5. Reconstructing the Past: Archaeology and Time

Diachronic

Concerned with the way in which something, especially language, has developed and evolved through time

Synchronic

Concerned with something, especially a language, as it exists at one point in time

Chronology

The study of time

Relative Dating

A way of dating that dates something relative to something else, ex. saying something is older than this, younger than that. Stratigraphy, cross-dating, seriation, fluorine dating, paleomagnetism are examples of this dating

Absolute Dating

A way of dating that provides a more or less exact date. Based on solar year, ex. Saying something is from 2000 years ago. Historical, radiocarbon dating, dendrochronology, potassium-argon, thermoluminescence, and OSL are examples of this dating

Stratigraphy

A type of relative dating that is based on the sequence of deposits in a geological layer. Layer cake. We can say some layers were accumulating at the same time because some layers are the same texture.

Super-position

Principle made by Nicolas Steno, says that the youngest layer is the layer on top, the oldest layer is the layer at the bottom.

Cross-dating

A type of relative dating that connects stratigraphy between different sites. Can be done with fossils too

Seriation

A type of relative dating that assumes change in form over time. ex. Phone screens get bigger, cameras get better, so a phone must be old if it has a small screen or worse camera.

Historical dating

A type of absolute dating, a variety of ways we can reckon time. Calendars (that’s not always in our calendar year system), king lists, coins with dates, time capsules, monumental inscriptions, etc.

Willard Libby

Person who invented the technique called radiocarbon dating in 1949.

Radiocarbon Dating

A type of absolute dating, it measures the amount of carbon isotope C14, it would decay at a constant rate and would help us determine how old something was. C14 has a half life of 5730 years. It can date up to 80,000 years ago. It can date wood, bone, shell, skin, etc.

Dendrochronology

A type of absolute dating, uses tree rings to calculate the year a tree was born. Discovered in 1910 and first applied to anthropology in the 1920s. Sequences can extend up to 6500 BC

Potassium Argon Dating

A type of absolute dating, very similar to radiocarbon dating. K-40 decays to Ar-40 at a known rate, has a half life of 1.3 billion years. Useful for dating volcanic areas. Useful from 300,000-several billion years

F-U-N Trio

A type of relative dating, fills in the gap from 80,000-300,000 years ago that C14 and K-A dating can’t date. Involves the replacement of nitrogen by fluorine and uranium in the bone.

Thermoluminescence

A type of absolute dating, uses ceramics and burnt stones and calculates its luminescence. We can figure out what time that object was heated at that certain degree.

Optically Stimulated Luminescence (OSL)

A type of absolute dating, quartz and feldspar within the soil layers are useful to measure dates, by measuring the luminescence signal emitted by these minerals.