FOSSILS, AND HOW THEY ARE FORMED 7 



ocean or one of its estuaries, settles to the 

 muddy bottom of a lake or is caught on the 

 sandy shoals of some river, the chances are 

 good that its bones will be preserved. They 

 are poorest in the ocean, for unless the body 

 drifts far out and settles down in quiet waters, 

 the waves pound the bones to pieces with stones 

 or scour them away with sand, while marine 

 worms may pierce them with burrows, or 

 echinoderms cut holes for their habitations ; 

 there are more enemies to a bone than one 

 might imagine. 



Suppose, however, that some animal has 

 sunk in the depths of a quiet lake, where the 

 wash of the waves upon the shore wears the 

 sand or rock into mud so fine that it floats out 

 into still water and settles there as gently as 

 dew upon the grass. Little by little the bones 

 are covered by a deposit that fills every groove 

 and pore, preserving the mark of every ridge 

 and furrow ; and while this may take long, it 

 is merely a matter of time and favorable cir- 

 cumstance to bury the bones as deeply as one 

 might wish. Scarce a reader of these lines but 

 at some time has cast anchor in some quiet 



