This document discusses methods for determining the absolute age of rocks and objects. It explains that absolute age refers to the actual number of years something has existed. Radiometric dating is described as a technique that analyzes radioactive decay to estimate age by looking at how much decay has occurred in an object over time. Examples are given of using the decay of uranium to lead and carbon to nitrogen to date materials.

1. Absolute Age
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2. Absolute Age
• Absolute Age—the number age of a rock or an object
Example—Mr. Choi is 14 years old.

3. Estimating how much time has passed
• Let’s say this timer on the
left takes 1 minute for all
the sand to drop down to the
bottom.
If half the sand has fallen
through, how much time has
passed?

4. Estimating how much time has passed
• Let’s say this timer on the
left takes 10 minute for all
the sand to drop down to the
bottom.
If half the sand has fallen
through, how much time has
passed?

5. Estimating how much time has passed
• Let’s say this timer on the
left takes 4 minute for all
the sand to drop down to the
bottom.
If ¾ (3 quarters) the sand
has fallen through, how much
time has passed?

6. Estimating Earth’s age and other fossils
• Just like a glass timer, certain things on
Earth have a “timer” in them that tells
us how much time has passed.
This has helped us determine the age of
the Earth and other fossils.

7. Absolute Age
• Radioactive Decay—the process where an unstable
element becomes stable
Example: Radioactive Uranium  Stable Lead
Radioactive Carbon  Stable Nitrogen

8. Absolute Age
• Radiometric dating—looks at how much radioactive decay
has occurred in an object to determine the age.

9. Drawing out Radioactive Decay

10. Drawing out Radioactive Decay

11. Drawing out Radioactive Decay
250,000
years old

12. Drawing out Radioactive Decay
250,000
years old
500,000
years old

13. Drawing out Radioactive Decay
750,000
years old
250,000
years
250,000
years
250,000
years
250,000
years old
500,000
years old