Seventy years ago, American chemist Willard Libby devised an ingenious method for dating organic materials. His technique, known as carbon dating, revolutionized the field of archaeology. Now researchers could accurately calculate the age of any object made of organic materials by observing how much of a certain form of carbon remained, and then calculating backwards to determine when the plant or animal that the material came from had died. An isotope is a form of an element with a certain number of neutrons, which are the subatomic particles found in the nucleus of an atom that have no charge. While the number of protons and electrons in an atom determine what element it is, the number of neutrons can vary widely between different atoms of the same element.
Carbon Dating Could Stop Working as Earth's Atmosphere Ages Prematurely - The Atlantic
There's quite a few, all of which are types of radioactive dating. They include potassium-argon dating, that's useful for rocks over , years old. There's also uranium-lead dating, which has an age range of It can be used for such long time spans because the half-life of uranium turning into lead is billions of years, in the order of the age of the Earth at 4. Mike, from Cambridge, also called in to remind us about thermo-luminescence which can be used in pottery, also obsidian hydration and uranium trail dating when you observe the trails left behind by uranium decomposition. Skip to main content. Earth Science.
Ivory appraisal, identification and pre-ban certification
It has long been known that radioactive isotopes in the atmosphere have made carbon dating of all kinds of materials possible. Radioactive carbon released from nuclear bomb tests during the Cold War is one way of dating more recent materials. That method is now being used to help fight the illegal trade in elephant ivory.
Elephant poaching is alive and well — and the elephants are not. A team of scientists examining seized shipments of elephant ivory from Africa have found that the vast majority came from elephants that died within the last three years. The sobering results , published this week in the Proceedings of the National Academy of Sciences, reveal that the killing of elephants for their ivory is continuing at a disturbing pace — even as elephant populations across the continent are in sharp decline. While poaching had been easing for several years, it has returned with a vengeance in the last decade or so, said study lead author Thure E.