PAL^ONTOLOGICAL BOTANY. 



The study of the changes which have taken place in the 

 nature of living beings since their first appearance on the 

 globe till the period when the surface of the earth, having 

 assumed its present form, has been covered by the creation 

 which now occupies it, constitutes one of the most important 

 departments in Geology. It is, as Brongniart remarks, the 

 history of life and its metamorphoses. The researches of 

 geologists show clearly that the globe has undergone various 

 alterations since that "beginning" when "God created the 

 heavens and the earth." These alterations are exhibited in 

 the different stratified rocks which fomi the outer crust 

 of the earth, and which were chiefly sedimentary deposits 

 produced by the weathering of the exposed rocks. Re- 

 mains of the plants and animals living on the globe at 

 the time of the formation of the different beds are pre- 

 served in them. Elevations and depressions of the sur- 

 face of the earth affected the organisms on its surface, and 

 gave to successive deposits new faunas and floras. Some of 

 these epochs have been marked by great changes in the 

 physical state of our planet, and they have been accompanied 

 with equally great modifications in the nature of the living 

 beings which inhabited it. The study of the fossil remains of 

 animals is called Palseozoology (jTaXaio^, ancient, and ^SoVj 

 animal), while the consideration of those of vegetables is 

 denominated Pal^eophytology (TraXatos and (jyvrov, a plant). 

 Both are departments of the science of Palaeontology, which 



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