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Absolute dating

Dates are expressed in absolute terms, that is in specific units of measurement such as days, years, centuries, or millennia. For example, the village was inhabited between AD 1400 and 1650. Absolute dates may be expressed with a standard deviation (see Radiocarbon dating.) Absolute dating and relative dating are contrasting concepts.


The study of ancient soils in an archeological context.


Portable objects that are used, modified, or created by human activity.


A collection of artifacts.


An artifact's physical property, such as the material(s) from which the artifact is made, its size, shape, function, and decoration.


Covering an archeological site with fill to stabilize and preserve it.


The process of describing and recording an artifact's many attributes.


Artifacts that are modeled or molded from clay and then made durable by firing.


Material remains that are excavated or removed during a survey, excavation, or other study of a prehistoric or historic resource, and associated records that are prepared or assembled in connection with the survey, excavation or other study.

Compliance work

Archeology undertaken to comply with requirements mandated by law. Often compliance refers to work done to satisfy requirements of Section 106 of the National Historic Preservation Act of 1966, as amended, or comparable state laws.


Measures taken to prolong the life of an object or document and its associated data as long as possible in its original form. May involve chemical stabilization or physical strengthening.


The arrangement or position of artifacts, ecofacts, and features within the soil matrix.


Relative dating of objects based on consistencies in stratigraphy between parts of a site or different sites, and objects or strata with a known relative chronology.


The long-term, professional management and care of objects, associated records, and reports.


Debris produced during stone tool manufacture.


Event occurring during or after the formation of a site that may cause strata to disappear in one area of the site and reappear farther along at a different distance from the surface. Distortion could result from processes such as landfilling, dumping, a landslide or other earth movement.


Also referred to as tree-ring dating, this absolute dating technique uses annual growth rings of trees from a single region to compare and match sequences of growth rings to determine that date when the tree was first cut down. Dendrochronology is also used to calibrate radiocarbon dates.


Event that changes the contexts of materials within a site, moving and mixing materials from and between strata. Some causes of disturbance are farming, heavy construction, rodent burrowing, and natural forces such as floods.


Natural remains, such as those of wild and domesticated animals and plants, that are found in the archeological record.


Nonportable elements such as hearths, postholes, soil stains and architectural elements such as walls and trenches.


Suspending soil samples in liquid, usually water, to recover tiny materials.


Science by which archeologists incorporate geomorphological studies to gain an understanding of what earlier landforms were like, where sites potentially may be located, and insights regarding prehistoric raw material availability, site formation processes, and landscape history.

Geologic dating

Relative dating technique used by geologists to develop dates for various geological stages by relating them to other climactic and geologic events.


The science that studies the general configuration of the earth's surface, specifically the study of the classification, description, nature, origin, and development of present landforms and their relationships to underlying structures, and the history of geologic changes as recorded by these surface features.


Abbreviation for Geographic Information System, an analytic tool used to create a computerized, layered composite of spatial information about an area.


Abbreviation for the Global Positioning System, a “constellation” of satellites that orbit the Earth and make it possible for people with ground receivers to pinpoint their geographic location. GPS allows archeologists to determine location coordinates in the field. Archeological sites and their environments can be mapped quickly and accurately using GPS to measure control points.


Text-aided archeology that studies that portion of human history that begins with the appearance of written records and continues until today.

Historical science

Sciences such as geology, evolutionary biology and archeology that deal with past events that no longer can be directly observed or replicated, although the evidence they left behind can be studied to reconstruct what took place.


Ties and uniformity across space at a single point in time. In archeology, a horizon is a pattern characterized by widespread distribution of a complex of cultural traits that lasts a relatively short time. Factors that might create the pattern of a horizon would include a rapid military conquest or effective religious mission. Horizon and tradition are contrasting concepts.

In situ

The position in which an archeological object is first uncovered during an excavation or survey.


Elements that break the continuity of a stratum such as stones, tree roots, walls, wells and post holes.

Law of Superposition

This law holds that, under normal circumstances, deeper layers of soil, sediment, or rock are older than those above them.

Material culture

Elements of the physical environment that people have modified through cultural behavior. Tangible material culture may reveal information about intangible cultural elements such as social practices and ideology.

Mean ceramic dating

Technique used in historical archeology to date sites based on the average age of recovered ceramics. A mean ceramic date (MCD) provides a weighted average of manufacturing dates and does not indicate a range of occupation.


A trash deposit, located either in a contained feature such as a pit, or spread over the ground surface. The latter is referred to as a sheet midden.

Obsidian hydration

Absolute dating technique that measures the microscopic amount of water absorbed on freshly broken obsidian surfaces. The principle behind obsidian hydration dating is simple—the longer the artifact surface has been exposed, the thicker the hydration band will be—but its application requires careful analysis of absorption rates for different obsidian sources. Obsidian hydration can indicate an artifact's age if the datable surfaces tested are only those exposed by deliberate flintknapping, rather than by accidental breakage.


The analysis and interpretation of plant remains from archeological sites in order to understand the past interactions between human populations and plants (Thomas 1998:325).


A plant microfossil composed of silica.

Pipe stem dating

Technique used in historical archeology to date sites based on the statistical analysis of English clay smoking pipe bore widths.

Primary context

The soil layer and location in which an artifact, ecofact or feature was originally deposited or constructed.


The precise location on a site where artifacts were recovered.

Radiocarbon dating

Absolute dating technique based on the knowledge that living organisms build up organic carbon. When the organism dies, the carbon 14 (C14) atoms disintegrate at a known rate, with a half-life of 5,700 years. It is possible to calculate the date of an organic object by measuring the amount of C14 left in the sample. Because the concentration of radiocarbon in the atmosphere has varied considerably over time, radiocarbon dates as far back as 7,000 years may be corrected by calibrating them against accurate dates from radiocarbon-dated tree rings and developing a master correction curve (see Dendrochronology).

Relative dating

Dates are expressed in relation to one another, for instance, earlier, later, more recent, and so forth. For example, the habitation of the east end of the site is older than the one on the west end. Relative and absolute dating are contrasting concepts.

Research design

A plan in which the objectives of an archeological investigation are described and justified. It states research questions and describes methods and techniques to be used to identify, recover, study and store associated archeological materials.


Methods for identifying portions of an archeological site or resource area to be examioned. Sampling methods vary according to each research design.


Relative dating technique whereby artifacts are ordered temporally based on the assumption that cultural styles (fads) change and that the popularity of a particular style or decoration can be associated with a certain time period. The fattest part of the cluster is the central part of the fad (Thomas 1998:246).


A fragment of a ceramic artifact.


Location where there is evidence for the human past. A site is often a spatial cluster of artifacts, features, or ecofacts that can be quite sparse.

Social context

Interpretations of an artifact's technical production and use, its value to the people who used it, and perhaps how and if the object symbolized those peoples' ideology.


Condition when pieces of material have come off an artifact.


Preserving an archeological site or artifact by supporting or strengthening it to reduce the possibility of deterioration.

Stratum (plural strata)

A soil layer, visually separable from other layers by a distinct change in color, texture, or other characteristic.


Analysis of sequences of layered, or stratified, deposits. Like geological exposures, archeological sites usually contain stratified layers, some of them the results of human activity, like house building, and others from natural phenomena like rain and wind.


Abbreviation for shovel test pit, a type of subsurface probe. Archeologists place shovel test pits at systematic or random patterns in an area being investigated. Each pit is approximately one foot in diameter and extends deep enough to penetrate sterile subsoil.

Terminus post quem (TPQ) dating

The date after which a stratum, feature, or artifact must have been deposited. The TPQ is determined by the most recent date. A 1962 penny, for example, indicates that the feature in which it was found dates to after 1962.


Absolute dating technique used for rocks, minerals and ceramics. It is based on the fact that almost all natural minerals are thermoluminescent—they emit light when heated. Energy absorbed from ionizing radiation frees electrons to move through the crystal lattice and some are trapped at imperfections. In the lab, ceramic samples are heated, releasing the trapped electrons and producing light that is measured to fix a date.


A pattern of long persistence of cultural traits in a restricted geographical area. Traditions not only suggest a strong degree of conservatism, but a stable pattern of permanent settlement that allows such developments to take place relatively undisturbed. Tradition and horizon are contrasting concepts.


Arrangement of artifacts into idealized categories or types.

Zooarcheology (or archeozoology)

The study of faunal (animal) remains from archeological sites.

Sections of this Glossary were adapted from:

Childs, S. Terry and Eileen P. Corcoran
2000 Managing Archeological Collections. Archeology Program, National Park Service, Washington, DC.

Deetz, James
1996 In Small Things Forgotten: An Archaeology of Early American Life, Revised Edition. Doubleday, New York.

Thomas, David Hurst
1998 Archaeology, Third Edition. Harcourt Brace College Publishers, Fort Worth.