434 SAND-PLAINS OF BELGIUM. [April 



especially on the Landes of the Gironde, and generally on the shores 

 of the Bay of Biscay. 



On the island of Sylt, the dunes reach a height of from 100 to 120 

 feet above the level of the sea, and they fringe the land to a breadth 

 of from 160 to 240 fathoms; where at places from the contraction 

 of the coast, there exist only a single range of sand-hills, the breadth 

 is reduced to from 24 to 80 fathoms. 



The Lister - duncn, however, must also be taken into account. 

 These constitute often a formal range of hills interpenetrated by 

 valleys and hollows, which is more than two miles in width. 



In Jutland, the sand-hills attain a height often of 200 feet. On 

 the other islands of the German Ocean the dunes are less imposing, 

 — on Helgoland, for example, they do not exceed from 25 to 30 feet 

 in height, and they form a fringe rarely exceeding 50 fathoms in 

 breadth. 



In the Baltic the sand-hOls attain a height in most of 30 feet, 

 but sometimes they can reach a height of from 100 to 126 feet, 

 and in some exceptional cases so much as 180 feet above the level 

 of the sea. The breadth of the dune range, reaching here and there 

 only to 50 fathoms, extends in other places to from 240 to 300 

 fathoms, and reaches even a breadth of 520 fathoms. And if we 

 include the older dune-formations now covered with vegetation, it 

 shows a breadth very far exceeding this. 



The strand-dunes of the French Landes, stretching 140 miles 

 along the coast, have by drifting attained the unusual breadth of 

 from 1000 to 5000, or a mean of 2500 fathoms; the elevation of 

 the dunes above the sea- level ranges from 12 to 150 feet; the 

 average has been given as 57 feet. 



" Looked at from the sea, a range of dunes extending to the distant 

 horizon appears to the spectator like a range of hills, and the sharp 

 outline of these reminds him more of hills of porphyry than of a 

 mobile outline hewn out of sand by the wind. Towards the sea, 

 these heights are broken off by the waves into steep walls; toward 

 the land, they slope away, as do all dunes under the wind, to one 

 only of about 3 0°. They never form continuous chains of the same 

 height, but always raise themselves as higher or lower elevations 

 connected with one another, which are separated by less elevated 

 valleys. 



" Entering the range, and contemplating the dune system, a two- 

 fold arrangement is perceptible — long valleys, which run parallel 

 with the coast, and divide the mass of dunes into some parallel 

 rows ; and cross valleys, which cut up these rows of dunes into 

 single hillocks. 



" The height of the dunes, as has just been shown, is very varied. 



