Carbon dating method
’s free newsletters."data-newsletterpromo-image="https://static.scientificamerican.com/sciam/cache/file/458BF87F-514B-44EE-B87F5D531772CF83_source.png"data-newsletterpromo-button-text="Sign Up"data-newsletterpromo-button-link="https:// origincode=2018_sciam_Article Promo_Newsletter Sign Up"name="article Body" itemprop="article Body" magazine The carbon clock is getting reset.Climate records from a Japanese lake are set to improve the accuracy of the dating technique, which could help to shed light on archaeological mysteries such as why Neanderthals became extinct.The deeper layers are older than the layers found at the top, which aids in determining the relative age of fossils found within the strata. Such index fossils must be distinctive, globally distributed, and occupy a short time range to be useful.Misleading results can occur if the index fossils are incorrectly dated.The problem, says Bronk Ramsey, is that tree rings provide a direct record that only goes as far back as about 14,000 years.Marine records, such as corals, have been used to push farther back in time, but these are less robust because levels of carbon-14 in the atmosphere and the ocean are not identical and tend shift with changes in ocean circulation.Carbon dating is used to work out the age of organic material — in effect, any living thing.The technique hinges on carbon-14, a radioactive isotope of the element that, unlike other more stable forms of carbon, decays away at a steady rate.
Paleontology seeks to map out how life evolved across geologic time.These rocks normally form relatively horizontal, parallel layers, with younger layers forming on top.If a fossil is found between two layers of rock whose ages are known, the fossil’s age is thought to be between those two known ages.Stratigraphy is the science of understanding the strata, or layers, that form the sedimentary record.Strata are differentiated from each other by their different colors or compositions and are exposed in cliffs, quarries, and river banks.