

 of the highest terraces is the same as that of the moraines ; they are 

 therefore only moraines made level by the waves of the sea. 



* Marker efter en Istid. 



