64 



THE OPAL SEA 



Muddy 

 bottoms and 

 their effects. 



Mineral 

 stains. 



Sea saw- 

 dust. 



at times so turbid that a few feet may obscure 

 all vision ; the Yellow Sea is yellow largely be- 

 cause of its muds held in solution ; and in other 

 seas and bays vegetable deposits produce differ- 

 ent hues of red, bro^Ti, or gray. There is little 

 doubt also that minerals may make local colors 

 in the sea as in the smaller fresh-water pools 

 of the land. The stain of iron has given the 

 water along many a rocky shore a saffron hue, 

 and the small streaks of bright blue-green that 

 occasionally show in shallow bays may possibly 

 be caused by some vein of copper underlying 

 them. 



Aside from such local happenings, aside 

 from patches of " sea sawdust " (beds of float- 

 ing cylinder-shaped algcB of minute propor- 

 tions, or swarms of one-celled animalculae that 

 give the sea distinct hues of red, brown, or 

 white), there are heights and depths of sea 

 color that extend in body over vast areas. The 

 sea is not an unbroken blue. That there is 

 variety no one can doubt who has seen the Gulf 

 Stream flowing in a dark current through the 

 lighter colored body of the Atlantic. The con- 

 trast is too apparent. The ultramarine cur- 

 rent changes under different skies; but no 

 matter what the sky, the Gulf Stream is al- 

 ways a darker and a different hue from its 



