RECLAMATION OF THE SOIL. 



]43 



together, and it is said that the young pines grow all the 

 better when surrounded by the two other species. 



The cost of these operations is considerable, amounting 

 sometimes to ten pounds per acre and more ; the expenditure 

 will not be found excessive, if it is remembered that fertile 

 lands beyond the dunes may thus be protected against being 

 covered by sand. 



I). Inland Dunei<. 



These are treated in a manner similar to that described in 

 the case of coast dunes, with this exception, that the con- 

 struction of a forward dune, 

 corresponding to the littoral 

 dune on a sea shore, may not 

 be necessary. In many cases 

 it may suffice to arrest the for- 

 ward movement of the sand 

 on the windward side by a 

 wattle fence until the ground 

 has been covered with a growth 

 of trees, shrubs and grasses. The temporary fixation of the 

 sand is here frequently effected by means of pieces of turf, 

 which are laid in rows or squares, within which the sowing 

 or planting is done (Fig. 21). 



In the case of both coast and inland dunes it is essential 

 to keep all domestic animals out of the area, at any rate 

 for a number of years after it has been fixed, as they disturb 

 the sand. When the area has been stocked with ti-ees, clear 

 cuttings must be strictly avoided, the wood being treated 

 under the selection system, else the work may have to be 

 done over again.* 



6. Fixation of Unstable Soil on Slopes. 

 Owing to the action of water, soil on sloping ground may 

 become unstable. Water filtering downwards causes a re- 

 duction in the cohesion of the different layers of the soil, 



* For further details see Volume IV. of this Manual. 



