| A | B |
|---|
| fossil | preserved remains or trace of an organism that lived in the past |
| mold fossil | an organism buried in layers of rock decays leaving a cavity in its shape |
| cast fossil | a mold is filled with sand or mud in the shape of the organism |
| petrified fossil | minerals soak into the remains of an organism turning them to rock |
| preserved fossil | insect trapped in amber |
| trace fossil | footprint, burrow, trail |
| index fossil | used to determine age of rock layers |
| fossil record | gives important information about past life and environments on earth |
| law of superposition | each rock layer is older than the ones above it |
| relative age | age of one object compared to another object |
| trilobite | an example of an index fossil |
| igneous intrusion | magma that has cut through sedimentary rock layers |
| paleontologist | scientist who studies fossils |
| marine | having to do with the ocean |
