Survey (archaeology)
In archaeology, survey or field survey is a type of field research by which archaeologists (often landscape archaeologists) search for archaeological sites and collect information about the location, distribution and organization of past human cultures across a large area (e.g. typically in excess of one hectare, and often in excess of many km2).
Archaeologists conduct surveys to search for particular archaeological sites or kinds of sites, to detect patterns in the distribution of material culture over regions, to make generalizations or test hypotheses about past cultures, and to assess the risks that development projects will have adverse impacts on archaeological heritage.
Surveys can be a practical way to decide whether or not to carry out an excavation (as a way of recording the basic details of a possible site), but may also be ends in themselves, as they produce important information about past human activities in a regional context.
[1] Consideration should be given to the nature of the landscape (vegetation coverage, existing settlement or industry, soil depth, climate) before a range of techniques is selected to be applied within an appropriate overarching method.
This can be valuable in determining the cost of an excavation - if there is a build-up of several meters of soil above the layers the archaeologist is interested in, the price will obviously be much higher than if artifacts are found only centimeters below ground.
However, variations in artifact visibility related to topography, vegetation, and soil character, not to mention the imperfect detection abilities of human observers, bring into question the very concept of complete coverage.
An extensive survey, on the other hand, is characterised by a low-resolution approach over targets within a study area (sometimes including hundreds of km²).
Conventionally, fieldwalking in grids or along lines called transects has formed the backbone of archaeological survey fieldwork, at least where visibility is fairly good.
A single researcher or team will walk slowly through the target area looking for artifacts or other archaeological indicators on the surface, often recording aspects of the environment at the time.
Intensive arable agriculture on hilltops will first expose and then pulverize artifacts such as pottery and even chipped stone (typically flint, chert or obsidian) flakes.
[6][7] Conversely, the plateau and upper scarp or valley side soils will move down slope, forming a deep seal over low-lying archaeological deposits, rendering them inaccessible to surface survey.
Recording the position and attributes of archaeological features has been expedited by customizable portable computing interfaces or mobile Geographical Information Systems (GIS).
[8] Databases containing existing regional archaeological data as well as other landscape GIS layers such as soils, vegetation, modern features, and development plans can be loaded on a mobile GIS for referencing, for sampling purposes, and for groundtruth updating directly in the field, resulting a more informed archaeological survey process.
Humus and fallen leaves in forested areas, silt on alluvial fans, or turf in built-up neighbourhoods may render near-surface artifacts and sites invisible even at short distances.
Because of the high costs involved in some kinds of surveys, it is often helpful to use "predictive modelling" to narrow down the search for archaeological materials.
Geophysical instruments can detect buried archaeological features when their electrical or magnetic properties contrast measurably with their surroundings.
The geophysical methods most commonly applied to archaeology are magnetometers, electrical resistance meters, ground-penetrating radar (GPR) and electromagnetic (EM) conductivity.
These methods provide excellent resolution of many types of archaeological features, and are capable of high sample density surveys of very large areas and of operating under a wide range of conditions.
Appropriate instrumentation, field survey design, and data processing are essential for success, and must be adapted to the unique geology and archaeological record of each site.
The types of questions that archaeologist often ask of survey data include: what is the evidence for first occupation of an area; when was this area occupied; how are sites distributed; where are sites located; what evidence is there for a settlement hierarchy; what sites are contemporary with each other; how has the modern landscape interfered with the visibility of archaeological remains; what sorts of activities can be recognized (e.g., dwellings, tombs, field systems); how many people lived in this area at any given time or how did population density change over time; why did people choose to live where they did; how has the landscape changed over time; what changes in settlement patterns have there been?
