296 FKiDTjoF nansp:n. M.-X. Kl. 



1I1C slraiKl t'l.'il lias rctunicil lo its jjrcvioiis liorizontal lc\cl in tlie outer 

 regions alont; llie coast, wlnle in tlic iniur regions of the fjords, and 

 perhaps als(j along tlie coast of lielgcland, there may perhaps he some 

 few metres left before this le\el is atlained. At the same tiine, however, 

 the stranflflat as a whole is now standing perhaps 10 to 17 metres rela- 

 ti\(,l\ higher above sea-level, than it did before the submergence, which 

 may at least to some extent be due, as was previously mentioned, to a 

 vertical nio\'ement (;f sea-level. 



'J'he different levels of the extensive strandfiat of Norwa}' prove 

 that the Norwegian coast must liave stood at these levels during very 

 long periods before the last submergence, and probably even in preglacial 

 time, and it seems ])robable that after each submergence during the 

 different glacial periods, the earth's crust has returner] to the horizontal 

 level of the strand flat. 



A natural conclusion must then be that the level of the strandfiat 

 represented the level of isostasy at times when the land was not depressed 

 by the load of the ice-caps; for otherwise it seems to be inconceivable 

 why the crust should always return to the same horizontal level after 

 each depression. 



The crust in these regions is to a great extent built up of very old 

 Archæan rocks, while in others, especially in northern Norway, there are 

 younger formations, but they all show the same horizontal levels of the 

 strandfiat and very nearly the same relative degree of submergence. 



Moreover this is a region of exeptionally stable and tranquil character. 

 During the long ages since the great Caledonian mountain-folding at the 

 end of Palæozoic time, there has been singularly little crustal movement 

 in the region of Fenno-Scandia. Besides, the Pleistocene age has certainly 

 not been a period of special crustal mobility in any parts of the globe. 



When we, nevertheless, find that during the tranquil Pleistocene 

 period this stable part of the earth's crust has been so responsive to the 

 load and removal of the last, not very extensive, ice-sheet of Fenno- 

 Scandia, as well as those of each previous glacial period, and the sinking 

 and rising movements have proceeded so continuouslv, and have been so 

 regularly distributed over the whole area concerned, as is proverl by the 

 raised beaches, the relation between the heights of the upper limit of 

 submergence and the Tapes-line &c., and l)y the strandfiat — then a logical 

 conclusion obviouslv is that this cannot be due to a special quality of an 

 exceptionally flexible or mobile area of the earth's crust, but must indicate 

 a general quality of the lithosphère, nor can the isostatic crustal move- 

 ments be limited to periods of special crustal mobility. 



We may, therefore, infer that the earth's crust is on the zvhole very 

 responsive to disturbances of its cquilil^riuni. and has a great ability to 

 re-establish it. After a sufficient time it «';'// attain its lei'cl of isostasy 

 at least zvithin some few metres. 



