An archaeological survey (also called archaeological reconnaissance or prospecting) helps archaeologists locate sites. Surveys also allow us to collect information about the distribution of these sites across a large area in order to study the social, political, economic interactions and connections between these same sites at a regional level. On a smaller scale, the survey will help us identify interesting features within an already known archaeological site.
Numerous surveying methods are available to archaeologists and each method has different results. Depending on their research goals, archaeologists will select the most appropriate method of survey. Some of these archaeological survey methods are defined below.
Foot Survey (also known as “fieldwalking” or “transect”)
The foot survey is rather simple. Archaeologists will map out a grid in the area they wish to survey. A survey team of several people will be asked to walk slowly on a line of the grid, looking for artefacts or other evidence of human activities. Fieldwalking works best on plowed ground because the turned soil will regularly bring artefacts to the surface. It also works on flat ground that has not been cultivated since the historical period the archaeologists are interested in. Fieldwalking in a dense forest or jungle is quite different because buildings and artefacts may be covered by vegetation and are virtually invisible. In this case, the survey team will look for unnatural changes in the vegetation and landscape to decide if a building is hidden under the vegetation.
Aerial photography is used to survey an area by taking photographs from the air. Cameras will be mounted on a kite, a hot-air balloon, an airplane or some other kind of flying vehicle. Aerial photos give archaeologists a good overview of an entire site (or a large portion of it). Architectural features, even covered by layers of sand or buried under a crop field, are actually visible from the air (as are the ones already cleared and visible on the ground). It is the difference in the terrain that is visible, not the covered building themselves. Archaeologists will use aerial photography to identify these features from the air because the difference in the terrain is very difficult to identify from the surface.
Geophysical survey can be used to find features within an already known archaeological site. It allows archaeologists to locate underground features, when there is very little evidence on the surface. This procedure is time consuming and is not used on a large scale. Surveyors will use machines, such as a magnetometer or a resistivity meter, and will walk a grid in a predetermined area. The result will be some kind of underground map of the surveyed area.