Relative dating methods allow one to determine if an object is earlier than, later than, or contemporary with some other object.
It does not, however, allow one to independently assign an accurate estimation of the age of an object as expressed in years.
This number is usually written as a range, with plus or minus 40 years (1 standard deviation of error) and the theoretical absolute limit of this method is 80,000 years ago, although the practical limit is close to 50,000 years ago.
Because the pool of radioactive carbon in the atmosphere (a result of bombardment of nitrogen by neutrons from cosmic radiation) has not been constant through time, calibration curves based on dendrochronology (tree ring dating) and glacial ice cores, are now used to adjust radiocarbon years to calendrical years.
The most common archaeological methods, however, involve the slow removal of relics, remains and other evidence from sites that have been buried for hundreds or thousands of years.
This technique, called excavation, is often done by hand and involves rigorously scientific protocols.
If archaeologists know how pottery styles, glazes, and techniques have changed over time they can date sites based on the ratio of different kinds of pottery.
These strata are often most visible in canyons or gorges which are good sites to find and identify fossils.
Understanding the geologic history of an area and the different strata is important to interpreting and understanding archaeological findings.
Archaeological methods have been refined over the decades to uncover as much data as possible about the societies that left this evidence.
In the past, archaeology was sometimes performed without the consent of local populations, often at the behest of occupying imperial nations.