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8 Sci Earth's Past
8th Grade Science Clues to Earth's Past
Question | Answer |
---|---|
PALEONTOLOGIST | SCIENTISTS WHO STUDY FOSSILS |
FOSSIL | THE REMAINS, IMPRINTS, OR TRACES OF PREHISTORIC ORGANISMS PRESERVED IN ROCK. |
PERMINERALIZED | FOSSILS IN WHICH THE SPACES INSIDE ARE FILLED WITH MINERALS FROM GROUNDWATER. |
CARBONACEOUS FILM | A THIN FILM OF CARBON RESIDUE FORMING A SILHOUETTE OF THE ORIGINAL ORGANISM. |
MOLD | A FOSSIL FORMED AS A CAVITY IN A ROCK. |
CAST | A COPY OF THE ORIGINAL OBJECT FORMED WHEN SEDIMENTS FILL A MOLD AND HARDEN. |
TRACE FOSSILS | FOSSILIZED TRACKS AND OTHER EVIDENCE OF THE ACTIVITY OF ORGANISMS. |
INDEX FOSSILS | THE REMAINS OF SPECIES THAT EXISTED ON EARTH FOR RELATIVELY SHORT PERIODS OF TIME, USED BY SCIENTISTS TO DETERMINE THE AGE OF ROCK LAYERS. |
PRINCIPLE OF SUPERPOSITION | IN UNDISTURBED ROCK LAYERS, THE OLDEST ROCKS ARE ON THE BOTTOM AND THE YOUNGEST ROCKS ARE ON THE TOP. |
RELATIVE DATING | DETERMINES THE ORDER OF EVENTS AND RELATIVE AGE OF ROCKS BY EXAMINING THE POSITION OF ROCKS IN A SEQUENCE. |
UNCONFORMITIES | GAPS IN THE ROCK LAYERS DUE TO EROSION, NONDEPOSITION, OR BOTH |
ABSOLUTE DATING | USES THE PROPERTIES OF ATOMS IN ROCKS AND OTHER OBJECTS TO DETERMINE THEIR EXACT AGES. |
RADIOACTIVE DECAY | ELEMENT THAT GIVES OFF RADIATION DUE TO AN UNSTABLE NUCLEUS. |
HALF-LIFE | TIME IT TAKES FOR HALF THE ATOMS IN A RADIOACTIVE ISOTOPE TO DECAY. |
RADIOMETRIC DATING | DETERMINES THE ABSOLUTE AGES OF ROCKS BY MEASURING THE AMOUNTS OF PARENT AND DAUGHTER MATERIALS IN A ROCK AND BY KNOWING THE HALF-LIFE OF THE PARENT. |
UNIFORMITARIANISM | STATES THAT EARTH PROCESSES HAPPENING TODAY ARE SIMILAR TO THOSE THAT HAPPENED IN THE PAST. |
PETRIFIED | FOSSIL REMAINS THAT FORMED WHEN SOME OR ALL OF THE ORIGINAL ORGANISM IS REPLACED WITH MINERALS. |