156 



THE OPAL SEA 



Drift of 

 sands. 



Saitd dunes. 



on the shore, above the tide line, over the 

 shells, over the kelp, over the vanishing wrecks 

 of ships. 



In a few days perhaps these tons and tons 

 of newly-arrived sands have dried out in the 

 sun, and when the cool sea breezes blow inland 

 to take the j^lace of the vacuum left by the 

 rising heated air of the coast, the sands begin 

 to move. Backward from the sea they drive and 

 drift; but they do not go far before meeting 

 with obstructions. It may be only a piece of 

 timber or a clump of bushes ; but in either case 

 when once a pause is made, once an obstacle 

 bars the way, the sand bank begins to grow like 

 the snow bank. The sand drifts up and over, 

 dropping at the back, so that there is a con- 

 tinual accumulation in the rear; while grasses 

 seem to spring up and pin down what is already 

 gathered. And so perhaps, after many years, 

 there is a row of sand hills or dunes stretch- 

 ing along the beach, thinly covered with a 

 long, wiry grass that holds them in shape like 

 a net. 



The dunes are barriers against the sea aud 

 very effective ones at that. As sand they are 

 more indestructible than they ever were as rock. 

 The hard surviving kernels of the stone they 

 are usually of uniform size and pack together 



