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. The surveys 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), but may also be ends in themselves, as they produce important information about past human activities in a regional context. A common role of a field survey is in assessment of the potential archaeological significance of places where development is proposed. This is usually connected to construction work and road building. The assessment determines whether the area of development impact is likely to contain significant archaeological resources and makes recommendations as to whether the archaeological remains can be avoided or an excavation is necessary before development work can commence. Archaeologists use a variety of tools when carrying out surveys, including GIS, GPS, remote sensing, geophysical survey and aerial photography. Research and planning Survey work is conducted for a variety of reasons, some of which are motivated by threats to the preservation of archaeological material. These threats may include proposed land development or risks associated with processes such as decay or erosion. Surveys can also be conducted in the absence of threat as part of a research program or conservation efforts. Prior to engaging in fieldwork, desk-based assessments will likely take place, during which, written, visual, and electronic information is gathered for the purpose of evaluating and developing a plan for future fieldwork. Consideration should be given to the nature of the landscape (vegetation coverage, existing settlement or industry, soil depth, climate) before a range