EARTH'S UNDERGROUND STOREHOUSE 197 



Then the waters of the brooks carry the gold and 

 the bits of quartz sand as far as they can, and drop 

 them, nicely sorted in layers according to their 

 weight. 



Do you remember that the brooks dropped their 

 heaviest burdens in their own channels, and carried 

 the lighter particles along, spreading some of them 

 out in the low place, taking others on to the ocean? 

 Where, then, should you think that the brooks would 

 drop the gold? The pieces of gold were smaller than 

 much of the sand and gravel, but were they heavier 

 or lighter? 



Gold is hesivy. It is one of the heaviest of metals 

 — even heavier than lead or iron — heavier, too, 

 than the grains of quartz sand or the pebbles in the 

 gravel. So it would be dropped in the bed of the 

 stream with the heavier pieces of quartz and rock, 

 while the sand was carried along toward the sea. 

 There the gold would lie, not packed close and snug 

 in a soHd mass as it was for so long in the fissure of 

 the rock, but lying loose in tiny flakes or larger grains 

 and nuggets. It had become a free thing. Each par- 

 ticle, large or small, was an individual, and could 

 move when the water rolled it along or when the 

 pebbles and sand pushed against it. 



The gold was ready now for men to use, but for a 

 long, long time they did not find it. Finally some one 

 who had sharper eyes than the rest noticed the pretty 

 golden specks in the bed of a stream, just as some one 

 saw the blackberry bush, and knew that the berries 

 were better because the bush grew in better soil. 

 When the gold had been discovered, men learned 



