THE SURFACE OF THE GLOBE. 8^ 



present state, we find that the shore has gained more than six thou- 

 sand fathoms since 1604, which is an average of one hundred and fifty 

 or one hundred and eighty, and in some places, two hundred feet per 

 annum. The Adige and Po are now more elevated than all the land 

 which lies between them ; and it is only by opening again new chan- 

 nels in the low lands which they formerly deposited, that we can 

 avert the disasters with which they now threaten us. 



The same causes have produced the same effects along the branches 

 of the Rhine and the Meuse ; and thus the richest districts of Holland 

 have perpetually before them the frightful sight of their waters sus- 

 pended above their soil, at a height of twenty or thirty feet. 



M. Wiebeking, director of the bridges and roads in the kingdom of 

 Bavaria, has written a memoir on this progress of things, so important 

 to be well understood by the people and the government, in which he 

 shoAvs that this property of elevating their beds belongs more or less to 

 all rivers. 



The accumulations along the coasts of the North Sea are not less 

 quickly formed than in Italy. We can easily trace them in Friesland 

 and in Groningen, where the first dykes were constructed by the 

 Spanish governor, Gaspar Robles, in 1570. A century afterwards 

 land had been formed in some places three quarters of a league beyond 

 these dykes ; and the city of Groningen itself, partly built on the 

 ancient soil, on a limestone which does not belong to the present sea, 

 and in w T hich we find the same shells as in our coarse limestone in the 

 neighbourhood of Paris, is only six leagues from the sea. Having visited 

 these places, I can myself testify other well-known facts, the greater 

 portion of which M. Deluc has already ably explained*. The same 

 phenomenon may be observed, and with the same exactitude, along 

 the coasts of East Friesland, and the countries of Bremen and Holstein, 

 because the parts are known where the new lands were enclosed for 

 the first time, and thence we can measure what has since been gained. 



This alluvial plain, so very fertile, formed by the rivers and the sea, 

 is in this country a gift the more valuable, as the ancient soil, covered 

 with heath and turf-bogs (tourbieres) is incapabie of being made to 

 produce vegetation ; the alluvial deposites alone supply the means of 

 subsistence to the inhabited cities established along this coast since the 

 middle age, and which would not have reached their present opulent 

 state without the rich lands which the rivers produced for them, and 

 which they are continually augmenting. 



If the extent which Herodotus assigns to the sea of Azof, which he 



* In various parts of the two last volumes of his Letters to the Queen of England. 



