Narrow rings grow in cold or dry years, and wide rings grow in warm or wet years.
The rings form a distinctive pattern, which is the same for all members in a given species and geographical area.
When the organism dies, the supply stops, and the carbon-14 contained in the organism begins to spontaneously decay into nitrogen-14.
Absolute dating methods are carried out in a laboratory.The older the pottery, the brighter the light that will be emitted.Using thermoluminescence, pottery pieces as old as 100,000 years can be dated with precision. Known as dendrochronology (pronounced den-dro-crow-NOL-o-gee), tree-ring dating is based on the fact that trees produce one growth ring each year.These include the uranium-thorium method, the potassium-argon method, and the rubidium-strontium method. Thermoluminescence (pronounced ther-moeloo-mi-NES-ence) dating is very useful for determining the age of pottery.When a piece of pottery is heated in a laboratory at temperatures more than 930°F (500°C), electrons from quartz and other minerals in the pottery clay emit light.Before the advent of absolute dating methods in the twentieth century, nearly all dating was relative.