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FOSSILS, AND HOW THEY ARE FORMED 



"How of a thousand snakes each one 

 Was changed into a coil of stone." 



Fossils are the remains, or even the indications, of 

 animals and plants that have, through natural agencies, 

 been buried in the earth and preserved for long periods 

 of time. This may seem a rather meagre definition, but 

 it is a difficult matter to frame one that will be at once 

 brief, exact, and comprehensive; fossils are not neces- 

 sarily the remains of extinct animals or plants, neither 

 are they, of necessity, objects that have become petri- 

 fied or turned into stone. 



Bones of the Great Auk and Rytina, which are quite 

 extinct, would hardly be considered as fossils; while the 

 bones of many species of animals, still living, would 

 properly come in that category, having long ago been 

 buried by natural causes and often been changed into 

 stone. And yet it is not essential for a specimen to 

 have had its animal matter replaced by some mineral 

 in order that it may be classed as a fossil, for the 

 Siberian Mammoths, found entombed in ice, are 

 very properly spoken of as fossils, although the flesh 

 of at least one of these animals was so fresh that it was 

 eaten. Likewise the mammoth tusks brought to 

 market are termed fossil-ivory, although differing but 

 little from the tusks of modern elephants. 



Many fossils indeed merit their popular appellation 

 of petrifiactions, because they have been changed into 

 stone by the slow removal of the animal or vegetable 

 matter present and its replacement by some mineral, 

 usually silica or some form of lime. But it is necessary 

 to include ' indications of plants or animals' in the above 



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