I92I. No. II. THE STRAXDFLAT AND ISOSTASY. I7 



It has, huwcver. to he considered tliat the suhaërial denudation is 

 working, not only in the coastal region, like the marine denudation, hut 

 over the whole land surface simultaneously. As will be mentioned in a 

 later chapter, the resulting removal of rock from this great area, will 

 necessarily cause a corresponding isostatic elevation of the land, and this 

 will change the above process. In stead of the three stages a b, c d, and e f 

 of Fig. 4, we will find that when the land surface was denuded, from a b 

 to c d the land would be elevated very nearly the same he'ght, ;'. c. the 

 shore-line in Fig. 5, would stand at S"L' in stead of at 5 L, in relation 

 ID the land, and the coastal plain would be developed to form th? profile c /;. 

 The rock-surface would then follow the line g'h c d. 



When the land surface is denuded to e f, the land will rise so much 

 that the shore-line will be lowered to S" L" in relation to the land. The 

 coastal plain will be developed to form a slope as indicated by the line i e. 

 As the sea floor has not been eroded, it should not be elevated, onlv its 

 inner part g"i will be raised with the rising coast, owing to the rigidity 

 of the earth's crust. 



The final result will be that the slope of the land, the coastal plain, 

 and the slope of the sea floor will be something like what is represented 

 by the line g"icf with sea-level at S" L" . 



It might be objected that the coastal region g"i e will thus be elevated 

 above its earlier level. It has, however, to be considered that this zone is 

 lifted with the whole land, and the surplus of mass elevated in the coastal 

 zone, above and below sea-level, is more than compensated for bv the 

 defeceit of mass elevated in the region of the land inside. 



The coastal plain resulting from this process will rise inland, and 

 will be continued in the land slope with a perfectly gradual transition 

 between them, as demonstrated by Fig. 5. 



A last upheaval of central and western Norway, in relation to 

 sea-level, may perhaps have ocurred in earl}- Tertiary time (Eocene), or 

 may have been finished in Miocene. During the many millions of years 

 since then, the subaërial denudation has been working continually on the 

 surface of Norway. 



During this long time the coast land has probably been much denuded, 

 and a plain with a fairly gentle slope may have been more or less developed 

 by the process described above. But a low foreland, similar to the strand 

 flat, could not be developed in this manner, except perhaps in regions 

 where the coastal border is Iniilt up of rocks with relatively littl-? power 

 of resistance. Rut even there the surface could hardlv be planed so verv 

 flat by this process alone. 



If the shore-line oscillated vertically during this long preglacial time, 

 and provided that there had been no marine denudation, the slope would 

 become steeper in the outer coast land which by submergence had been 

 less exposed to the subaërial denudation. 



Vid.-Selsk. Skrifter. I. M.-N. Kl. 1921. No. 11. 2 



