These radioactive isotopes are parent isotopes, which decay slowly to daughter isotopes, changing the rock’s isotopic character.The rate at which the isotopes decay is in effect our "geological clock".On the other hand, absolute dating includes all methods that provide figures about the real estimated age of archaeological objects or occupations.These methods usually analyze physicochemical transformation phenomena whose rate are known or can be estimated relatively well.Absolute dating entails laboratory analysis of rock samples that will take a longer time.further, the dating results will still have to be cross-checked with mapping data.
This law follows two basic assumptions: (1) the beds were originally deposited near horizontal, and (2) the beds were not overturned after their deposition.
Cultural seriations are based on typologies, in which artifacts that are numerous across a wide variety of sites and over time, like pottery or stone tools.
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.
By measuring the amount of the parent and daughter isotopes in a crystal, and then applying the decay rate, the actual age in years since the rock crystallized can be calculated.
Check out this video on the Uranium – Lead dating method: Biostratigraphy is a relative dating method that correlates rock ages using the fossils contained within rock units.