Archaeology radiometric dating

10-Mar-2019 08:21

Shell may succumb to isotopic exchange if it interacts with carbon from percolating ground acids or recrystallization when shell aragonite transforms to calcite and involves the exchange of modern calcite.The surrounding environment can also influence radiocarbon ages.Alone, or in concert, these factors can lead to inaccuracies and misinterpretations by archaeologists without proper investigation of the potential problems associated with sampling and dating.

By comparing the amount of carbon 14 remaining in a sample with a modern standard, we can determine when the organism died, as for example, when a shellfish was collected or a tree cut down.In his process, an object is placed in a vacuum chamber and a supercritical fluid—a hybrid gas/liquid—is applied as a solvent (as in dry cleaning).Next, Rowe passes plasma—an "electrically excited ionized gas"—over the artifact, which selectively strips carbon from the sample.Desmond Clark (1979:7) observed that without radiocarbon dating "we would still be foundering in a sea of imprecisions sometime bred of inspired guesswork but more often of imaginative speculation." And as Colin Renfrew (1973) aptly noted over 30 years ago, the "Radiocarbon Revolution" transformed how archaeologists could interpret the past and track cultural changes through a period in human history where we see among other things the massive migration of peoples settling virtually every major region of the world, the transition from hunting and gathering to more intensive forms of food production, and the rise of city-states.However, as with any dating technique there are limits to the kinds of things that can be satisfactorily dated, levels of precision and accuracy, age range constraints, and different levels of susceptibility to contamination.

By comparing the amount of carbon 14 remaining in a sample with a modern standard, we can determine when the organism died, as for example, when a shellfish was collected or a tree cut down.

In his process, an object is placed in a vacuum chamber and a supercritical fluid—a hybrid gas/liquid—is applied as a solvent (as in dry cleaning).

Next, Rowe passes plasma—an "electrically excited ionized gas"—over the artifact, which selectively strips carbon from the sample.

Desmond Clark (1979:7) observed that without radiocarbon dating "we would still be foundering in a sea of imprecisions sometime bred of inspired guesswork but more often of imaginative speculation." And as Colin Renfrew (1973) aptly noted over 30 years ago, the "Radiocarbon Revolution" transformed how archaeologists could interpret the past and track cultural changes through a period in human history where we see among other things the massive migration of peoples settling virtually every major region of the world, the transition from hunting and gathering to more intensive forms of food production, and the rise of city-states.

However, as with any dating technique there are limits to the kinds of things that can be satisfactorily dated, levels of precision and accuracy, age range constraints, and different levels of susceptibility to contamination.

Radiocarbon dating is especially good for determining the age of sites occupied within the last 26,000 years or so (but has the potential for sites over 50,000), can be used on carbon-based materials (organic or inorganic), and can be accurate to within ±30-50 years.