Principle of carbon dating
This 'law of superimposition' works in the well-defined layers of the Willandra lunettes, but only dates objects as younger or older than adjacent layers.To determine the year age (absolute age) of an object, a number of chemical and radioactive techniques can be used.The method also assumes a 'zeroing' event in the life of the material, when it was either last heated or exposed to sunlight.Dating, in geology, determining a chronology or calendar of events in the history of Earth, using to a large degree the evidence of organic evolution in the sedimentary rocks accumulated through geologic time in marine and continental environments.Carbon-14 has a half-life of 5,730 years so dating is limited to between a few hundred and about 50,000 years. It is also important that samples for dating are collected carefully to ensure they have not been contaminated with more recent carbon.Radiocarbon analysis can only be used on organic materials, and is often used to date charcoal associated with campfires and archaeological deposits.
It is most useful for minerals older than 100,000 years and can reach way back into the geological past.
Four main methods have been used in Willandra archaeology.
This well known method was the first technique that became available for accurate dating of old materials.
This technique can determine ages between a few hundred years to more than 100,000 years.
It has been used at Willandra to date the layers above and below the location of Mungo Lady and Mungo Man , and the layers above and below the footprints horizon.