| A | B |
|---|
| Radiometric Dating | a technique that uses radioactivity to find the approxamit age of certain rocks |
| Radioactive Element | an element who's atoms change naturally to form new atoms |
| half life | the amount of time needed for 1/2 of the radioactive atoms to break down. |
| ammonite | an example of an index fossil from the Mesoic Era |
| trilobite | an example of an index fossil from the Paleozoic Era |
| law | a theory that has been proven |
| Big Bang Theory | suggests that all matter and space were all concentrated in a single dense glowing mass that exploded into all of the galaxies |
| theory | an idea based on facts that has not been proven |
| Era | a long division of time often ended by a change in climate or a "big event" |
| Geology | the history and the study of Earth |
| Fossil | a record of past life in the form of a track, trace, imprint, or remains found in rock |
| Relative dating | how old something is compared to others(this is older than that but younger than this) |
| extinct | died-off; no longer existing;no longer alive,no more of its type alive |
| Pangea | when all of the continents were once a giant land mass |
| index fossil | a fossil that can tell info about the rock layer in which it was found, such as age |
