A FOREST TOUR AMON: THE DUNES OF GASCONY. 297 
reverse side of the second wattle. In the centre of the mound, a 
palisade of planks, also 40 in. above and 20 in. below ground, is 
erected—the planks, which are of pine sapwood, 7 in. or 8 in. wide, 
and 1+ in. thick, being placed #ths of an inch apart. When the 
sand drifts up against them, a portion of it falls through the inter- 
vals, thus affording support on the other side ; and when they have 
become nearly covered, they are raised about 2 ft. out of the ground 
by means of a hand-lever and chains. This operation, which we 
saw done, is repeated from time to time, until the barrier has 
attained a height of about 25 feet, when a third wattle fence is con- 
structed, at a distance of from 5 to 6} ft. behind the inner slope ; 
and the top of the barrier is strengthened by means of a line of 
small fagots formed of pine branches, gorse, and other shrubs, which 
are half-buried vertically in the sand. The fagots, each of which 
weighs about 45 lbs., are placed at distances of 4} feet from centre 
to centre. During the time that elapses before the last fence is 
overtopped, the palisade is not raised, so that the width of the base 
is increased, and the top becomes broader and rounded. When the 
palisade, which is now moved back a short distance, is overtopped, 
it is raised as before, an additional wattle being placed in rear of 
the work ; and the building up of the mound by the action of the 
wind is continued in this manner, until it has attained its maximum 
height of from 40 to 45 ft., when its breadth is allowed to increase, 
until it stands on a base about 330 ft. broad. The foot of the 
outer slope is then about 100 ft. distant from high-water mark, the 
top being at least 165 ft. broad, and the slopes standing at 35 or 
40 degrees. This result is usually attained in from 15 to 18 
years, but the rate of the barrier’s growth is by no means regular. 
Strong and steady west winds are the most favourable; but when 
the sand is raised by squalls, it is sometimes carried inland in con- 
siderable quantities. The artificial dune must be broad at the top, 
and its profile must be such that the most violent storms do not 
easily “take hold” of it; but if these conditions are fulfilled, its 
maintenance is easy and cheap; and if the base of the outer slope 
be kept at the prescribed distance from high-water mark, the sea, 
even if it reaches it during exceptionally bad weather, does the 
structure but little damage. 
The surface of the mound is consolidated by fagots, 12 to 14 
in, in circumference.and 14 to 16 in. apart, buried vertically to a 
depth of 16 in. in the sand, and projecting 8 to 16 in. above 
ground. It is also sown with gowrbet (Arundo arenaria), about 
