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I AMERICAN FORESTRY I 



VOL. XXVI 



JANUARY 1920 



NO. 313 



THE FOREST POLICY OF FRANCE 



THE CONTROL OF SAND DUNES AND MOUNTAIN TORRENTS* 



BY W. B. GREELEY 



FORMERLY LIEUTENANT - COLONEL, 20TH ENGINEERS, A. E. F. 



TWO facts stand out in the physical history of France 

 which offer valuable lessons to the United States. 

 The first is the solidarity between the mountain 

 and the plain the direct effect upon the lowlands of 

 upsetting the normal balance of soil and vegetation in 

 the uplands. The second 

 is the value of the forest 

 in stopping the movements 

 of soil and water which 

 have wrought havoc, in 

 varying degrees, in practi- 

 cally every country on the 

 earth. These lessons have 

 been brought home to the 

 French with force in the 

 valleys watered by the Alps 

 and the Pyrenees, and their 

 long battles with torrential 

 floods in the one instance, 

 and with invading sand 

 dunes in the other, have 

 influenced profoundly their 

 public forest policy. 



The receding waters of 

 the Bay of Biscay left a 

 vast level stretch of sand 

 and marsh in southwestern 

 France known as the 

 "Landes." Toward the sea, 

 these barrens terminate in 

 a belt of dunes from 6 to 

 10 miles in width. The 

 dunes have doubtless moved 

 inland at various periods, 

 but appear to have been 

 relatively stable during the 

 Middle Ages. In the 

 Seventeenth and Eighteenth Centuries, a new and menac- 

 ing invasion of the interior took place, which French 

 geologists attribute, in part at least, to the upsetting of 

 the equilibrium of things by human action. The vege- 



IN THE FRENCH ALPS 



All this section is denuded but efforts to prevent further washing away 

 of the soil are being made by the erection of a large number of 

 gully dams, some of which can be seen in the foreground. 



* Material for this article has been taken largely from "Cours de 

 Droit Foresteir" by Charles Gugot, and from data prepared by G. Garbe, 

 Engineer des Ponts et Chansses. 



tative cover which had formed on the dunes themselves 

 appears to have been broken up by the heavy grazing 

 of the Gascon herds. At the same time, the increasing 

 population in the Pyrenees, supported largely by pastoral 

 industries, led to the progressive denudation of their 



steep mountain slopes, fill- 

 ing the rivers with detritus 

 and swelling the dune 

 forming materials available 

 to the tides and winds. At 

 all events, the dunes on the 

 coast of Gascony became 

 dangerously active, many 

 of them moving inland 

 from 30 to 90 feet a year 

 and burying farms and 

 villages in their path. 



Various attempts to 

 check this invasion were 

 made during the Eighteen- 

 th Century; but Bremon- 

 tier, an Engineer of "Ponts 

 et Chausses," is credited 

 with having developed the 

 methods which were suc- 

 cessful in halting the de- 

 structive course of the 

 dunes. Bremontier's 

 scheme, which was worked 

 out about 1784, comprised 

 three steps : 



(1) The construction of 

 a rampart along the coast, 

 a sort of sea-wall against 

 incoming waves of sand. 

 This was done usually by 

 piling quantities of brush 

 upon the last dune which was forming on the beach and 

 building up this brush revetment, layer by layer, as fast 

 as it filled with sand, until the sand could no longer 

 break over the top. 



(2) Planting hardy herbs on the dunes within the 

 rampart until their surface became stable. 



