How do archeologists know where to look for sites?
A Geographic Information System (GIS) is a powerful analytic tool that can make regional data more useful to archeologists. A GIS is used to create a computerized layer cake of spatial information about an area, each layer representing a single spatial attribute. The layers are all entered with the same coordinate system so that they are georeferenced, for example, compared with one another. The different layers can be things like roads, streams, soils, elevation, etc. Information is represented in the form of points (such as archeological sites), lines (such as roads or steams), or polygons (such as a soils or a geology map.)
GPS data from Fort Washington Park in Maryland. Red points are gun positions, the brown line is the parapet (Historic Preservation Services, NPS)
The Global Positioning System (GPS) is a technology that greatly benefits archeology because it helps show exactly where a site is located. The GPS is a constellation of 24 well-spaced satellites that orbit the Earth and make it possible for people with ground receivers to pinpoint their geographic location. A portable GPS receiver obtains signals from the satellites to calculate the user's position anywhere on earth. The locational accuracy is anywhere from 1 to 100 meters depending on the type of equipment used. GPS allows archeologists to determine exact location coordinates in the field. Archeologists can map sites and their environments can be mapped quickly and accurately using GPS to measure control points. Based on the set of on-site readings that the GPS receiver generates, archeologists can locate sites as single point coordinates, or as areas, or as corridors with many points. GPS data can also be transferred into GIS databases, making the GIS even more precise and powerful.
Shipwrecks, Satellites, and Computers: An Underwater Inventory of Our National Parks
Read about a systematic survey of submerged archeological resources at Dry Tortugas National Park, which used background research, predictive models and GIS.
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Resources Mapping and Geographic Information Systems (GIS)
Learn about National Park Service programs for locating and mapping cultural resources using advanced computer technologies.