167 
(a) Cutting off the further supply of sand from the ocean. 
To do this, what is called the " dune littorale " is formed. The old official system 
of constructing the protecting dune may briefly be described as follows : 
At a distance of from 150 to 200 yards from high-water mark, a wattle fence,* some 40 inches in 
height, is erected, parallel to the general coast line, and at right angles to the direction of the prevailing 
wind. The drifting sand is arrested by this fence, and mounting up to windward forms a gradual slope 
towards the sea. After sqme little time, this fence is overtopped, and a second is put some 6J feet from the 
base of the steep leeward slope formed partly by the sand which has been forced through the interstices 
of the first fence, and partly by the sand which has blown over the top. and parallel to the first fence. 
The space between these two fences is soon filled up, and the embryo dune assumes a certain profile. Midway 
between the two fences a palisade is erected. This palisade is formed of pine planks sharpened at one end, 
5 feet long, 7 inches to 8 inches wide, and 1J inches thick. The planks are driven into the ground some 
20 inches, and f of an inch apart, their breadth being at right angles to the direction of the wind. As the 
sand drifts up the windward or west slope of the dune, it is again arrested by the palisade, though part of 
if filters through the interstices between the planks, and forms a steep slope to the leeward, which serves as 
a support to the planks. The sand now gradually mounts up, and when nearly flush with the top of the 
palisade, the latter is levered up some 24 inches. This process is continued until the dune is some 25 to 30 
feet high, when a cordon of faggots is planted on the summit of the dune just to windward of the palisade. 
The palisade is now left in this last position until a third fence, which has been erected some 5 or 6 feet to 
the east of the leeward slope, is overtopped, and the base of the dune is increased without affecting the 
height by the sand blowing over the tops of the palisade and cordon. When this fence is covered, the palisade 
is moved back a few feet, and the sand coming over the tops of the cordon faggots fills in the space between 
them and the palisade. The latter is then again levered up, and the process continued until the dune 
assumes the final profile required. The formation of the artificial dune usually requires a period of from 
fifteen to eighteen years. The growth is naturally irregular, being dependent on the season. Steady, 
strong winds are the most favourable. On the completion of the dune the surface is consolidated by half 
burying, in a vertical position, faggots composed usually of pine branches. These faggots have usually a 
circumference of some 14 to 16 inches and a length of 30 inches, and are planted some 14 to 16 inches apart. 
Between thepe faggots is sown the seed of the " Gourbet" or " Marram Grass " (Ammophila arundinacea, 
Host.f), in quantity about 13 Ib. to the acre. The consolidation is naturally only requisite on the summit 
and windward slope J. 
M. Bagneris, Inspecteur de Forets, states : 
The sand-dunes at Gironde, in France, are sometimes 230 feet in height, but at Port Elizabeth the 
greatest height of any sand ridge yet fixed is 46 feet 6 inches, while many of them do not exceed 20 feet in 
height ; and although their appearance is arid and desolate in the extreme, they are by no means devoid of 
moisture. In ordinary weather the sand is moist even 1 inch or 2 inches below the summits of the ridges, 
and water is found anywhere a few feet below the limestone crust, in some places at 1 foot from the surface. 
Numerous wells, 4 feet to 12 feet in depth, have been sunk for supplying the men and animals on the work. 
Laurent|| mentions that the dunes in Algeria are so abundantly supplied that wells sunk to a depth of 10 feet 
or 12 feet contain water. Water is also found in the sands of Namaqualand. Its presence in the sand 
is generally attributed to capillary attraction. 
Schlich^f describes a somewhat simpler method of constructing the dune littorale : 
Although air currents are capable of moving the sand along level and gently sloping ground, they 
cannot lift it above a certain height. Hence it is necessary, at a moderate distance (100-300 feet) from high- 
water level, to form an artificial hill, which is high enough to arrest the forward movement of the sand, 
and this is done by the construction of an artificial dune, generally called the " littoral dune." With this 
* Tea-tree (Lcptosperinitm, &c.) would be used in coastal New South Wales, 
t Psamitia fircnaria. See Maiden in Agric. Gazette, Jan., 1895. 
j McNaughton, O.B., "The sand-dunes of Gascony." Agricultural Journal (Cape Town), 7th February, 1895. A 
valuable and exhaustive pa|x>r. 
Bagneris, " Manuol de Sylviculture." 
|| Laurent, " Memoire sur le Sahara." 
^[ Manual of Forestry, Vol. ii, p. 34. See also iv, 624, 
