Scientists discover secret of more precise carbon dating

December 30, 2012

Scientists discover secret of more precise carbon dating

An international team of researchers says that a Japanese lake offers great prospects for carbon dating.

A number of sediment cores and plant fossils from Japan’s Lake Suigetsu will provide scientists with more accurate benchmarks for carbon dating the oldest objects, according to a statement from Oxford University’s Radiocarbon Accelerator Unit.

Professor Christopher Ramsey, his doctoral student Richard Staff and chemist Dr Fiona Brock worked with the NERC facility at East Kilbride, Scotland, and Groningen in the Netherlands to extract the lake’s radiocarbon record as part of an international research team led by Professor Takeshi Nakagawa of Newcastle University, whose main focus has been studying cores for clues about past climate and environmental change.

Although the ultimate goals of the larger research group are to examine climate change, the data gathered by the team may illuminate many mysteries of science. Certainly, the Radiocarbon Accelerator Unit has been able to take advantage of the large amounts of data necessary for Professor Nakagawa’s exploration of climate change as a means of refining the complex method of carbon dating.

The process of radiocarbon dating relies on the known rate at which radioactive isotopes decay and measuring the remaining amount of radiocarbon within a sample. This ratio provides scientists with a precise estimate of how old a certain artifact might be. Complications in these calculations arrive from how the initial radiocarbon in the environment varies from year to year and from one part of the global carbon cycle to another.

Therefore, carbon dating often has a wide range, which could stretch anywhere from a couple hundred to a few thousand years. To help resolve this, the ratios of each unknown artifact are compared against other known artifacts and means of measurement in order to more accurately pinpoint the date.

“In most cases the radiocarbon levels deduced from marine and other records have not been too far wrong. However, having a truly terrestrial record gives us better resolution and confidence in radiocarbon dating,” said Professor Ramsey.

Previously, the longest and most important radiocarbon dates have come from marine sediments of cave formations. Now, however, even these dates have been corrected and a more direct record of radiocarbon from the atmosphere will assist scientists in narrowing the range of radiocarbon dating.

Using what Oxford University calls beautifully preserved layers of sediment from the bottom of Lake Suigetsu, where organic material has lain undisturbed for tens of thousands of years, scientists have been able to narrow down the accuracy of carbon dating the oldest artifacts.

“This record will not result in major revisions of dates. But, for example in prehistoric archaeology, there will be small shifts in chronology in the order of hundreds of years,” said Professor Ramsey.

Researchers typically use a composite records called IntCal to identify the ages of objects, according to their radiocarbon measurements. Researchers are likely to incorporate data from Lake Suigetsu into the latest iteration of IntCal.


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