Advantages of relative dating techniques in archaeology
Thus it is possible to measure the time that has elapsed since the material solidified.
Thermoluminescence, used in dating archaeological material such as pottery, is based on the luminescence produced when a solid is heated; that is, electrons freed during radioactive decay and trapped in the crystal lattice are released by heating, resulting in luminescence.
Some of the radioactive elements used in dating and their decay products (their stable daughter isotopes) are uranium-238 to lead-206, uranium-235 to lead-207, thorium-232 to lead-208, samarium-147 to neodymium-143, rubidium-87 to strontium-87, and potassium-40 to argon-40.
Each radioactive member of these series has a known, constant decay rate, measured by its half-life, that is unaffected by any physical or chemical changes.
By counting each pair of varves the age of the deposit can be determined.
The absolute dating methods most widely used and accepted are based on the natural radioactivity of certain minerals found in rocks.
The conventional method of measuring the amount of radioactive carbon-14 in a sample involved the detection of individual carbon-14 decay events. This technique involves the direct counting of carbon-14 atoms through the use of the accelerator mass spectrometer and has the advantage of being able to use sample sizes up to 1,000 times smaller than those used by conventional radiocarbon dating.Absolute dating can be achieved through the use of historical records and through the analysis of biological and geological patterns resulting from annual climatic variations, such as tree rings (dendrochronology) and varve analysis.