History of Life1 Crossword
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
                           
 
 
Down: 1) theory that explains slow movement of solid continental plates2) the length of time required for half of the radioactive atoms in a sample to decay3) a scientist who studies fossils4) a division of geologic time into which eras are sub-divided6) a major division of geologic time7) used to identify fossils of same age in different places8) a species who has died out and has no living members Across: 5) time line used to represent Earth's history9) used to determine whether a fossil is older or younger than another10) uses carbon-14 or Potassium-40 to find the absolute age
 

 

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