ON THE MOVEMENTS OF THE EARTh's CRUST. 343 



is also a probable supposition that the crust has not every where the 

 same power of resistauce to the interior pressure, and esi)ecially that 

 the plastic mass may i^ress in under the more yielding- parts of the sur- 

 face. We have a striking exami)le of this in the laccolites noticed in 

 North America. Eruptive matter is here pressed up from below, and 

 has lifted the bed into dome-shaped vaults, so that the elevations have 

 been difterent in degree in different places, and greatest in the middle 

 of the domes. We may imagine tliat similar forces, but on a much lar- 

 ger scale, have contributed to the elevation of Scandinavia; — that Scan- 

 dinavia is, sitvcnia verba, 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, how- 

 ever 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 everywhere equally 

 great, then a depression of the equatorial oelt of only a couple of meters 

 will suffice to cause many such countries as Scandinavia to rise many 

 meters, 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 equall}^ great amount. Tf the 

 elevation has been great in a given period, it is probable that the next 

 period of elevation will have more difficulty in upheaving the previously 

 elevated land. The position of the weakest points will vary. The next 

 time, perhaps, the elevation will chiefly afiect other localities. If we 

 consider the Tertiary formations in Europe, we see that the series of 

 deposits is nowhere complete. It is only by combining 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 ec- 

 centricities produced upheavals at different times in different places. 



There is lastly a circumstatice of great importance which may here 

 be indi<!ated, and which shows how quietly oscillations take place under 

 normal conditions. Although according to our hypothesis, the radii of 

 the higher latitudes constantly lengthen, wliile those of lower latitudes 

 are shortened, yet through long geological periods coast-lines return re- 

 peatedly, during their displacements, to their old iiosition. Thus A. de 

 Lapparent {Bull. Soc. Geol. France, ser. 3, vol. XV. p. 400) says : " I have 

 indicated, in the Cotentii:, an agreement between the actual shores and 

 those at which the sea stopi)ed at various epochs of geological history. 

 I have there shown shorelines reproduced, almost witliout variations of 

 altitude, in the Hettangian, Sinemurian, Liassian, Cenomanian, Danian, 

 Parisian, Tongrian, Pliocene, and present epochs, - - - and that 

 eight or nine times at least, since the Priuniry era, the coincidence of 

 the shores has been reproduced at the same point: " and in the same 



