EFFECTS OF WEATHER 



sea. These sand-hills creep farther inland, till their 

 progress is stopped by the fields or woods they encounter, 

 or till, by seeds finding a root, vegetation springs up on 

 them and they harden and consolidate under the influence 

 of their own vegetation and move inland no farther. But 

 in many parts of Western Europe and Eastern America 

 the dunes are marching inland at the rate of twenty feet 

 a year. Off the coast of Friesland and North Germany 

 the danger has grown so threatening that scientific 

 attention has been given to the problem ; and the 

 German scientific men have employed ingenious devices 

 of planting wind-stakes something like the wooden 

 breakwaters that are to be found along every seaside 

 beach, but arranged at different angles, of forcing the 

 sand-dune to heap itself up so as to form an obstruction 

 to further arrivals ; or of sowing those plants in the sand 

 that will bind its particles together, in order to preserve 

 the land from further invasion. 



What goes on along the coast finds a parallel in the 

 interior of continents where, as in Arizona, in America, 

 or by the desert of Gobi, in; Asia, or in the Karroo of 

 South Africa, or in Central Australia and Africa, there 

 is great dryness of climate and a continual disintegra- 

 tion of the surface rocks. Sometimes the dust or sand 

 remains and gradually consolidates or hardens. More 

 often it is only a temporary visitor. Wind and rain are 

 continually removing it, sometimes in vast quantities, 

 into the sea ; and in the course of time the most as- 

 tounding changes are wrought in the surface and appear- 

 ance of the land. The softer rocks are worn down ; the 



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