Until the 1960s archaeological expeditions were mostly concerned with underground excavation. Since then, excavators have turned to less intrusive and cost effective methods for recovering data from the archaeological record. The technique known as Archaeological Survey complements traditional subsurface excavation and has become a pre-requisite to site excavation.
A Simple Technique
This simple method recognises that much of the data about the past can be gleaned by perusing the overlying ground and in particular any exposed landscape. Before preparations are made for the removal of earth from a proposed digging site a visual examination of the ground is undertaken to look for potential buried walls, buildings, or other substantial features. This is achieved by walking over the site once it has been mapped into grids. Commonly called field walking, the surveyors need keen eyes and a good imagination. A small dip in the ground could be a filled in well or an ancient midden. Everything is noted.
The degree of accuracy that is requested by the survey director will determine how much area is covered in a days work. If surveyors are asked to look for potsherds and other artefacts as well as record the geology of the site then many hours careful observation will be necessary.
The surface survey technique does not destroy the site to be investigated. The fact that nothing is removed provides the ability to revisit the site time and time again until it is deemed exhausted of surface information.
There are two primary purposes for using surface survey. Firstly, it is the most important method of confirming whether a proposed site is archaeologically suitable for conducting a full excavation. Many large expeditions have been launched at great expense only to have them yield very little data. Surface survey can avoid costly mistakes. Secondly, the collected data from a simple surface survey can reveal critical information about the way that past cultures used the natural geology around them. Did they farm it? Did they have heavy industry or areas of production? Roadways such as trade and travel routes that cross the landscape will also help to better understand civilisations that once lived there.
Artefacts such as potsherds are often widely scattered over the surface of a site and surveyors collect many examples. The study of these remains by pottery experts can indicate past activities. However, the surface survey archaeology needs to satisfy itself about he process that first scattered them. This can be both difficult and complex.
The science of studying landforms to determine their origin including both the imposition of human and natural forces to shape them is called geomorphology. The geomorphologist can greatly assist the archaeologist when attempting to read the data collected from a field walkover. Grand cataclysmic events such as massive earthquakes and altered sea levels right down to localised flooding or slow erosion processes, can be overlayed onto the survey map by the geomorphologist to better determine whether surface artefacts originally belonged where they were located or if they have been delivered there by other means.
Surface survey as an archaeological method of information collection, although apparently too simple to sound like a science, has now become firmly embedded as a fundamental data collection technique in its own right. Artefacts can be studied, sketched and photographed all in situ without the invasive destruction of the area.