The radioactive carbon isotope is no longer replenished; it only decays.
Scientists have calculated the rate at which C14 decays.
The number of dates from the two projects was only large enough to allow for statistical comparisons for the pyramids of Djoser, Khufu, Khafre, and Menkaure. First, there are significant discrepancies between the 19 dates for Khufu and Khafre, but not for Djoser and Menkaure.
Second, the 1995 dates vary widely even for a single monument.
We then compared our results with the mid-point dates of the kings to whom the monuments belonged (Cambridge Ancient History, 3rd ed.).
The average radiocarbon dates were 374 years earlier than expected.
The earliest experiments in radiocarbon dating were done on ancient material from Egypt. Libby’s team obtained acacia wood from the 3rd Dynasty Step Pyramid of Djoser to test a hypothesis they had developed.
Interest in Egyptian chronology is widespread in both popular and scholarly circles.
Ancient baking left deposits of ash and charcoal, which are very useful for dating.
The 1995 set of radiocarbon dates tended to be 100 to 200 years older than the dates, which was about 200 years younger than our 1984 dates.
Four of the Senwosret II dates were only off by 30, 24, 14, and three years.
Significantly, the older date was on charcoal (see “old-wood problem” below).
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Scientists have developed calibration techniques to adjust for these fluctuations.