Absolute dating relative
When light is used rather than heat to free the accumulated electrons, the technique is known as optically stimulated resonance.
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.
In dendrochronology, the age of wood can be determined through the counting of the number of annual rings in its cross section.
By this method the age of the earth is estimated to be about 4.5 billion years old.
Because rainfall patterns vary annually, any given set of tree ring patterns in a region will form a relatively distinct pattern, identifiable with a particular set of years.
By comparing the pattern of tree rings in trees whose lifespans partially overlap, these patterns can be extended back in time.
All of these techniques have proven somewhat unreliable.
Museums sometimes use them to determine if a ceramic is an antique or a modern forgery.Furthermore, Egyptian trade wares were used as a basis for establishing the age of the relative chronologies developed for adjoining regions, such as Palestine and Greece.