ON THE SEA COAST. 231 



to hurry is avoided in raising the height of the littoral dune, other- 

 wise its height may become too great for its base with the result 

 that its stability would be seriously impaired. To give greater 

 stability to the littoral dune a tight-bound fence about 5 feet high 

 is erected behind the paling. The wattling is at first carried up 

 to not more than a yard from the ground ; but as the dune rises, 

 it is continued upwards. Since the fence cannot be raised like the 

 paling, a new one has to be erected as soon as the preceding one 

 has been covered by the sand. If, notwithstanding these precau- 

 tions, the wind is apt to breach the dune, other rows of palings, 

 making a certain angle with the first, are erected on the steep face 

 behind, in order to widen the dune or to form buttresses. 



When the littoral dune has attained a sufficient height, the for- 

 mation of a new one may be commenced nearer the sea. In any 

 case the constant maintenance of a littoral dune is an absolute 

 necessity ; otherwise every benefit resulting from previous opera- 

 tions must inevitably be lost by the continual drifting in of new 

 sand. 



Behind the protection afforded by the littoral dune, the interior 

 dunes are fixed by the planting or sowing of grasses and species of 

 Carex and other plants growing up rapidly and extending them- 

 selves by means of rhizomes, suckers or creeping Footing-stems, 

 The plants are put down or made to come up in tufts, or, better 

 still, continuous lines, which may consist of two parallel series run- 

 ning at right angles to one another. 



Before the seeds are sown or the plants put down, all the stepper 

 slopes on the windward side should be cut down and given a gentle 

 ramp so as to offer as little resisting surface to the wind as possi- 

 ble. The valleys and deeper depressions may also be filled to a 

 less or greater extent by erecting hurdles or fences across them, 

 to arrest the sand drifting in their direction. 



Until the sowings or transplants are advanced enough to have 

 taken a firm hold of the soil it may be found necessary to protect 

 them against subsequent drifting of the sand. This may be done 

 in several ways as follows : 



I. By means of branches containing numerous twigs. These 

 branches are laid end to end over the ground in continuous lines 

 touching one another, and in such a manner that the top of one 

 branch is in contact with or covers the cut extremity of the next. 

 Long poles are then placed across the branches from 4 to 6 feet 

 apart and made fast to the ground by means of wooden hooks 

 driven into the sand. It is always advisable to lay the branches 



