Carbon dating or date
When a plant or animal is alive, it constantly replenishes trace amounts of radiocarbon in its tissues.But once it dies, no more fresh radiocarbon is absorbed, and what’s left starts to decay.At Warratyi rock shelter in the Flinders Ranges, South Australia, which shows signs of the oldest human occupation of the country’s arid interior, the oldest sample – a fragment of emu eggshell – has been radiocarbon dated to 49,000 years with reasonable confidence.“Unlike bone or charcoal, carbon preserved in eggshell is very stably locked in and unlikely to have been contaminated,” says Nigel Spooner, a physicist at the University of Adelaide in Australia who specialises in dating techniques.See also, on this website, articles on the ages of the geologic periods (Ages), radiometric dating (Radiometric dating), the reliability of radiometric methods (Reliability), a "time machine" for studying the distant past (Time machine) and the "uniformitarian" assumption and how it relates to evolution and the age of the earth (Uniformitarian).
So along with radiocarbon dating, they use a technique known as optically stimulated luminescence (OSL) dating.
Once samples are older than around 40,000 years, though, amounts of radiocarbon remaining are very small and difficult to measure.
Then, only exceptionally well-preserved, pristine samples can provide reliable dates.
Also, at least one of these dates comes from a hide that had been soaked in glycerin, rendering the date invalid.
These and numerous other claimed anomalies in radiocarbon dating are explained in detail in Mark Isaak's book [Isaak2007, pg. In short, while like any other method of scientific investigation, radiocarbon dating is subject to anomalies and misuse, when used correctly in accordance with well-established procedures and calibration schemes, the method is a very reliable means of dating relatively "recent" artifacts.