3 Dating Limitations and Chronological Interpretation Free Online FlashCards

What does relative chronology establish?

Relative chronology establishes which events came before or after others, often using the order of undisturbed layers.

What does radiocarbon dating directly estimate?

Radiocarbon dating estimates when a carbon-bearing sample stopped exchanging carbon with its environment; it does not directly date a layer or activity.

When can a sample date approximate an archaeological event?

A sample date can approximate an event when the sample is securely associated with it, formed or deposited at about the same time, and remained undisturbed.

What is the old-wood effect?

The old-wood effect occurs when charcoal from long-lived wood dates to the wood’s earlier growth, potentially decades or centuries before it was burned.

What is residual material in an archaeological layer?

Residual material is older material redeposited in a later layer, so its radiocarbon date may predate that layer’s formation.

What is intrusive material?

Intrusive material is younger material moved downward into an older layer, for example by roots or burrowing animals.

How can modern-carbon contamination affect an old sample?

Modern carbon added to an old sample, such as from rootlets, can make the sample appear younger.

How can aquatic reservoir effects shift radiocarbon ages?

Marine or some freshwater carbon can contain less radiocarbon than contemporary atmospheric carbon, making organisms that used it appear older.

What does BP mean in a conventional radiocarbon age?

A conventional radiocarbon age is usually reported in years BP, meaning before AD 1950; it is not yet a calendar date.

How is a radiocarbon measurement calibrated to calendar time?

Calibration compares a radiocarbon measurement with records of past radiocarbon levels, using a curve appropriate to the sample, such as IntCal or Marine20.

What form does a calibrated radiocarbon result take?

A calibrated result is a probability distribution, often reported as one or more calendar-date ranges with associated probabilities.

Why can one radiocarbon measurement yield several calendar ranges?

Bends or relatively flat sections of a calibration curve can produce several separate calendar ranges; reporting only a midpoint hides this uncertainty.