2) 
58% 
TF 
MOVEMENT OF DUNES. 
cavity is opened into them toa considerable depth, thereby 
giving the wind access to the interior, where the sand is thus 
first dried, and then scooped out and scattered far over the 
neighboring soil ‘The dune is now a magazine of sand, no 
longer a rampart against it, and mischief from this source seems 
more difficult to resist than from almost any other drift, be- 
cause the supply of material at the command of the wind is 
more abundant and more concentrated than in its original thin 
and widespread deposits on the beach. The burrowing of 
conies in the dunes is, in this way, not unfrequently a cause of 
their destruction and of great injury to the fields behind them. 
Drifts, and even inland sand-hills, sometimes result from 
breaking the surface of more level sand deposits, far within 
the range of the coast dunes. Thus we learn from Staring, 
that one of the highest inland dunes in Friesland owes its 
origin to the opening of the drift sand by the uprooting of a 
large oak.* 
Great as are the ravages produced by the encroachment of 
the sea upon the western shores of continental Europe, they 
have been in some degree compensated by spontaneous marine 
deposits at other points of the coast, and we have seen in @ 
former chapter that the industry of man has reclaimed a large 
territory from the bosom of the ocean. These latter tri- 
umphs are not of recent origin, and the incipient victories 
which paved the way for them date back perhaps as far as ten 
centuries. In the meantime, the dunes had been left to the 
operation of the laws of nature, or rather freed, by human 
imprudeuce, from the fetters with which nature had bound 
them, and it is scarcely three generations since man first 
attempted to check their destructive movements. As they 
advanced, he unresistingly yielded and retreated before them, 
and they have buried under their sandy billows many hun- 
dreds of square miles of luxuriant cornfields and vineyards and 
forests. 
On the west coast of France a belt of dunes, varying in 
* De Lodem van Nederland, i., p. 425. 
