Radiometric dating of planets
This is because it is not possible for a younger layer to slip beneath a layer previously deposited.
The only disturbance that the layers experience is bioturbation, in which animals and/or plants move things in the layers.
The Permian through Jurassic stratigraphy of the Colorado Plateau area of southeastern Utah is a great example of Original Horizontality and the Law of Superposition, two important ideas used in relative dating.
These strata make up much of the famous prominent rock formations in widely spaced protected areas such as Capitol Reef National Park and Canyonlands National Park.
Explanations: A – folded rock strata cut by a thrust fault; B – large intrusion (cutting through A); C – erosional angular unconformity (cutting off A & B) on which rock strata were deposited; D – volcanic dyke (cutting through A, B & C); E – even younger rock strata (overlying C & D); F – normal fault (cutting through A, B, C & E).
The principle of cross-cutting relationships pertains to the formation of faults and the age of the sequences through which they cut.
Though relative dating can only determine the sequential order in which a series of events occurred, not when they occurred, it remains a useful technique.
The principle of original horizontality states that the deposition of sediments occurs as essentially horizontal beds.
The principle of inclusions and components states that, with sedimentary rocks, if inclusions (or clasts) are found in a formation, then the inclusions must be older than the formation that contains them.
For example, in sedimentary rocks, it is common for gravel from an older formation to be ripped up and included in a newer layer.
There are a number of different types of intrusions, including stocks, laccoliths, batholiths, sills and dikes.
Cross-cutting relations can be used to determine the relative ages of rock strata and other geological structures.