Dating Fossils - Absolute Dating

Question 1

What is the advantage of absolute dating compared to relative dating?

Answer 1

Provides a more precise estimate of the age of fossil/rock layer

Question 1

What are isotopes?

Answer 1

Different versions of the same element

Question 2

What are radioactive isotopes?

Answer 2

Isotopes that naturally decay over time from one isotope to another

Question 3

What are half-lives of a radioactive isotope

Answer 3

The time taken for a certain amount of isotope to half

Question 4

How does radiometric dating use half-lives of radioactive isotopes to date fossils?

Answer 4

Measures the proportion of the isotope present and calculates the age considering the constant rate of decay

Question 5

How can the constant rate of decay be calculated?

Answer 5

By taking the original amount of isotope (which is present in all rocks.creatures in same amount) and using half life to calculate time passed

Question 6

What are the 4 isotopes used to date fossils and organic remains?

Answer 6

1. Carbon-14
2. Uranium-235
3. Potassium-40
4. Rubidium-87

Question 7

What type of dating is carbon dating used for and why?

Answer 7

• Used to date organic remians
• When any organism dies, it has same ratio of Crabon-12 to Carbon-14
• Carbon-14, however, decays.
• Comparing the ratio of C-14 to C-12 allows an estimate of time since death to be made

Question 8

How many years old organic remains can be dated by Carbon-14

Answer 8

• Useful for ages up to about 60 000 years old
• Half life of 5 730

Question 9

What type of dating is Uranium-235 useful for and how old?

Answer 9

• Useful for dating igneous rocks containing uranium based minerals
• Can date from 10 million years and older
• Half-life of 710 000 000

Question 10

What type of dating is Potassium-40 useful for and how old?

Answer 10

• Useful for dating igneous rock containing Potassium based minerals
• Can date from range 0.5 million years old and older
• Half-life of 1 300 000 000

Question 11

What type of dating is Rubidium-87 useful for and how old?

Answer 11

• Can be used to date the most ancient igneous rocks on planet earth
• Half-life of 47 000 000 000

Question 12

Briefly describe thermoluminescence dating

Answer 12

• Can date objects up to 500 000 years old
• Measures intensity of light emitted by minerals when heated
• Light emmitted is proportional to amount of radiation absorbed (older minerals emitt stronger light)

Don’t need to know really

Question 13

Breifly describe electron spin resonance dating

Answer 13

• Measures the magnetism of certain minerals
• Magnetism is caused by electrons trapped within minerals due to radiation
• More magnetism for older minerals