nyenye Flashcards
1
Q
million of years
A
age
2
Q
tens of millions of years
A
epoch
3
Q
one hundred million years
A
period
4
Q
half a billion of years or more
A
era
5
Q
the largest time span of the geologic time scale (one billion years or more)
A
eon
6
Q
- k-40 half-life 1.3 billion years
- decays into argon and calcium
- used to date rocks older than 100,000 years old
A
potassium-argon method
7
Q
- U-238 half life 4.5 billion years
- decays into lead-206
- used for rocks more than 10 million years old
A
uranium lead method
8
Q
- Rb-87 half life 49 billion years
- Decays into strontium-87
- used for rocks more than 10 million years old
A
rodinium strontium method
9
Q
organism that recently died
A
carbon 14 method
