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.
Realative dating age of rocks
For example, in sedimentary rocks, it is common for gravel from an older formation to be ripped up and included in a newer layer.
A similar situation with igneous rocks occurs when xenoliths are found.
From top to bottom: Rounded tan domes of the Navajo Sandstone, layered red Kayenta Formation, cliff-forming, vertically jointed, red Wingate Sandstone, slope-forming, purplish Chinle Formation, layered, lighter-red Moenkopi Formation, and white, layered Cutler Formation sandstone.
Picture from Glen Canyon National Recreation Area, Utah.
He also found that certain animals were in only certain layers and that they were in the same layers all across England.
Due to that discovery, Smith was able to recognize the order that the rocks were formed.
In geology, when an igneous intrusion cuts across a formation of sedimentary rock, it can be determined that the igneous intrusion is younger than the sedimentary rock.
There are a number of different types of intrusions, including stocks, laccoliths, batholiths, sills and dikes.
Sixteen years after his discovery, he published a geological map of England showing the rocks of different geologic time eras.
Methods for relative dating were developed when geology first emerged as a formal science.
These foreign bodies are picked up as magma or lava flows, and are incorporated, later to cool in the matrix.