A method known as absolute dating can determine the unknown age of ancient artifacts.
Archaeological objects having known dates could be helpful in finding the unknown age of a certain discovered artifact. Recording of dates can be traced back to as early as 3,000 B.C. in the Southwestern part of Asia. Examples of objects having written dates are coins and pots. The time period on which these materials were created was already dated. So to say, it can be compared to artifacts whose ages are still unknown. The only limitation of using this method is the object found has to have the capability of being dated after written records occurred. Objects having ages that can be compared to preliterate periods can't be determined by use of this method.
Tree rings, which have developed over time on ancient trees, are also used in a method known as dendrochronology or tree-ring dating. The development of these rings depends on the amount of rainfall it receives each year. Since the rings determine a tree's age, it could serve as a pattern to be compared to other objects made of wood. Examples of these are house posts from New Mexico. These ring patterns also reflect if on a certain time a tree has lived through moments of drought.
In 1949, an American chemist named Willard Libby developed a dating technique that is now the most widely used by archaeologists. This is known as radiocarbon dating. It can date objects as old as 8, 000-10,000 years old. It works by measuring the amount of carbon isotope C-14 remaining on materials like bones and shells. C-14 is formed when space neutrons enter the earth's atmosphere and coagulate with nitrogen. Prehistoric matter, like rocks, can be dated with potassium-argon dating. The earth's crust contains an element called potassium. While minerals contain this element, they undergo geologic changes and cause the potassium present in it to decay at a known level into Ar-40(argon 40)gas. An instrument called a spectrometer indicates the amount of Ar-40 out of the original amount of potassium a substance contains. This determines its age. Other methods include the (ESR) electron spin resonance and uranium series dating. ESR calculates the amount of electrons that accumulates in bone samples. Uranium series dating can be used to measure the age of substances stuck in rocks. It is done by determining the radioactive decay of uranium isotopes in rocks made of calcium carbonates like calcite.
