Passage IV

Radiocarbon Dating,Tree Rings, and the Distant Past

[1]

Radiocarbon dating, developed by Willard F. Libby in the 1940s, seemed to offer archaeologists a definitive method for determining the age of artifacts. The method for archaeologists to date artifacts was based on the amount of radioactive carbon 14 found in organic matter such as wood, bones, and shells. [A] A living organism absorbs carbon 14 until the moment it dies, at which point the amount of carbon 14 in an organism starts to decay to nitrogen 14. Carbon 14's half-life (47) is 5,730 years. Therefore, as long as even the smallest amount of carbon 14 is present; radiocarbon dating can date an artifact by calculating its ratio of carbon 14 to nitrogen 14. [B]

[2]

However, questions were arisen at the time about the method's accuracy. The data from radiocarbon dating conflicted with long-established theories archaeologists had developed on the basis of Egyptian dynastic records. [C]

[3]

Even though Libby won the Nobel Prize in 1960, experts realizing, they needed another method to corroborate Libby's findings. They turned to a much older dating method; dendrochronology, the use of tree rings for mapping intervals of time. [D] Working together, experts in both methods dated thousands of wood samples from bristlecone pines, some of which share habitats with Douglas firs and piñon pines. When plotted on a graph called a calibration curve, these data with calendar dates provided a method for correlating radiocarbon dates.

[4]

The radiocarbon dates, now verified as accurate, overturned conventional thinking in archaeology and proved that dating methods based on Egyptian records were inaccurate. (57) Some stone monuments in Europe, for example, were found to be up to 800 years older than the Egyptian and Greek structures that had supposedly inspired them. These findings lead to the establishment of different facts and things about many places, such as Stonehenge and the stone temples of Malta.