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Topic 6

by McKenna Lee    
Horizontales
Ex: platypus or bird
A time scale that uses rocks to tell us about history
Ex: whale or human
Hundreds of millions of years
Ex: layers of rock found in mountains
What happened to dinosaurs
Ex: lizard or snake
An estimated age
Verticales
calculating the age of rocks and minerals by measuring the presence of some radioactive elements
Ex: frog or salamander
An exact age
Ex: worm or jelly fish
Process by which an unstable nucleus looses energy by radiation
Shells or bones preserved in rock
Began 2.4 million years ago