ARCHAEOLOGICAL SURVEY
Monte Alban archeological site
A modern archaeological project often begins with a
survey. Regional survey is the attempt to systematically locate previously unknown sites in a region. Site survey is the attempt to systematically locate features of interest, such as houses and
middens, within a site. Each of these two goals may be accomplished with largely the same methods.
Survey was not widely practiced in the early days of archaeology. Cultural historians and prior researchers were usually content with discovering the locations of monumental sites from the local populace, and excavating only the plainly visible features there.
Gordon Willey pioneered the technique of regional settlement pattern survey in 1949 in the
Viru Valley of coastal
Peru, and survey of all levels became prominent with the rise of processual archaeology some years later.
Survey work has many benefits if performed as a preliminary exercise to, or even in place of, excavation. It requires relatively little time and expense, because it does not require processing large volumes of soil to search out artifacts. (Nevertheless, surveying a large region or site can be expensive, so archaeologists often employ
sampling methods.) It avoids ethical issues (of particular concern to descendant peoples) associated with destroying a site through excavation. It is the only way to gather some forms of information, such as
settlement patterns and settlement structure. Survey data are commonly assembled into
maps, which may show surface features and/or artefact distribution.
The simplest survey technique is surface survey. It involves combing an area, usually on foot but sometimes with the use of mechanised transport, to search for features or artefacts visible on the surface. Surface survey cannot detect sites or features that are completely buried under earth, or overgrown with vegetation. Surface survey may also include mini-excavation techniques such as
augers,
corers, and
shovel test pits.
Aerial survey is conducted using
cameras attached to
aircraft,
balloons, or even
kites. A bird's-eye view is useful for quick mapping of large or complex sites. Aerial imaging can also detect many things not visible from the surface.
Plants growing above a stone structure, such as a wall, will develop more slowly, while those above other types of features (such as
middens) may develop more rapidly. Photographs of ripening
grain, which changes colour rapidly at maturation, have revealed buried structures with great precision. Aerial survey also employs
infrared, ground-penetrating
radar wavelengths, and
thermography.
Geophysical survey is the most effective way to see beneath the ground.
Magnetometers detect minute deviations in the
Earth's magnetic field caused by
iron artefacts,
kilns, some types of
stone structures, and even ditches and middens. Devices that measure the
electrical resistivity of the soil are also widely used. Most soils are moist below the surface, which gives them a relatively low resistivity. Features such as hard-packed floors or concentrations of stone have a higher resistivity.
Although some archaeologists consider the use of
metal detectors to be tantamount to treasure hunting, others deem them an effective tool in archaeological surveying. Examples of formal archaeological use of metal detectors include musketball distribution analysis on
English Civil War battlefields, metal distribution analysis prior to excavation of a nineteenth century ship wreck, and service cable location during evaluation. Metal detectorists have also contributed to the archaeological record where they have made detailed records of their results and refrained from raising artifacts from their archaeological context. In the UK, metal detectorists have been solicited for involvement in the
Portable Antiquities Scheme.
