Dating techniques tend to be very important to archaeologists. Absolute dating is a way to get the date of something in the most accurate way possible.

Absolute dating which is also known as chronometrical dating has techniques that include: dendrochronology (study of tree ring patterns), Archaeomagnetism (based on fact that changes in the earth's magnetic field over time can be recorded as remnant magnetism in certain materials, e.g., baked clay), and radioactive dating such as radiocarbon/C-14, thermoluminescence, and potassium argon. These latter techniques are based on the principles of radioactive decay, the process by which radioactive isotopes break down into their decay products with a half-life specific to the isotope in question. Half life refers to the time taken for half the quantity of a radioactive isotope in a sample to decay.

There are many ways in which the absolute date of something can be achieved. Some of those methods are tree growth rings, coral growth cycles, and varves (annual clay sediment layers). These methods rely on the decay of the naturally occurring radiogenic isotopes shown in the table to the right.

Uranium, Thorium, and Potassium are by far the most common radiogenic isotopes in the Earth's crust. Radiocarbon is important in dating organic remains from the relatively recent past.

Radioactivity is the most commonly used method. It is defined as the spontaneous adjustment of nuclei of unstable atoms to a more stable state.

References

University of Saskatchewan   http://www.usask.ca/

University of California - Berkley Archaeology Department - http://www.dla.utexas.edu/depts/anthro/courses/97fall/denbow304/wk1and2.html