SAND DUNES. 627 



in Schleswig. If, in any part of the protected zone, a shelving 

 cliff of sand unprotected by vegetation is exposed to the wind ; 

 it should be covered with branches of pine, gorse, broom, etc., 

 placed like slates on a roof, and some sand-fixing grass sown 

 to prevent the sand from being carried inland. 



b. Method of Formation. 



The inequalities of the ground should first be levelled in order 

 to afford the wind as few points of attack as possible. Sand- 

 fixing grasses should then be sown or planted, the former 

 method being followed in France and the latter in Germany. 

 Pieces of the grasses should be planted in rows at right angles 

 to the direction, of the prevalent wind, holes being made with 

 a spade 1 foot to 2 feet apart, and three or four pieces of rhizome 

 planted in each hole so deeply that only about 6 inches of them 

 appear above the sand. They soon sprout and send out suckers 

 in all directions through the sand, which they fix most 

 effectually. 



The cost of fixing sand with grass is that of 70 to 140 days' 

 work at 8s. a day, averaging 15 an acre. In Prussia, long- 

 rooted yearling pines are then planted 1 foot apart in rows 

 distant 3 feet from one another. The work is done with an 

 iron dibble, so as not to loosen the sand unnecessarily. Moun- 

 tain-pine is the best species in the north for fixing the sand, 

 other trees being eventually planted between the pines. 

 Cuttings of poplars or willows may be also planted. 



In fixing dunes along the Baltic coast, Prussia spent 3,100 

 a year between 1884 and 1887, during which time 230 acres 

 were fixed with grass and 608 acres stocked with trees. This 

 is now being continued at an' annual cost of 5,000. 



The planting is usually effected under the protection of the 

 littoral dune, and pine forests in the protective zone are then 

 managed under the Selection system, and broadleaved species 

 are coppiced. 



In the Danish island of Zealand, up to 1866, sowing was pre- 

 ferred to planting, the sand being previously covered with a 

 thin coating of loam which was placed on the ground in heaps 

 in the autumn, and somewhat weathered by the winter's frost 

 before being spread over the area in the spring. 



s s 2 



