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.
those that form during chemical reactions without breaking down).
The unstable or more commonly known radioactive isotopes break down by radioactive decay into other isotopes.
Also, if radiocarbon ages are to be compared to calendar ages then detailed knowledge about the long-term production of C in the atmosphere is needed.
Optical dating, on the other hand, is used to determine the time elapsed since last exposure of quartz or feldspar grains (the two most common minerals on Earth) to sunlight or heat (Lian and Roberts 2006).
In a way this field, called geochronology, is some of the purest detective work earth scientists do.
“To measure noble gas isotopes for geochronology on Earth, we had used large high-resolution sector mass spectrometers,” Professor Vasconcelos said.
Radioactive decay is a natural process and comes from the atomic nucleus becoming unstable and releasing bits and pieces.
These are released as radioactive particles (there are many types).
To determine the relative age of different rocks, geologists start with the assumption that unless something has happened, in a sequence of sedimentary rock layers, the newer rock layers will be on top of older ones. This rule is common sense, but it serves as a powerful reference point.
Geologists draw on it and other basic principles ( to determine the relative ages of rocks or features such as faults.