Carbon dating

• Allahabad HC ordered carbon dating of a structure at Gyanvapi mosque complex in Varanasi.
• Carbon dating is a widely-used method to establish the age of organic materials, things that were once living.
• Carbon-14 (C-14), an isotope of carbon, is radioactive, and decays at a well-known rate (Half-life of 5,730 years).
• Most abundant isotope of carbon in atmosphere is C-12.
• Ratio of C-12 to C-14 in atmosphere is almost static, and is known.
• Also, age of things that are more than 40,000-50,000 years cannot be arrived at through carbon dating.
• This is because after 8-10 cycles of half-lives, the amount of C-14 becomes very small and is almost undetectable.

OTHER RADIOMETRIC DATING METHODS

• Two commonly employed methods for dating rocks are potassium-argon dating and uranium-thorium-lead dating.
• The radioactive isotope of potassium decays into argon, and their ratios can give a clue about the age of rocks.
• Uranium and thorium have several radioactive isotopes, and all of them decay into the stable lead
• The ratios of these elements present in the material can be measured and used to make estimates about age.