CHAP. XVI. OSCILLATIONS OF LEVEL. 335 



hundreds of miles apart; so that, instead of the hind sub- 

 siding five feet in a hundred years, as at the North Cape, it 

 becomes less than the same number of inches at Stockholm, 

 and farther south the land is stationary, or, if not, seems 

 rather to be descending than ascending.* 



To cite an example of high geological antiquity, M. Hebert 

 has demonstrated that, during the oolitic and cretaceous 

 periods, similar inequalities in the vertical movements of 

 the earth's crust took place in Switzerland and France. By 

 his own observations and those of M. Lory, he has proved 

 that the area of the Alps was rising and emerging from 

 beneath the ocean towards the close of the oolitic epoch, and 

 was above water at the commencement of the cretaceous era ; 

 while, on the other hand, the area of the Jura, about one 

 hundred miles to the north, was slowly sinking at the close 

 of the oolitic period, and had become submerged at the com- 

 mencement of the cretaceous. Yet these oscillations of level 

 were accomplished without any perceptible derangement in 

 the strata, which remained all the while horizontal, so that 

 the lower cretaceous or neocomian beds were deposited con- 

 formably on the oolitic.f 



Taking for granted, then, that the depression was more 

 rapid in the more elevated region, the great rivers would 

 lose, century after century, some portion of their velocity 

 or carrying power, and would leave behind them on their 

 alluvial plains more and more of the moraine-mud with 

 which they wei^e charged, till at length, in the course of 

 thousands or some tens of thousands of j^ears, a large part of 

 the main valleys would begin to resemble the plains of Egypt, 

 where nothing but mud is deposited during the flood season. 

 The thickness of loam containing shells of land and amphi- 



* Principles of Geology, chap. xxx. de France, 2 series, torn. xvi. p. 596, 

 9th ed., p. 519 et seq. 1S59. 



f Bulletin de la Societe Geologique 



