1. The geologic time scale is a system of chronological dating that relates geological strata to time, used by geologists, paleontologists, and other Earth scientists to describe the timing and relationships of events in Earth's history.
2. The largest unit of geologic time is an eon.
3. The three major divisions of geologic time are eons, eras, and periods.
4. The most recent division of geologic time is the Cenozoic Era.
5. Finding fossils in different rock layers helps scientists determine the relative ages of rocks and the organisms that lived during those times, allowing them to correlate rock layers across different locations and reconstruct past environments and evolutionary sequences.
6. There are 4 main eras of geologic time: Precambrian, Paleozoic, Mesozoic, and Cenozoic.
7. Scientists use radiometric dating, fossil correlation, and stratigraphic principles to develop the geologic time scale.
Build Challenge
| Organism | Eon | Era | Period | Precedence |
|-----------------|---------------|--------------|--------------|------------|
| Humans | Phanerozoic | Cenozoic | Quaternary | 10 |
| Dinosaurs | Phanerozoic | Mesozoic | Cretaceous | 8 |
| Trilobites | Phanerozoic | Paleozoic | Cambrian | 2 |
| Fish | Phanerozoic | Paleozoic | Ordovician | 3 |
| Reptiles | Phanerozoic | Mesozoic | Triassic | 7 |
| Amphibians | Phanerozoic | Paleozoic | Devonian | 5 |
| Mammals | Phanerozoic | Cenozoic | Paleocene | 9 |
| Flowering Plants| Phanerozoic | Cenozoic | Cretaceous | 6 |
| Birds | Phanerozoic | Mesozoic | Jurassic | 4 |
| Insects | Phanerozoic | Paleozoic | Carboniferous| 1 |
Parent Tip: Review the logic above to help your child master the concept of geologic time scale worksheet.
