GROWTH OF DUNES. 375 



tinually re-formed, at a greater distance from the 

 sea. As the sand is carried farther inland by this 

 process, it makes way for new supplies from tlie 

 inexhaustible stores of the ocean. 



These waves of sand, invading the land by the 

 impulse of tlie wind, have, like the sea-waves, an un- 

 equal motion, according to the configuration of the 

 ground. Everything must alike yield to their con- 

 stantly advancing forces : cultivated land, forests, 

 houses, villages, and towns disappear beneath them ; 

 even pools of water retire before them, as in Gascony, 

 where, under the influence of the dunes, numerous 

 saltwater pools are pushed farther inland, and their 

 level constantly raised. 



As the Mediterranean is almost tideless, the dunes 

 are formed there with much less facility than on the 

 oceanic coasts. On the latter examples may be cited 

 of villages being buried like caravans in the desert. 



At a spot near St. Pol-de-Leon, in Brittany, 

 where a village stood in 1666, a few sand-hillocks, 

 with a few chimneys and steeples to indicate the 

 original site of the village, alone remained fifty years 

 after : the dunes had advanced at the rate of about 

 580 yards every year. The dunes of Gascony, how- 

 ever, do not grow with this frightful rapidity, their 

 progress not exceeding some 25 yards annually. If 

 the progress should remain constant, at this rate they 



