566 DUNES OF PRUSSIA. 



A range of dunes extends along the whole •western coast of 

 Jutland and Schleswig-Holstein, and the movement of these 

 sand-hills was formerly, and at some pomts still is, very destruc- 

 tive. The rate of eastward movement of the drifting dunes 

 varies from three to twenty-four feet per annum. If we adopt 

 the mean of thirteen feet and a half for the annual motion, these 

 dunes have traversed the widest part of the belt in about twenty- 

 five hundred years. Historical data are wanting as to the period 

 of the formation of these dunes and of the commencement of 

 their drifting; but there is recorded evidence that they have 

 buried a vast extent of valuable land within three or four cen- 

 turies, and further proof is found in the fact that the movement 

 of the sands is constantly uncovering ruins of ancient buildings, 

 and other evidences of human occupation, at points far within 

 the present limits of the uninhabitable desert. Andresen esti- 

 mates the average depth of the sand deposited over this area at 

 thirty feet, which would give a cubic mile and a half for the total 

 quantity.* 



The drifting of the dunes on the coast of Prussia commenced 

 not much more than a hundred years ago. The Frische [N^ehrung 

 is separated from the mainland by the Frische Haff, and there 

 is but a narrow strip of arable land along its eastern borders. 

 Hence its rolling sands have covered a comparatively small extent 

 of dry land, but fields and villages have been buried and valuable 

 forests laid waste by them. The loose coast-row has drifted over 

 the inland ranges, which, as was noticed in the description of 

 these dunes on a former page, were protected by a surface of dif- 

 ferent composition, and the sand has thus been raised to a height 

 which it could not have reached upon level ground. This eleva- 

 tion has enabled it to advance upon and overwhelm woods, which, 

 upon a plain, would have checked its progress, and in one in- 

 stance a forest of many hundred acres of tall pines was destroyed 

 by the drifts between 1804 and ISST.f 



* Andresen, Om Klitformationen, pp. 56, 79, 82. 



f Stoppani, Corso di Oeologia, i., ff. 154, says there are dunes 100 metres high. 

 At the mouth of the , and they have advanced a mile in twenty years. 



