Geologic Time Scale

5. ending with the asteroid impact that wiped out the non-avian dinosaurs.
6. early humans that lived roughly 2.4 to 1.4 million years ago.
8. this is often called the "Age of Reptiles," with the rise and dominance of dinosaurs
10. the time of swampy forests. The decay of these plants created the massive coal deposits we mine today.
12. A subdivision of an era
13. A supercontinent that incorporated almost all of Earth's landmasses
14. It began roughly 11,700 years ago after the last major ice age
15. called the "Ice Age," this epoch lasted from 2.58 million to 11,700 years ago
17. The current geologic period, characterized by cyclic ice ages and the evolution of modern humans

1. it was a warm, wet time when giant dinosaurs like Brachiosaurus thrived and the first birds appeared
2. The current eon, which began 541 million years ago. It is defined by the abundance of complex, "visible" life
3. these represent shorter blocks of time, often used to describe the most recent 66 million years
4. Modern humans. Our species emerged roughly 300,000 years ago in Africa
7. The largest formal unit of geologic time
9. 66 million years ago after the extinction of the dinosaurs. It is known as the "Age of Mammals."
11. The first 600 million years of Earth's existence with extreme heat
12. the most severe mass extinction event in Earth's history.
16. A major division of time within an eon