Dating 2 relating
The principle of inclusions and components explains 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.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.A fundamental principle of geology advanced by the 18th century Scottish physician and geologist James Hutton, is that "the present is the key to the past." In Hutton's words: "the past history of our globe must be explained by what can be seen to be happening now." The principle of intrusive relationships concerns crosscutting intrusions.
Prior to the discovery of radiometric dating in the early 20th century, which provided a means of absolute dating, archaeologists and geologists used relative dating to determine ages of materials.
however, this process is not enough to allow the layers to change their positions.