NAKEDNESS OF DUNES. 
485 
line since the formation of the oldest hillocks, and these have 
become inland dunes, while younger rows have been thrown 
up on the new beach laid bare by elevation of the sea bed. 
Our knowledge of the mode of their first accumulation is de¬ 
rived from observation of the action of wind and water in the 
few instances where, with or without the aid of man, new 
coast dunes have been accumulated, and of the influence of 
wind alone in elevating new sand heaps inland of the coast 
tier, when the outer rows are destroyed by the sea, as also 
when the sodded surface of ancient sands has been broken, and 
the subjacent strata laid open to the air. 
It is a question of much interest, in what degree the naked 
condition of most dunes is to be ascribed to the improvidence 
and indiscretion of man. There are, in Western France, ex¬ 
tensive ranges of dunes covered with ancient and dense forests, 
while the recently formed sand hills between them and the sea 
are bare of vegetation, and are rapidly advancing upon the 
wooded dunes, which they threaten to bury beneath their 
drifts. Between the old dunes and the new, there is no dis¬ 
coverable difference in material or in structure; but the modern 
sand hills are naked and shifting, the ancient, clothed with 
vegetation and fixed. It has been conjectured that artificial 
methods of confinement and plantation were employed by the 
primitive inhabitants of Gaul; and Laval, basing his calcula¬ 
tions on the rate of annual movement of the shifting dunes, 
assigns the fifth century of the Christian era as the period when 
these processes were abandoned.* 
There is no historical evidence that the Gauls were ac¬ 
quainted with artificial methods of fixing the sands of the 
coast, and we have little reason to suppose that they were ad¬ 
vanced enough in civilization to be likely to resort to such 
processes, especially at a period when land could have had but 
a moderate value. 
* Laval, Memoire sur tes Dunes de Gascogne, Annates des Fonts et 
Chaussees , 1847, 2me s6mestrc, p. 231. The same opinion had been ex¬ 
pressed by Be£montiek, Annates des Fonts et Chaussees , 1833, ler s^mestre, 
p. 185. 
