igsi. No. II. THE STRANDFLAT AND ISOSTASV. 225 



pressed more than loo metres and was probably covered b}' big glaciers 

 comparatively recently, and the extensive Justedal glacier still remains, 

 weighing down the land to some extent. In the region of Helgeland 

 where the outer coast was depressed more than 75 metres, there mav 

 also have been a glacial covering comparatively recently, remnants of 

 which still exist in the big "Svartisen" glacier. 



Another fact which nia\- also have retarded the upheaval of the crust 

 in this region, is that the extensive submerged strandfiat was covered 

 during the depression by a layer of water as much as 75 metres deep or 

 even more near its inner margin, and the weight of this water made the 

 upheaval of the land slower. It may, therefore, not seem improbable that 

 in Helgeland, as well as in inner Sogne Fjord, the upheaval of the land 

 may still be a few metres short of its full coniylciion, while it is long ago 

 completed along the outer west coa-f ." -nuthern Norway as well as in 

 Lofoten and \'esterålen where the late-glacial depression was verv small 

 or nothing at all, and where there was no extensive area of submerged 

 oea-floor outside that should be elevated. 



The Nature of the Rocks and the Topography of the Strandflat 

 and the Continental Shelf. 



Our investigations have shown that the .shape and development of 

 the strandflat vary to some extent with the nature of the rocks. This is 

 especially conspicuous in the topographv of the submerged strandflat of 

 Norway. 



\\'here the rocks possess comparatively less power of resistance to 

 erosion, the submerged strandflat has a very level surface forming a 

 nearly horizontal plane only some few metres below present sea-level, 

 and its edges are sharply defined at about the same depth. Its side slopes 

 are often steep descending to considerable depths on the continental shelf 

 outside. 



Where the rocks possess a comparatively great power of resistance 

 to erosion, the surface of the submerged strandflat is considerably more 

 uneven and irregular. It is generally sloping seawards, its edges are less 

 sharply defined, and its depth may vary a great deal. Its outer side slopes 

 are as a rule not steep, and the depth of the continental shelf outside not 

 considerable. 



If this be compared with the surface of the continental shelf of 

 Norway outside the strandflat, we finrl a striking difference. 



In regions of weaker rocks the continental shelf is broad, but is 

 comparatively uneven and its ^^urface is to a great extent lying at a con- 

 sideral)le depth below present sea-level, while, as we have seen, the sub- 

 merged strandflat is extremely level in those regions, and is standing 

 comparatively high, being near present sea-level. 



Vid.-Selsk. Skrifter. I. M.-X. Kl. 1921. No. 11. 15 



