Absolute Date

Any date where a year or range of years can be applied to a site or artifact. As opposed to a relative date where only a chronological order can be established.

accelerator mass spectrometry (AMS)    

A variety of radiocarbon dating. In conventional radiocar- bon dating, the amount of carbon-14 left in a sample is measured indirectly by the amount of radioactivity the sample gives off. In AMS dating, the amount of carbon-14 left in a sample is measured directly by an actual count of atoms.

Activity Area

A place where an activity or group of ac- tivities were carried out in the past.The activity area is transformed into an archaeological feature by the loss or discard of material items used in the activity— stone toolmaking, cooking, butchering, burial—that was carried out there.

Archaeomagnitism

Orientation of the earth’s magnetic field can become fixed in relatively recent cultural de- posits like the sediments in a canal or the clay in bricks lining a kiln.The date of a site can be determined where that orientation points to a location of magnetic north already fixed in space and time along a master curve. 

Argon/Argon Dating

Absolute dating method based on the decay of radioactive potassium to stable argon gas. Argon-argon dating is an updated and more accurate version of potassium-argon dating. Potassium is abun- dant in rock and is usually applied in the dating of rock strata. Because of the long half-life of radioactive potassium, there is no upper chronological limit to the application of the technique. 

Artificial Selection

The process used in the domestica- tion and refinement of plants and animals whereby human beings select which members of a species will live and produce offspring. Humans make such deci- sions on the basis of their needs or desires concerning the form or behavior of the species: plants that pro- duce larger seeds; animals that produce woollier coats; animals that produce more milk.

Association

Term relating to the spatial relationships among archaeological artifacts, ecofacts, and features. Objects found in proximity to each other are said to be in association.    

C3 Pathway

The photosynthetic process employed by most trees. In the C3 pathway, a radioactive isotope of carbon, 13C, is differentially filtered out.

C4 Pathway

The photosynthetic process employed by most grasses and sedges. In the C4 pathway, a radioac- tive isotope of carbon, C, is more readily used than in plants that follow the C3 pathway    

Cache

 A stash of stuff placed away for safe keeping by ancient people.When the archaeologist is lucky, a cache was not returned to in the past and what- ever was stored therein was not retrieved. A cache becomes the equivalent of an unintentional time capsule, providing a cluster of artifacts representing a single time period. 

Calibration Curve

Curve resulting from the graphing of dendrochronologically derived dates for an exten- sive series of tree rings and the carbon dates deter- mined for each of those same rings.

Carbon Dating

Radiometric dating technique based on the decay of a radioactive isotope of carbon: 14C or radiocarbon. Carbon dating can be applied to virtu- ally anything that was once part of a living organism within a range from about 50,000 to 500 years ago. Also called radiocarbon dating.    

Carbon Isotope Analysis

Coprolites

Fossilized feces, useful in the reconstruction of an ancient animal’s diet. 

Cranial Structure

Lines of connection between cranial bones. Sutures appear as squiggly lines on both the interior and exterior surfaces of the skull. Sutures progressively disappear with age and can be used to provide a general estimate for age at death.

Deciduous Dentition

Baby teeth. The teeth that are shed like the leaves of deciduous trees.


Dendrochronology

Tree-ring dating. By placing a tree section found at an archaeological site within a master sequence of tree-ring widths through time, the age of the tree (when it died or was cut down) can be determined and associated with the site at which it was found.

Diaphysis

The shaft of a long bone. On either end of the diaphysis there is an epiphysis.

Ecofact

Element found in archaeological contexts that exhibit human activity, but were not made by people and so are not, strictly speaking, artifacts. Burned wood in a fireplace, butchered animal bone in a trash pit, and charred seeds or nuts in a midden are all ecofacts. 

Ejecta

All the material thrown out of a volcano during an eruption.

Epiphyseal Fusion

The epiphyses of each long bone join to the diaphyses during the process of physical maturation.The age of death of a juvenile individual can be assessed by reference to the degree of epiphy- seal fusion exhibited. 

epiphysis (pl.—epiphyses)
 

The endcaps of the long bones.The epiphyses join at the ends of the diaphysis of each long bone.

Experimental Replication

The reproduction, under lab- oratory conditions, of facsimiles of archaeological arti- facts. Process employed to analyze ancient technology. 

Faunal Assemblage

The animal bones found at a site and the species represented by those bones.

Feature

Combination of artifacts and/or ecofacts at a site, reflecting a location where some human activity took place. Features include fireplaces, middens, burials, cooking hearths, activity areas, and buildings. Features are also defined as nonportable, complex artifacts.    

Foraminifera

Microorganisms used in the study of ancient environments. By measuring the ratio of 16O:18O in foraminifera fossils, the amount of the earth’s surface covered in ice at any given point of time can be indirectly determined. 

Ground-Penetrating Radar (GPR)

A noninvasive technique to investigate the subsurface. An electromagnetic pulse is passed through the soil. The pulse encounters objects or differently compacted soil layers and bounces a signal back to a receiver. The signal can be interpreted and imaged, revealing buried walls, earth- works, or other cultural features. 

Half-Life

Measurement of the amount of time it takes for half of the radioactive isotope in a given sample to decay into a stable form. The half-life of radiocarbon, for example, is 5,730 years while that of radioactive potassium is 1.3 billion years.

Hypothesis

A proposed explanation for some phenomenon. A hypothesis may be derived initially from empirical observation of the phenomenon; the process called induction. Hypotheses must be tested; predictions are deduced of what new data must be found if the hypothesis is to be supported. When data are found that contradict these predictions, the hypothesis is rejected or modified.

Isotope

Variety of an element’s atomic form. Isotopes are distinguished by the number of neutrons in their atomic nuclei. Some isotopes are unstable and decay into other forms. These are said to be radioactive. Some radioactive isotopes can be used in dating pale- ontological or archaeological material.

K/Ar Dating

Potassium/argon dating. The half-life of radioactive potassium has been measured to be 1.3 billion years. Since potassium is an abundant element in the earth’s crust and since argon collects in rock at a fixed rate as a result of the decay of radioactive potassium, this technique is widely applicable.

Luminescence Dating

Determining the age of an object by releasing as light the energy it has accumu- lated during its existence.The amount of light it emits in this process is directly proportional to its age. Light (optically stimulated luminescence) or heat (thermo- luminescence) can be used to release this energy.