3 assumptions of radiometric dating
Concordia dating is a form of uranium/lead dating that uses a concordia diagram.
The theory is that when zircons crystallize they lose all of their lead and as long as the crystal remains closed its lead/uranium ratios should follow a predictable trend.
In dating any object, geologists: When dating an object, a geologist measures some physical property of the object, which is believed to provide evidence regarding its age.
Dendrochronology is a technique of dating past climatic changes through a study of tree ring growth.
It is from this field of study that fossils and artifacts are dated based on the perceived age of the geological layers in which they are located.