A shovel test pit (STP) is a standard method for Phase I of an archaeological survey. It is usually a part of the
Cultural Resources Management (CRM)
methodology
In its most common sense, methodology is the study of research methods. However, the term can also refer to the methods themselves or to the philosophical discussion of associated background assumptions. A method is a structured procedure for bri ...
and a popular form of rapid archaeological survey in the
United States of America
The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 states and a federal capital district, Washington, D.C. The 48 contiguo ...
and
Canada
Canada is a country in North America. Its Provinces and territories of Canada, ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, making it the world's List of coun ...
.
It designates a series of (c. 0.50 m or less) test holes, usually dug out by a
shovel (hence the name) in order to determine whether the soil contains any
cultural remains that are not visible on the surface. The soil is sifted or screened through 1/4" or 6 mm wire mesh to recover the artifacts.
STPs will often be laid out over the project area in a grid-like fashion or in a consistently spaced line, creating a fairly systematic survey.
Therefore, after the holes have been dug, one may map artifact densities over the project area, pinpointing the locations of possible sites where further investigation may be necessary. The
interval at which the STPs are placed varies considerably and, in CRM at least, is sometimes prescribed by
state regulations (in the
U.S.) or is determined by the conditions in the field. The usual space between two STPs is 10 m or more but it can be considerably less (e.g., 1 m). The current standards in the United States is 30m or less. The depth of an STP depends on the depth at which either the bedrock or the
sterile subsoil
Subsoil is the layer of soil under the topsoil on the surface of the ground. Like topsoil, it is composed of a variable mixture of small particles such as sand, silt and clay, but with a much lower percentage of organic matter and humus. The su ...
is found.
The form of STP may vary from region to region and even within regions by company/organization. Common forms include circular and square shaped. Circular STP often have cylindrical to "bullet" (i.e., cylinder with short inverted conical base) shaped profiles and range from 30 cm to 50 cm diameter. Square STPs are typically about 50 cm, but some locations prefer other sizes (e.g., 40 cm). Unusual and unusually ineffective variants include circular (30 to 50 cm diameter) STP with truncated conical profiles.
Depth of STP excavation also varies widely and is often dependent upon local soil types and expected maximum depth of sites. Typically this ranges from 30 cm to 1.0 m. A second factor is mechanical, in that excavation is limited by the tools and techniques used (i.e., shovel versus
trowel). Typically STP are excavated to a maximum average of 1.0 m, although it is possible to excavate somewhat deeper (1.25 to 1.5 m) dependent upon the excavator and the tools available. STP can be combined with other techniques and tools (augers, corers) to extend the maximum depth of effective testing beyond 1.5 m.
See also
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Archaeological excavation
In archaeology, excavation is the exposure, processing and recording of archaeological remains. An excavation site or "dig" is the area being studied. These locations range from one to several areas at a time during a project and can be condu ...
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Trial trenching
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Watching brief
References
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Methods in archaeology