Relative dating stratigraphy
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.
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One of the most widely used methods of determining the absolute date of organic materials is radiocarbon (carbon 14) dating .
Because all living organisms contain a radioactive form of carbon (carbon 14) that decays at a known and steady rate, archaeologists can determine an organic object's age (if it is less than 40,000 years old) by measuring the amount of carbon 14 remaining in the object.
The style of the artefact and its archaeology location stratigraphically are required to arrive at a relative date.
These methods usually analyze physicochemical transformation phenomena whose rate are known or can be estimated relatively well.This problem is now reduced by the careful collection of samples, rigorous crosschecking and the use of newer techniques that can date minute samples.Volcanic rocks – such as tuff and basalt – can be used in dating because they are formed at a particular moment in time, during an eruption.In relative dating, archaeologists interpret artifacts based on their positions within the (horizontal layering) of the soil.The study of stratigraphy follows the excavation axiom "last in, first out"--meaning that an archaeologist usually removes soil layers in the reverse order in which they were laid down (see Figure 1).