1. Fossil Dating

2. HOW DO WE KNOW THE AGE OF FOSSILS? -Scientists use 2 methods to determine the age of fossils: 1. Relative Dating 2. Absolute Dating

3. Relative Dating Shows the order in which fossils occurred- does not give exact ages. Shows what organisms lived together. Scientists look at where fossils are located within the rock column. Use the Law of Superposition

4. Law of Superposition Sedimentary layers are deposited in a time sequence Oldest rock on the bottom, youngest at the top Youngest Oldest

5. Absolute Dating Determines the specific age of a fossil Looks at chemical properties 2 types: ◦ Carbon-14 (radiocarbon) ◦ Potassium-Argon

6. Carbon-14 Dating Also known as Radiocarbon dating Used to date organic substances Scientists measure the radiocarbon in the fossil to determine its age Can only date specimens up to about 60,000 years old

7. Potassium-Argon Dating Scientists determine the age of the rock surrounding the fossil to determine the fossil’s age. Used only for inorganic substances (rocks and minerals) Scientists measure the amount of argon in the rock to determine its age Dates rock 60,000 years old and older

8. QUIZ

9. Which rock layer is the oldest? Youngest? Oldest Youngest

10. If you wanted to figure out the exact age of a rock, what technique would you use? a.Relative Dating b.Carbon-14 Dating c.Law of Superposition d.Potassium-Argon Dating

11. If you were looking to find the exact age of a fossil that is at least 1 million years old, what technique would you use? a. Carbon-14 Dating b. Potassium-Argon Dating c. Relative Dating d. You can’t; it is impossible

12. If you wanted to figure out the exact age of a fossil that is less than 40,000 years old, what technique would you use? a. Carbon-14 Dating b. Potassium-Argon Dating c. Relative Dating d. You can’t; it is impossible