warm-up how do scientists use ‘relative dating?’
Post on 08-Jan-2018
220 Views
Preview:
DESCRIPTION
TRANSCRIPT
Warm-up1. How do scientists use ‘relative
dating?’2. Which layer is the oldest?3. Which layer is the youngest?4. Which layers are older than the
fault line B?
Penny Lab
Absolute DatingAKA Radiometric dating
Determines ‘exact’ age.Examples:◦Dinosaurs went extinct 65 million years ago.
◦Trey was born on June 29, 2000.
Radioactive DecayRadioactive ElementsUnstable parent nuclei
becoming stable daughter nuclei◦Gives off energy◦Constant rate
By measuring how much of each type of radioactive element is present scientists can determine a rocks age.
Half-LifeAmount of time it
takes for half of the amount of a radioactive element to decay into another element.
Uranium-235Potassium-40Carbon-14
Carbon DatingMany forms of carbon
Carbon-14◦Radioactive◦Living - continuous
replacement◦Dead – amount decreases◦Half-life = 5,730 years
By measuring the amount of Carbon-14 remaining in the specimen scientists can determine its age.
Carbon Dating
Think through the math:If there is 50% of the
original amount of 14C in a specimen it is 5730 years old.
If you find a specimen that has only 25% of the original 14C, it has gone through 2 half-lives.
◦This specimen is (5730x2) years old = 11,460 years old.
Carbon Dating: Fill in this Chart!
Half-Life % Carbon Left
Age in Years
1 50% 5,730 2 25% 11,460 3 12.5% 17,190 4 6.25% 22,920 5 3.125% 28,6506 1.563% 34,3807 0.781% 40,110
You are a CSI Detective…
You found a skeleton that contains 12.5% of it’s original carbon.
1. How many half lives have passed?
2. How old is it? (how long ago did this person die?)
You are an anthropologist and found this animal!This skeleton contains 3.125% of it’s original carbon.1. How many half lives have passed?2. How old is it?
top related