Earth History

5. A fossil that forms when an organism is trapped buried in a way that prevents decay
6. The idea that Earth's features formed quickly due to sudden, violent events
7. The era following the Mesozoic, known as the 'Age of Mammals'
9. The scientific principle that the same natural processes occurring today have always happened
11. A fossil that forms when minerals fill a mold, creating a copy of the original organism
12. The principle that states older rock layers are found beneath younger ones
14. The method of dating that determines the actual age of a fossil in years
15. The dating method that measures radioactive decay to determine a fossil's age
16. The fossil record is divided into time periods, including this one known for the rise of dinosaurs
17. The fossilized imprint of an organism's movement, such as a footprint

1. The process of determining the relative order of past events without knowing their exact age
2. A fossil used to determine the age of rock layers because it was widespread and only existed for a short time
3. A fossil that forms when minerals replace the original material of an organism
4. The radioactive isotope used to date fossils up to about 50,000 years old
8. oldest era in Earth's history, before most complex life evolved
10. A fossil that forms when an organism decomposes, leaving an empty space in the shape of the organism
13. The era that came before the Mesozoic, known for early marine life and trilobites