Proving carbon dating wrong up river dating profile
"The radiocarbon dating technique may significantly underestimate the age of sediment for samples older than 30,000 years,” said the authors of the report from the Chinese Academy of Sciences and Germany’s Leibniz Institute for Applied Geophysics.“Thus it is necessary to pay [special] attention when using such old carbon data for palaeoclimatic or archaeological interpretations," they added.But the method had one major flaw: it didn’t account for changes in the proportion of radioactive and non-radioactive carbon in the environment; and if these had changed, the estimate would most likely be wrong.Many events can affect the levels of carbon-14 in the atmosphere, such as the burning of fossil fuel or the detonation of an atom bomb.This leaves out aquatic creatures, since their carbon might (for example) come from dissolved carbonate rock.That causes a dating problem with any animal that eats seafood. After about ten half-lives, there's very little C14 left.Acetone is sometimes used while extracting fossils, because it dissolves dirt.In short, unless you have evidence to the contrary, you should assume that most of the carbon in a fossil is from contamination, and is not originally part of the fossil. The nuclear tests of the 1950's created a lot of C14.
But as soon as the creature dies it stops absorbing these and sheds any trace of carbon-14 at a decay rate of 50 per cent every 5,700 years.
Prior to that, they had to depend on more rudimentary and imprecise methods, such as counting the number of rings on a cross-section of tree trunk.
This all changed in the 1940s when US chemist Willard Libby discovered that carbon-14, a radioactive isotope, could be used to date organic compounds.
But the new study suggests that the sediment might be over 80,000 years old, possibly formed during an ice age.
"The carbon-14-based mega-lake hypothesis was even incorporated into modelling work to interpret regional climate dynamics,” the paper reported.
By comparing results from the two methods, they found that carbon dating became unreliable beyond a range of 30,000 years.