42G A. Blytt o?i the probable Cause of 



also fi probable supposition that the crust has not everywhere 

 the same power of resistance to the interior pressure, and 

 especiall}^ that the plastic mass may press in under the more 

 yielding parts of the surface. We have a striking example of 

 this in the laccolites noticed in North America. Eruptive matter 

 is here pressed up from below, and has lifted the beds into 

 dome-shaped vaults, so that the elevations have been different 

 in degree in different places, and greatest in the middle of the 

 domes. We nia}^ imagine that similar forces, but on a much 

 larger scale, have contributed to the elevation of Scandinavia, 

 — that Scandinavia is, sit venia vevbo, as it were a laccolite on 

 a larger scale. We must in the next place remember that the 

 changes of the earth's surface which have taken place in the 

 Tertiary and Quaternary periods, however great they seem to 

 be in our eyes, are inconsiderable in relation to the whole mass 

 of the earth. Even small forces, where they act upon a great 

 mass, may produce very considerable local effects, provided 

 that the changes do not everywhere occur upon the same scale. 

 If we consider that in this way the elevations are not every- 

 where equally great, then a depression of the equatorial belt 

 of only a couple of metres will suffice to cause many such 

 countries as Scandinavia to rise many metres, and there will 

 still remain pressure which is not exhausted. 



Of course it is not said that, whenever the eccentricity has 

 attained a high value, Scandinavia will rise to an equally great 

 amount. If the elevation has been great in a given period, 

 it is probable that the next period of elevation Avill have more 

 difficulty in upheaving the previously elevated land. The 

 position of the weakest points will vaiy. The next time, 

 perhaps, the elevation will chiefly affect other localities. If 

 we consider the Tertiary formations in Europe, we see that 

 the series of deposits is nowhere complete. It is only by com- 

 bining all the deposits formed at different places that we can 

 obtain a complete outline. In part this is certainly due to 

 the fact that the changes of form in the solid earth have not 

 taken place simultaneously everywhere. The great eccentii- 

 cities produced upheavals at different times in different places. 



There is, lastly, a circumstance of great importance which 

 may here be indicated, and which shows how quietly oscilla- 

 tions take place under normal conditions. Although according 



earlier periods of elevation. In the Bergen conglomerate, the old shales 

 are situated at a higher level, the further one goes from the shore. (See 

 Kjerulf, Udsigt over det sijdl. Norges Geologi, Christiania, 1879, pp. 154 

 -15(5, &c, ; and Helland in Arch.f. Math, og Nuturv. Bd. vi. Christiania, 

 1881, p. 222.) 



