Types of radio dating
Relative age dating also means paying attention to crosscutting relationships.
Say for example that a volcanic dike, or a fault, cuts across several sedimentary layers, or maybe through another volcanic rock type.
Here is an easy-to understand analogy for your students: relative age dating is like saying that your grandfather is older than you.
Absolute age dating is like saying you are 15 years old and your grandfather is 77 years old.
For example, an object with a quarter of its original amount (2x1/2) should be roughly 11,460 years old.
In all radiometric procedures there is a specific age range for when a technique can be used.
This technique is not restricted to bones; it can also be used on cloth, wood and plant fibers.
A useful application of half-lives is radioactive dating.
Radiocarbon decays slowly in a living organism, and the amount lost is continually replenished as long as the organism takes in air or food.
Once the organism dies, however, it ceases to absorb carbon-14, so that the amount of the radiocarbon in its tissues steadily decreases.
In radiometric dating, the decaying matter is called the parent isotope and the stable outcome of the decay is called the daughter product.
Since the half-life of carbon-14 is 5730 years, scientists can measure the age of a sample by determining how many times its original carbon-14 amount has been cut in half since the death of the organism.