Scientists Set a Date - 54,000 Years Ago; BOFFINS SEE INTO THE EARTH'S PAST WITH NEW CARBON TEST
Byline: ROBIN TURNER firstname.lastname@example.org
RESEARCH by Welsh scientists means carbon dating can now stretch back 54,000 years.
Mud built up over thousands of years on the floor of a Japanese lake has enabled the scientists to make significant improvements to the precision and accuracy of radiocarbon dating.
Radiocarbon dating has been a success for archaeologists since it was invented in the 1950s. It has been used to determine the age of Stonehenge and to test the age of the Turin Shroud. But it could previously only reach back 12,000 years.
The basic principle of radiocarbon dating is fairly simple. Plants and animals absorb trace amounts of radioactive carbon-14 from carbon dioxide (CO2) in the atmosphere while they are alive but stop doing so when they die.
The steady decay of carbon-14 from archaeological and geological samples ticks away like a clock, and the amount of radioactive carbon left in the sample gives an accurate indication of how old it is.
There is one major glitch in the approach, however. The amount of carbon-14 in the atmosphere varies with fluctuations in solar activity and Earth's magnetic field, and "raw" radiocarbon dates have to be corrected with "calibration" that takes these natural fluctuations into account.
Tree-ring segments from the Northern Hemisphere help with calibration, as do things like coral, because they accurately reflect carbon-14 levels in the atmosphere at certain time periods.
The problem meant radiocarbon dating could only accurately "look back" around 12,000 years or so.
Now, however, collaborative work by scientists at Aberystwyth University on the muddy floor of Lake Suigetsu in Japan, as reported in Science, the journal of the American Association for the Advancement of Science (AAAS), has provided a huge calibration resource which will help archaeologists go further back in time, possibly as much as 54,000 years.
Previous studies of Lake Suigetsu revealed sediment on the floor was made up of fine layers which were formed annually. …