|
|
|
2
|
the number of protons and neutrons in the nucleus
|
|
4
|
the present is the key to the past
|
|
5
|
the number of protons and neutrons in the nucleus
|
|
6
|
an erosional surface in the rock record produced by erosion
|
|
8
|
charged particles
|
|
9
|
the time required for one-half of the radioactive nuclei to decay
|
|
10
|
layers
|
|
11
|
layers on each side of the unconformity are parallel
|
|
|
|
|
|
|
1
|
unstable radioactive isotope
|
|
2
|
tilted rocks are covered by flat-lying rocks
|
|
3
|
same atomic number different number of neutrons same element with a different mass number
|
|
7
|
makeup an eon
|
|
|
|
