Surveying
| Archaeological field survey is the methodological process to collect information about the location, distribution and organisation of past human cultures across a large area (e.g. typically in excess of one ha, and quite often in excess of many sq. km). It may be: (a) intrusive or non-intrusive, depending on the needs of the survey team (and the risk of destroying archaeological evidence if intrusive methods are used) and; (b) extensive or intensive depending on the types of research questions being asked of the landscape in question. 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) and may also be ends in themselves, as they produce important information about past human activities in a regional context. Archaeologists use a variety of tools in survey, including GIS, GPS, remote sensing, geophysical survey and aerial photography. Research and planning A field survey is usually the result of a long period of research and planning. The process will normally start with the notion that an area is worth further investigation, or that a site requires excavation (or that it should at least be recorded in some way). Rationale There are several reasons that an area may be considered to be worth surveying. In no particular order, they are: * Artifacts found: Locals have picked up artifacts, sometimes found in the local museum but more often in private homes or old buildings such as churches, and it is unclear where they are coming from. * Literary sources: Old literary sources, in some cases ancient Roman or Greek texts, have provided archaeologists with clues about settlement locations that have not been archaeologically documented. Sometimes the texts may be quite recent; a book on local history that mentions an interesting area. * Oral sources: In many locations, local stories contain some hint of a greater past, and there is often some truth to them. It is not uncommon for someone to remember that a grandfather who used to walk the hills around a town as a shepherd used to talk about columns from an old temple, without having actually seen these themselves. * Local knowledge: In many cases, locals actually know where to find something that is of interest to archaeologists. They may not have reported it, either because it's simply a part of their world, or because they fear intrusions on their land. * Previous surveys: In some places, a survey was carried out in the past, and is recorded in an obscure academic journal. It may have been disregarded at the time, but more recent technologies and finds from other sites might cast a different light on it. * Previous excavations: Excavations carried out before the middle of the 20th century are notoriously poorly documented. They were also often carried out in a way that left much of the evidence the modern-day archaeologist is looking for behind, preferring to carry away only fine pottery, jewelry and statues. * Lack of knowledge: Many areas of the world have little known about the nature and organisation of past human activity at the regional level (even when one or more 'sites' may be known from an area, often little is known about the wider distribution of contemporary settlements, and how settlement patterns may change over time). Archaeological field survey is the primary tool for discovering information about previously uninvestigated areas. Permissions It is usually a simple matter to gain permission to perform a survey, especially a non-intrusive one. If the area is privately owned, the local laws may or may not require the landowners' co-operation. Permission for an intrusive form of survey may be more difficult to acquire, due to the fear of destroying evidence. Extensive vs. intensive survey Archaeological field survey can be divided into two types: intensive survey and extensive survey. The former is characterised by the complete or near-complete coverage of the survey area at a high-resolution, most often by having teams of survey archaeologists walk in a systematic way (e.g. in transects) over parcels of the landscape in question, documenting archaeological data such as lithics, ceramics and/or building remains. Extensive survey, on the other hand, is characterised by a low-resolution approach in which (e.g.) only samples of a larger study area (often in excess of several sq km) are visited. Extensive surveys are quite often designed to target the identification of archaeological sites across a large area, whereas intensive surveys are designed to provide a more comprehensive picture of the location of sites and the nature of off-site data (e.g. field systems, isolated finds, etc.). Intensive survey is the more costly, timely, and ultimately informative of the two approaches, although extensive survey can provide important information about previously unknown areas. Field walk (transects) An important part of the survey is normally the field walk (or transect). The common way to perform it is to construct a grid, place the survey team in a line and then walk slowly through the area looking for artifacts or other indications. This works best on either plowed ground or surfaces with little vegetation. On ploughed surfaces, as the soil is turned regularly artifacts will move to the top. Erosion and soil loss on uncultivated and lightly vegetated soil (e.g., in semi-arid environments) may cause artifacts to also 'rise' to the surface. Modern technology such as GPS has made survery recording much easier, as positions can be taken well within the limits necessary for survey work. In some areas, the field walk is quite different. When searching in dense jungle, buildings may be covered by vegetation, and are therefore virtually invisible even at short distances. The team will then need to look for unnatural changes in the vegetation and landscape to decide if a building is hidden below the vegetation. Narrowing it down At this stage, the problem is often that one knows the approximate distribution of archaeological material, but it needs to be more precisely mapped. During the field walk, the members of the team are likely to miss minor pieces of artifacts hidden in vegetation. However, if they are all trained to look for the same thing, it is likely that they will miss the same amount of artifacts, and the results of the survey can therefore still be used to draw a map of find frequencies within the grid system. This might in turn make it possible to identify an archaeological site. Geophysics Geophysics offers a non-destructive way to see beneath the soil. Geophysics is the study of the Earth’s properties and it uses the Earth’s own magnetism and electricity to show what is below the ground without having to dig a hole. This is sometimes called "geophysical survey" or "remote sensing".
Ground Penetrating Radar Aerial Photography
Aerial photos are one of the most useful tools that an archaeologist has for finding archaeological sites. They show what archaeology might be underneath a piece of land. They are photographs taken from a plane and they come in 2 types these are called oblique photos and vertical photos. Aerial photographs are usually called "APs".
2. Vertical means that they are taken from directly above the site;
What affects the aerial photos? * The time of day and the time of year affect an aerial photograph and how good it is, in other words, what it shows up on the photo. |
