582 USE OF DUNES AS A BARRIER AGAINST THE SEA. 
the sea-sand tends to accumulate upon the coast of Schleswig- 
Holstein and Jutland, and were there no conflicting influences, 
the shore would rapidly extend itself westwards. But the 
same waves which wash the sand to the coast undermine the 
beach they cover, and still more rapidly degrade the shore at 
points where it is too high to receive partial protection by the 
formation of dunes upon it. The earth of the coast is general- 
ly composed of particles finer, lighter, and more transportable 
by water than the sea-sand. While, therefore, the billows 
raised by a heavy west wind may roll up and deposit along the 
beach thousands of tons of sand, the sane waves may swallow 
up even a larger quantity of fine shore-earth. This earth, with 
a portion of the sand, is swept off by northwardly and south- 
wardly currents, and let fall at other points of the coast, or 
earried off, altogether, out of the reach of causes which might 
bring it back to its former position. 
Although, then, the eastern shore of the German Ocean here 
and there advances into the sea, it in general retreats before it, 
and but for the protection afforded it by natural arrangements 
seconded by the art and industry of man, whole provinces 
would soon be engulfed by the waters. This protection con- 
sists in an almost unbroken chain of sand banks and dunes, ex- 
tending from the northernmost point of Jutland to the Elbe, a 
distance of not much less than three hundred miles, and from 
the Elbe again, though with more frequent and wider interrup- 
tions, to the Atlantic borders of France and Spain. So long 
as the dunes are maintained by nature or by human art, they 
serve, like any other embankment or dike, as a partial or a 
complete protection against the encroachments of the sea; and 
on the other hand, when their drifts are not checked by natural 
processes, or by the industry of man, they become a cause of as 
certain, if not of as sudden, destruction as the ocean itself 
whose advance they retard. On the whole, the dunes on the 
coast of the German Sea, notwithstanding the great quantity of 
often fertile land they cover, and the evils which result from 
their movement, are a protective and beneficial agent, and 
