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Uniformitarianism
The present is the key to the past.
Cross cutting relations
The fracture cutting the rocks is younger than the rocks being cut.
Superposition
False.
Primary rocks
Sedimentary rock whose clasts were weathered from igneous and metamorphic rock (Hutton).
Eons order
Hadean, Archean, Proterozoic, Phanerozoic.
Eon without evidence for life
Hadean.
Eons with evidence of microbial life alone
Archean, Proterozoic.
Youngest Eon with three eras
Phanerozoic.
Half-life of a radioactive element
False.
Number of half-lives elapsed
Three.
Age of the rock with a half-life of 20 million years
60 Ma.
Note 
Flashcard (65)