150 H. S. WILLIAMS — NOMEMCLATURE AND CLASSIFICATION 



in order that actual history and time relations in geologic history may be 

 studied with a greater precision and freed from that vague prejudgment 

 which naturally arises from confusing chronologic with physical and 

 spacial ideas. 



It may be mentioned further that in the discussion of fossils, faunas, 

 and faunules time relations must be considered, since heredity and evo- 

 lution are time questions ; but for such discussions the formations and 

 their exact position in a stratigraphic scale must be first established, 

 independently of the fossils they contain, before the historical relations 

 of the fossil faunas can be accurately discriminated. In the same way 

 that physical geography must stand on a basis of physical definition 

 entirely independent of political boundaries or political characters, so 

 mustformational geology derive its definitions, terminology, and classifi- 

 cation from the characters which are actually possessed by formations 

 and which can be examined, measured, and defined before the history 

 of the organisms preserved in them can be accurately determined and 

 before questions of the absolute time relations of geologic events can be 

 established on a firm basis of fact. 



