Stratigraphy Inspired by geology, stratigraphy uses the principle of the superposition of strata which suggests that, in a succession of undisturbed SOILS, the upper horizons are newer than the lower ones.Generally, each stratum is isolated in a separate chronological unit that incorporates artifacts.The bones were buried under (and are therefore older) a layer of ash that resulted from a volcanic eruption dating back to 7000 years BP (Before Present; "present" indicates c. Subsequently, radiocarbon dating, an absolute dating technique, was used to date the bones directly and provided a date of 8250 BP, showing how useful the combined used of relative and absolute dating can be.
An initial reading dates the specimen which is then calibrated by considering this date and its correspondence with the measurable level of carbon 14 stored over time in the growth rings of certain tree species, including redwood and pine bristol.
The results of radiocarbon dating are expressed in years and include a time range (eg, 630± 60 BP).
This method is primarily applied to projectile points and ceramic vessels.
These present many characteristics that are used for comparing them, such as morphology and raw materials in the case of stone tools, and decorative techniques and motifs in the case of ceramics.
Stratigraphic dating remains very reliable when it comes to dating objects or events in undisturbed stratigraphic levels.
For example, the oldest human remains known to date in Canada, found at Gore Creek, have been dated using soil stratification.Indeed, some items whose exact or approximate age is known are called "diagnostic artifacts." Examples of such objects include very specific stone tools, different pottery styles, objects that belong to a specific period (eg, the historic period or the French regime), coins with a production date, or other items bearing a trademark and whose history can be traced in historical records.Their presence on archaeological sites is used to date the soil layers and the objects and events they are associated with and thus contributes to refine the chronology of sites.There are two main categories of dating methods in archaeology: indirect or relative dating and absolute dating.Relative dating includes methods that rely on the analysis of comparative data or the context (eg, geological, regional, cultural) in which the object one wishes to date is found.Subsequently, the calibration of that date provides a time interval where the event or object being dated can be situated (eg, 1275-1425 AD).