FOSSILS, AND HOW THEY ARE FORMED 5 



of the human race, and been gazed upon by 

 her grandfather a thousand times removed. 

 The answer to this query is that, unless the con- 

 ditions were such as to preserve at least the 

 hard parts of any creatm'e from immediate de- 

 cay, there was small probabihty of its becom- 

 ing fossilized. These conditions are that the 

 objects must be protected from the air, and, 

 practically, the only way that this happens in 

 nature is by having them covered with water, 

 or at least buried in wet ground. 



If an animal dies on dry land, where its bones 

 lie exposed to the summer's sun and rain and 

 the winter's frost and snow, it does not take 

 these destructive agencies long to reduce the 

 bones to powder; in the rare event of a cli- 

 mate devoid of rain, mere changes of temper- 

 ature, by producing expansion and contraction, 

 will sooner or later cause a bone to crack and 

 crumble. 



Usually, too, the work of the elements is 

 aided by that of animals and plants. Every 

 one has seen a dog make way with a pretty 

 good-sized bone, and the Hyena has still greater 

 capabiUties in that line ; and ever since verte- 



