| A | B |
|---|
| How old is the earth? | 4.6 billion years old |
| The name of the time from the earth's formation to the beginning of the Paleozoic? | Precambrian time |
| Age of Reptiles; First birds; Dinos dominated | Mesozoic Era |
| Age of Mammals; shortest of the 3 eras | Cenozoic Era |
| Means "ancient life"; simpler life forms such as amphibians and fish | Paleozoic Era |
| Any method of measuring the age of an event or object in years | absolute dating |
| The process of unstable nuclei breaking apart | radioactive decay |
| Name of 3 eras in the Phanerozoic Eon | Paleozoic, Mesozoic, Cenozoic |
| Why can't geologists use absolute dating on sedimentary rock? | Sediments are from many types of rocks of different ages |
| A method of determining the age of an object by estimating the relative percentages of radioactive vs stable atoms | Radiometric dating |
| Ratio of unstable to stable atoms in very old rocks | the older it is, the more stable daughter product it has |
