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Absolute Age
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Absolute Age
•Absolute Age—the number age of a rock or an objectExample—Mr. Choi is 14 years old.
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?
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?
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?
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.
Absolute Age• Radioactive Decay—the process where an unstable element becomes stableExample: Radioactive Uranium Stable Lead
Radioactive Carbon Stable Nitrogen
Absolute Age• Radiometric dating—looks at how much radioactive decay has occurred in an object to determine the age.
Drawing out Radioactive Decay
Drawing out Radioactive Decay
Drawing out Radioactive Decay
250,000 years old
Drawing out Radioactive Decay
250,000 years old
500,000 years old
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
