| A | B |
|---|
| ripple marks | small waves on surface of sand caused by water or wind |
| law of crosscutting relationships | a fault or intrusion is younger than a rock layer it cuts across |
| absolute age | numeric age |
| varve | band of sand deposited each year |
| radiometric dating | using radioactive decay to determine absolute age |
| radioactive isotope | nuclei that emit particles at constant rate |
| parent isotope | original radioactive isotope |
| daughter isotope | newly formed isotope |
