Geologic History Flashcards
1
Q
half life
A
amount of time required for 1/2 of a radioactive isotope to decay into a stable isotope
2
Q
radioactive % is never
A
0%
3
Q
law of superposition
A
in undisturbed sedimentary layers oldest on the bottom –> youngest on top
4
Q
Index fossils
A
lived for a (geological) short time (in 1 layer) over a large area
5
Q
How do you tell if its an intrusion or extrusion
A
contact metamorphism
6
Q
unconformity
A
buried erosion surface or GAP in rock record
