Inclusion relative dating
This method has been developed as part of paleontology – science concerned with fossils and development of life through geological history.
In determining the chronology of rocks and facies of all marine, mixed and continental sediments, the fluctuations and changes in the order of land and sea in Earth’s past are followed.His own ideas of what was important were quite different, but I think they are still well worth considering.He put forth three propositions, the first being this: "If a solid body is enclosed on all sides by another solid body, of the two bodies that one first became hard which, in the mutual contact, expresses on its own surface the properties of the other surface." (This may be clearer if we change "expresses" to "impresses" and switch "own" with "other.") While the "official" Principles pertain to layers of rock and their shapes and orientations, Steno's own principles were strictly about "solids within solids." Which of two things came first? Thus he could confidently state that fossil shells existed before the rock that enclosed them.And we know of many more causes, from tectonics to intrusions, that can tilt and fold rocks.This principle allowed Steno to link identical rocks on opposite sides of a river valley and deduce the history of events (mostly erosion) that separated them.It explains just what it is about mineral crystals that make them distinct and identifiable even when their overall shapes may differ—the angles between their faces.
It gave Steno a reliable, geometrical means of distinguishing minerals from each other as well as from rock clasts, fossils and other "solids embedded in solids." Steno did not call out his Law and his Principles as such.
Today we apply this principle across the Grand Canyon—even across oceans to link continents that once were adjoined.
This principle is essential in studying all kinds of rocks, not just sedimentary ones.
Radioactive elements emit α and β particles, as well as γ rays, thus causing their mass to reduce over time, shifting eventually to stabile isotopes.
The final stabile product (isotope) can be compared in quantity to the original radioactive element.
The age of a rock is determined by stratigraphy, a branch in geology which studies the chronology of events and changes, along with the development of organisms, which have determined the development of the Earth from when it became an independent spatial body until today.