| A | B |
|---|
| STRATUM | A LAYER OF THE EARTH CRUST. |
| FOSSIL | remains of a once-living thing. |
| geologic time chart | an outline of the history of the earth. |
| trilobite | MARINE ANIMAL THAT WAS NUMEROUSM DURING THE CAMBRAIN PERIOD OF EARTH HISTORY. |
| PETRIFICATION | THE REPLACEMENT OF LIVING PLANT MATERIALS OF MINERALS BY MINERALS. |
| SEDIMENTARY ROCK | ROCK THAT IS MADE UP OF SEDIMENTARY LAID DOWN IN LAYERS. |
| CORE | A SAMPLE OF THE EARTHS CRUST. |
| PAEONTOLOGISTS | THEIR JOB IS TO DISCOVER AS MUCH AS THEY CAN ABOUT PLANTS AND ANIMALS HAT NOLONGER EXISTS. |
