History of archaeological dating
Absolute dating represents the absolute age of the sample before the present.
Historical documents and calendars can be used to find such absolute dates; however, when working in a site without such documents, it is hard for absolute dates to be determined.
In a stratigraphical context objects closer to the surface are more recent in time relative to items deeper in the ground.
Although relative dating can work well in certain areas, several problems arise.
Shellfish remains are common in coastal and estuarine archaeological sites, but dating these samples require a correction for the “reservoir effect” a process whereby "old carbon" is recycled and incorporated into marine life especially shellfish inflating their actual age in some cases several centuries.
In recognition of this problem archaeologists have developed regional reservoir correction rates based on ocean bottom topography, water temperature, coastline shape and paired samples of terrestrial and marine objects found together in an archaeological feature such as a hearth.
When it comes to dating archaeological samples, several timescale problems arise.
For example, Christian time counts the birth of Christ as the beginning, AD 1 (Anno Domini); everything that occurred before Christ is counted backwards from AD as BC (Before Christ).
Relative dating stems from the idea that something is younger or older relative to something else.
The Mayan calendar used 3114 BC as their reference.
More recently is the radiocarbon date of 1950 AD or before present, BP.
In 1949, American chemist Willard Libby, who worked on the development of the atomic bomb, published the first set of radiocarbon dates.
His radiocarbon dating technique is the most important development in absolute dating in archaeology and remains the main tool for dating the past 50,000 years.In fact, levels of Carbon-14 have varied in the atmosphere through time.