Radiochemical dating spacer dating
For example, uranium-lead dating can be used to find the age of a uranium-containing mineral.
It works because we know the fixed radioactive decay rates of uranium-238, which decays to lead-206, and for uranium-235, which decays to lead-207.
Once incorporated into the otolith, the radioisotopes decay into radioactive daughter products, which are themselves retained within the acellular crystalline structure.
Since the half-lives of the parent and daughter isotopes are known (and fixed), the ratio between them is an index of elapsed time since incorporation of the parent isotope into the otolith.
Radiometric dating is used to estimate the age of rocks and other objects based on the fixed decay rate of radioactive isotopes.
Learn about half-life and how it is used in different dating methods, such as uranium-lead dating and radiocarbon dating, in this video lesson. As we age, our hair turns gray, our skin wrinkles and our gait slows.
This provides a built-in cross-check to more accurately determine the age of the sample.
However, the extracted otolith core reflects elapsed time since core formation, which in turn is very similar to the age of the fish.
Since interpretation of the otolith core also avoids the problematic assumptions, it is widely acknowledged to provide more reliable results than would the whole otolith.
So, we start out with two isotopes of uranium that are unstable and radioactive.
They release radiation until they eventually become stable isotopes of lead.
However, rocks and other objects in nature do not give off such obvious clues about how long they have been around.