Potassium argon dating advantages and disadvantages
Although this article highlights a brief overview of two basic types of geologic dating, it is not meant to represent all methods of dating, and it is also not meant to be a comprehensive review of relative and absolute methods.
These break down over time in a process scientists call radioactive decay.
The Law of Superposition indicates that the oldest layers will be on the bottom, the youngest on the top.
Likewise, the Law of Cross-Cutting Relationships holds that any igneous intrusion or physical change such as faulting, must have occurred after the deposition of the strata that it cuts through, and thus, must be older than those particular rocks.
When an unstable radioactive isotope, or parent, decays or loses radiation such as a beta particle, antineutrino or a gamma ray, a daughter product is left behind.
The time it takes for an unstable nucleus to decay to the daughter product is called a half-life.