| A | B |
|---|
| geology | the study of rocks and rock formations |
| relative dating | a method of putting events in the order in which they happen |
| fossil | the remains or traces of a dead animal or plant that has been preserved for a long time |
| paleontologist | a scientist who studies and identifies fossils |
| superposition | the bottom layer of a rock formation is older that the layer on top |
| geologic time scale | a model of the Earth's history |
| absolute dating | a method of measuring the age of an object in years |
| radioactive decay | refers to how unstable atoms lose energy and matter over time |
| element | a substance composed of only one kind of atom |
| half-life | the amount of time it takes for half of the unstable atoms in a sample to decay |
