| A | B |
|---|
| geology | the study of the Earth |
| geologic time scale | an outline of Earths history |
| era | the largest division of geologic time |
| big bang theory | suggests that all matter (anything that has weight and takes up space) and space were once concentrated in a single great dense glowing mass. The mass exploded into billions of galaxies that are moving away from each other. |
| theory | ideas supported by a lot of evidence |
| law | a theory that has been proven again and again |
| pangaea | all the continents on Earth were once one giant land mass. Pangaea is the name given to this land mass. It broke apart in the Mesozoic era. |
| index fossils | fossils that mark a certain time in Earths history |
| fossils | impressions of organisms that have been pictured in stone |
| trilobite | an index fossil from the Paleozoic time period |
| ammonite | index fossil from the Mesozoic time period |
| extinct | the term used when a specie has totally died out |
| relative dating | a date that is close to exact |
| radiometric dating | a technique that uses radioactivity to find the approximate age of certain rocks |
| half-life | the amount of time needed for 1/2 of the radioactive atoms to break down |
