Radiocarbon dating belfast
But levels of carbon-14 in the atmosphere vary from year to year, so scientists need to calibrate their estimates using long-running records of radiocarbon levels.
The shells of marine creatures provide one such record, but it represents the level of carbon-14 in the oceans, which does not exactly reflect the amount in the atmosphere.
Cave formations like stalactites and stalagmites, which get their carbon-14 from groundwater, run into the same problem.
Trees provide more accurate readings, since they get their carbon-14 directly from the atmosphere and they lay new visible rings every year.
But tree ring data only go back 13,000 years, and thus cannot be used to calibrate older dates.
“The hope has always been that we’d find records that we could use for the whole period of radiocarbon dating,” said Bronk Ramsey. Due to yearly changes in the lake’s surrounding vegetation, different types of organic material settled on its bottom in summer and winter.
The data will allow archaeologists to better gauge the age of their samples and estimate the timing of important events such as the extinction of Neanderthals or the spread of modern humans through Europe."Up to now we had no upstanding medieval fabric surviving in our city - now we have a round tower." Belfast Telegraph By Jonathan Bell The constitutional position of Northern Ireland is "none of the EU's business," Brexit negotiator Michel Barnier has said as he bids to set the record straight on the backstop - the main sticking point in...