The people of ancient Ireland snubbed their local gold in favor of more exotic, mystical gold found across the sea, new research shows. Scientists had long assumed that the gold that people in Ireland used during the early Bronze Age, about 4, years ago, came from nearby mineral-rich mountains. But now, extremely sensitive chemical analyses have revealed that the gold had been extracted from an area farther away, across the Irish Sea, in what's now southwestern Britain. This is the oldest gold work in Ireland, said Christopher Standish, lead author of the new study and a research fellow at the University of Southampton in the United Kingdom. Dating the gold artifacts, such as embossed gold armlets and gold oval plaques, can be tricky because the artifacts are often found isolated from one another, he said. Standish and his colleagues analyzed the lead isotopes in the gold artifacts, and compared the values to lead isotopes measured in potential sources of the gold, to determine their origin.
Radiocarbon dating: radioactive carbon decays to nitrogen with a half-life of years. In dead material, the decayed 14C is not replaced and its concentration in the object decreases slowly. To obtain a truly absolute chronology, corrections must be made, provided by measurements on samples of know age. The most suitable types of sample for radiocarbon dating are charcoal and well-preserved wood, although leather, cloth, paper, peat, shell and bone can also be used.
Love-hungry teenagers and archaeologists agree: dating is hard. But while the difficulties of single life may be intractable, the challenge of determining the age of prehistoric artifacts and fossils is greatly aided by measuring certain radioactive isotopes. Until this century, relative dating was the only technique for identifying the age of a truly ancient object.