How relative dating is done
Archaeologists use many different techniques to determine the age of a particular artifact, site, or part of a site.Two broad categories of dating or chronometric techniques that archaeologists use are called relative and absolute dating.
Numerical techniques are best, but datable materials are often lacking, and in these cases age estimation must be made using relative-dating or correlation techniques.Geologic studies of active tectonism are greatly aided by definition and time calibration of local stratigraphic sequences.Because all dating techniques may be subject to considerable error, reliability should be assessed by stratigraphic consistency between results of different dating methods or of the same method.The scholar most associated with the rules of stratigraphy (or law of superposition) is probably the geologist Charles Lyell.The basis for stratigraphy seems quite intuitive today, but its applications were no less than earth-shattering to archaeological theory.Knowing when a dinosaur or other animal lived is important because it helps us place them on the evolutionary family tree.
Accurate dates also allow us to create sequences of evolutionary change and work out when species appeared or became extinct. These are: Where possible, several different methods are used and each method is repeated to confirm the results obtained and improve accuracy.
We do this all the time in our regular day to day lives.
For example, lets put the following movies in order of relative age from oldest to youngest: Twilight, Finding Nemo, the Avengers, the Hunger Games.
In other words, artifacts found in the upper layers of a site will have been deposited more recently than those found in the lower layers.
Cross-dating of sites, comparing geologic strata at one site with another location and extrapolating the relative ages in that manner, is still an important dating strategy used today, primarily when sites are far too old for absolute dates to have much meaning.
Relative-dating techniques are nearly always applicable but are not precise and require calibration.