Here's why:
* Carbon-14 dating is only suitable for organic materials. Carbon-14 is a radioactive isotope of carbon that decays at a known rate. This method works because living organisms constantly exchange carbon with their environment, maintaining a constant level of carbon-14. When an organism dies, the carbon-14 starts to decay, and the remaining amount can be used to estimate the time of death.
* Igneous rocks are formed from molten rock. They do not contain the organic materials necessary for carbon-14 dating.
Instead of carbon-14, scientists use other radioactive isotopes like potassium-argon (K-Ar) or uranium-lead (U-Pb) dating to determine the age of igneous rocks. These isotopes are present in the minerals within igneous rocks, and their decay rates are well-understood.
