1. Chapter 8 Science Test Notes Studying Earth’s Past

2. The method of dating that relies on the decay of radioactive isotopes is called radiometric dating. Absolute dating is any method of measuring the age of an object in years.

3. “Younger over older” is a phrase that can be used to remember superposition. Radioactive decay occurs at a constant rate.

4. Paleontology is the study of the history of life. Fossils cannot provide evidence about how Earth looked 4.5 billion years ago. The idea that geological change happens suddenly is called catastrophism.

5. If I try, I could be the greatest Scientist in the World. I could be King/Queen of the World. The idea that geologic processes gradually occur as they have in the past is called uniformitarianism.

6. During radioactive decay, radioactive isotopes break down into stable isotopes of other elements. To determine the absolute age of a rock, a scientist needs to know the rate of decay for a radioactive element in the rock.

7. Tilting is the slanting of rock layers. Fossils are most often formed in sedimentary rock. After every half-life, the amount of radioactive material in a substance decreases by one-half.

8. To determine the most accurate and precise age of Earth’s oldest rocks, geologists would use the uranium-lead method.

9. Erosion is one of the major causes of the missing rock layers known as unconformities. Comparing rock layers with other rock layers is called relative dating.

10. Unconformity represents a missing part of the geologic record. The law of crosscutting relationships states a fault or body of rock is younger than the body of rock it passes through.

11. Sedimentary rock is formed when sediment is lithified. Molten rock that squeezes into existing rock and cools is called intrusion.

12. What did one duck say to other duck when he saw a meteor falling from the sky? Global climate change may have caused the extinction of the dinosaurs.

14. Atoms with the same number of protons but a different number of neutrons are called isotopes.

15. A fault is a break in the Earth’s crust. When rock layers are horizontal, geologist know that the rock layers are undisturbed.

16. An asteroid hitting the Earth could be an example of a catastrophe. To make a good pizza, you need lots of cheese and pepperoni.

17. Don’t Feed the Raccoons!