contain evidence that Earth is very old
the geologic time scale was developed using
fossils and superposition
If Earth's history lasted only one year, humans would have appeared
process in which one element changes into another
states that older rock layers are generally under younger rocks
the longest units of geologic time
time it takes for half of a radio active element to break down into another elelment
preserved remains or evidence of ancient life-forms
stable substance formed from a radioactive one
a scale of Earth's natural history
geologic time scale
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