212 



THE OCEAN 



which formerly were a part of the sea, and wlilch have transformed 

 tliemselves by degrees into pools of saltish and finally fresh water. 

 In Sable Island, situated not far from the mouth of the St Law- 



Fig. 90.— Sable Island. 



rence, we can observe this phenomenon of transition actually in pro- 

 gress. While the large lagune of the interior, too extensive to be 

 rapidly purified, is still filled with salt water, the small ponds lying 

 between the dunes ai e already fresh water. 



Numerous have been the disasters occasioned by the invasion of 

 dunes or ponds during the historic era. The villages situated at the 

 eastern base of the dunes of Gascony, on the shores of the ponds, 

 must be moved from time to time towards the east, for fear that they 

 should be swallowed by the sands or the waters. At the approach of 

 the danger the threatened inhabitants sometimes attempted a vain 

 resistance. As soon as an east wind succeeded to the regular winds 

 from the west, herdsmen and labourers, armed with spades and pick- 

 axes, repaired in all haste to the top of the* dunes, and, filled with a 

 purposeless ardour, they destroyed the crest of sand, and delivered it 

 to the power of the wind. But the regular winds soon brought back 

 the sand again, the dunes recommenced their advance, and routed the 

 army of peasants. For fear of being buried they were obliged to 

 destroy their huts, in order to carry awnj^ the materials and build 

 new dwellings at a certain distance inland. Years and centuries 



