Absolute dating methods are methods that return a specific date, in years, for the formation of a fossil or sediment layer.

Often this date is given as a range of years, for example, 3.5 mya /- 35ky (that would be read as 3.5 million years ago, plus or minus 35 thousand years).

For example, carbon has three isotopes: 12C (or Carbon-12), 13C (Carbon-13), and 14C (Carbon-14).

Radiometric dating is used to estimate the age of rocks and other objects based on the fixed decay rate of radioactive isotopes.

Radiometric dating techniques are based on the principle of radioactive decay.

Essentially, elements, such as carbon (C) or potassium (K), have more than one isotopic form, or variation based on atomic weight.

Scientists first developed absolute dating techniques at the end of the 19th century.

So, if you know the radioactive isotope found in a substance and the isotope's half-life, you can calculate the age of the substance. Well, a simple explanation is that it is the time required for a quantity to fall to half of its starting value.Chronometric dating has advanced since the 1970s, allowing far more accurate dating of specimens.Adrian Grahams began writing professionally in 1989 after training as a newspaper reporter.For example, a geologist may examine a cutting where the rocks appear as shown in Figure 1.Here he can see that some curved sedimentary rocks have been cut vertically by a sheet of volcanic rock called a dyke.His work has been published online and in various newspapers, including "The Cornish Times" and "The Sunday Independent." Grahams specializes in technology and communications.He holds a Bachelor of Science, postgraduate diplomas in journalism and website design and is studying for an MBA.Mikhail Marov of the Vernadsky Institute of Geochemistry and Analytical Chemistry said scientists had determined the meteorite's age by observing the amount of radioactive isotopes and their decay byproducts, a technique called of a granodiorite at the Cuttaburra A prospect indicates that this mineralised system may be Middle Silurian in age and thus indicating that the host rocks are older than those hosting the Cobar-type deposits. The study of human evolution was revolutionized by the development of absolute dating methods in the 1950s and 1960s.any method of determining the age of earth materials or objects of organic origin based on measurement of either short-lived radioactive elements or the amount of a long-lived radioactive element plus its decay product.A method for determining the age of an object based on the concentration of a particular radioactive isotope contained within it.Archaeologists and scientists use absolute dating methods on samples ranging from prehistoric fossils to artifacts from relatively recent history.Chronometric techniques include radiometric dating and radio-carbon dating, which both determine the age of materials through the decay of their radioactive elements; dendrochronology, which dates events and environmental conditions by studying tree growth rings; fluorine testing, which dates bones by calculating their fluorine content; pollen analysis, which identifies the number and type of pollen in a sample to place it in the correct historical period; and thermoluminescence, which dates ceramic materials by measuring their stored energy.Radiocarbon dating is one kind of radiometric dating, used for determining the age of organic remains that are less than 50,000 years old.