Obsidian hydration relative dating
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.
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.
Yet another technique measures the quantity of trapped electrons by detecting the amount of microwave radiation they absorb (electron-spin resonance); it has the advantage that it can be utilized several times on a given sample.
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, uranium-234 to thorium-230, 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.
The accelerator mass spectrometer technique reduces the amount of statistical error involved in the process of counting carbon-14 ions and therefore produces dates that have smaller standard errors than the conventional method.
Paleomagnetic dating is based on changes in the orientation and intensity of the earth's magnetic field that have occurred over time.