1. Radioactive Isotopes: Certain elements in rocks and fossils are radioactive, meaning they decay at a predictable rate. These are called radioactive isotopes.
2. Half-Life: Each radioactive isotope has a specific half-life, which is the time it takes for half of the radioactive atoms in a sample to decay into a stable form.
3. Measuring Ratios: Geologists measure the ratio of the original radioactive isotope to the stable daughter isotope.
4. Calculating Age: By comparing the measured ratio to the known half-life, they can calculate the time it took for the decay to occur, which is the age of the fossil or rock.
Commonly used radioactive isotopes for dating fossils:
* Carbon-14: Used for dating relatively young fossils (up to 50,000 years old)
* Potassium-40: Used for dating older fossils and rocks (up to billions of years old)
* Uranium-238: Used for dating very old rocks and fossils (up to billions of years old)
Important Note: Radiometric dating is not directly applied to the fossil itself. Instead, it's used to date the surrounding rocks that contain the fossil. This helps determine the age of the rock layer and, by extension, the fossil embedded within it.
