130 THEORY OF THE EARTH. 



hundred years afterwards, land had already been 

 gained, in some places, to the extent of three 

 quarters of a league beyond these dikes ; and even 

 the city of Groningen, partly built upon the old 

 land, on a limestone which does not belong to the 

 present sea, and in which the same shells are 

 found as in the coarse limestone of the neighbour- 

 hood of Paris, is only six leagues from the sea. 

 Having been upon the spot, I am enabled to ad- 

 duce my own testimony in confirmation of facts 

 already well known, and which have been so well 

 stated by M. Deluc *. The same phenomenon 

 may be as distinctly observed along the coasts of 

 East Friesland, and the countries of Bremen and 

 Holstein, as the period at which the new grounds 

 were inclosed for the first time is known, and the 

 extent that has been gained since can be measured. 

 This new alluvial land, formed by the rivers and 

 the sea, is of astonishing fertility, and is so much 

 the more valuable, as the ancient soil of these coun- 

 tries, being covered with heaths'and peat-mosses, is 

 almost everywhere unfit for cultivation. The allu- 

 vial lands alone produce subsistence for the many 

 populous cities that have been built along these 

 coasts, since the middle age, and which perhaps 

 would not have attained their present flourishing 

 condition, without the aid of the rich deposits 



* In various parts of the two last volumes of his Letters 

 to the Queen of England, . 



