606 THE LANDES OF GASCONY. 
mere accidental fissure in the superficial stratum may soon be 
enlarged to a wide opening, that will let loose sand enough to 
overwhelm a province. 
The Landes of Gascony. 
The most remarkable sand plain of France lies at the south- 
western extremity of the empire, and is generally known as 
the Landes, or heaths, of Gascony. Clavé thus describes it: 
“ Composed of pure sand, resting on an impermeable stratum 
called alzos, the soil of the Landes was, for centuries, consid- 
ered incapable of cultivation.* Parched in summer, drowned 
in winter, it produced only ferns, rushes, and heath, and 
scarcely furnished pasturage for a few half-starved flocks. To 
crown its miseries, this plain was continually threatened by 
the encroachments of the dunes. Vast ridges of sand, thrown 
up by the waves, for a distance of more than fifty leagues along 
the coast, and continually renewed, were driven inland by the 
west wind, and, as they rolled over the plain, they buried the 
soil and the hamlets, overcame all resistance, and advanced 
with fearful regularity. The whole province seemed devoted 
to certain destruction, when Brémontier invented his method 
of fixing the dunes by plantations of the maritime pine.”+ 
Although the Landes had been almost abandoned for ages, 
they show numerous traces of ancient cultivation and pros- 
perity, and it is principally by means of the encroachments of 
the sands that they have become reduced to their present deso- 
late condition. The destruction of the coast towns and harbors, 
which furnished markets for the products of the plains, the 
damming up of the rivers, and the obstruction of the smaller 
channels of natural drainage by the advance of the dunes, 
* The alios, which from its color and consistence was supposed to be a 
ferruginous formation, appears from recent observations to contain little iron 
and to owe most of its peculiar properties to vegetable elements carried down 
into the soil by the percolation of rain-water. See Revue des Haux et Fortis 
for 1870, p. 301. 
+ tudes Forestiéres, p. 250. See, also, Rectus, La Terre, i., 105, 106. 
