In relative soil dating, archaeologists follow two general principles known as refers to the concept that all the soil below a solid, undisturbed layer dates before that layer (see Figure 3).
Relative dating of a site's stratigraphy often depends on the absolute dating of excavated materials and artifacts.
The New Zealand curve is representative for the Southern Hemisphere, the Austrian curve is representative for the Northern Hemisphere. This makes it possible to tell the age of substances that contain carbon. Dates obtained are usually written as before present ('present' is 1950).
Atmospheric nuclear weapon tests almost doubled the concentration of Radiocarbon dating, also known as the C14 dating method, is a way of telling how old an object is. Plants take up atmospheric carbon dioxide by photosynthesis, and are eaten by animals, so every living thing is constantly exchanging carbon-14 with its environment as long as it lives. In 1958 Hessel de Vries showed that the concentration of carbon-14 in the atmosphere varies with time and locality.
In relative dating, archaeologists interpret artifacts based on their positions within the (horizontal layering) of the soil.
Another way of dating pottery and other inorganic materials is through .
Luminescence dating (including thermoluminescence and optically stimulated luminescence) is a type of dating methodology that measures the amount of light emitted from energy stored in certain rock types and derived soils to obtain an absolute date for a specific event that occurred in the past.
The method is a direct dating technique, meaning that the amount of energy emitted is a direct result of the event being measured.
For the most accurate work, variations are compensated by means of calibration curves.
The method was developed by Willard Libby and his colleagues at the University of Chicago in 1949.