SEAC: Geographic Information Systems
Spatial position is critical to understanding archeological resources. The location of an artifact within a site, the site in relation to other sites, or a site’s environmental setting all play a role in archeological interpretation. Location also plays a big part in determining archeological time – typically, the artifacts found deeper in a site are older than those found higher up.
In order for SEAC staff to assist parks with preserving and protecting cultural resources, we need to know where to find the sites. Also, information about which parts of a park have been surveyed and the methodology used help us plan for new projects. Until recently, that information was plotted on paper maps that were not very accurate and scattered among reports and field notes.
GIS (geospatial information systems) is a new and expanding technology that SEAC has embraced for tracking resources and survey. But GIS is much more versatile than the old paper maps because it can integrate information from many sources. Links to reports, photographs, and field records give us instant access to vital information. GIS map layers showing roads, trails, vegetation, soils, and terrain can be analyzed together to predict where archeological sites might be found or which sites are more vulnerable to climate change or recreational activities. We use GIS tools for project planning and creating maps for reports. Data from other technologies are employed in concert with GIS. The most important of these is the GPS equipment that records location data during fieldwork. The results of geophysical surveys can be added to GIS to enhance our understanding of archeological sites. SEAC’s GIS was started for the center’s staff, but recently we have developed online map viewers in order to share information with parks and the public.
GIS software can include links to non-spatial sources. At SEAC, we convert project reports to PDF format so that an archeologist sitting at a computer can select a survey area in the map and open the related report with a couple of clicks. For special projects, we can include photographs of the excavations and artifacts. We also integrate information from a database that contains information about archeological sites. Return To Top
The national parks of the Southeast Region cover thousands of square miles, so only a small fraction has been surveyed by archeologists. To plan for surveys that are both efficient and effective, we use GIS to predict where sites may be found. A variety of approaches are possible.
GIS analysis tools can find combinations of water and elevation that would have been suitable environments for humans in the past.
Overlaying high resolution elevation data and imagery in GIS reveals high ground that could have been a dry place to live in a marshy part of a park.
Historic maps show buildings, roads, farm fields, creek channels and more that are no longer visible, but which could remain underground as archeological features. With GIS software, the historic map can be aligned to features that still remain. The archeologist gets the GIS coordinates for the possible sites that appear on the historic map, and uses GPS equipment to navigate to the coordinates. Return To Top
GIS can be a “what-if” tool for planning a survey. A proposed trail and parking lot needed to be tested to ensure that construction wouldn’t disturb any archeological sites. GIS was used to generate positions for the archeological tests spaced every 20 meters, then the positions on steep slopes (light blue) were eliminated because we know that sites aren’t usually found on steep ground. Using the remaining number of tests, the archeologist could determine how many crew members would be needed to finish the work in a week.Return To Top
SEAC archeologists use GIS to make accurate maps for reports about field projects. A good map uses layers, colors, and symbols to convey spatial information about the sites that were found by a survey or to show the area covered by excavations. The map’s north arrow, scale, and legend provide the context. Return To Top
Professional quality Global Positioning System (GPS) equipment is an vital companion tool for GIS. Before starting fieldwork, the archeologist loads site locations from the GIS into the GPS unit, then uses the GPS to navigate to sites in the park. Also, the GPS is used to record the locations of excavations and any sites that are discovered. Back in the office, the newly collected GPS data are displayed in the GIS map and used to digitize the boundaries of the sites and survey. Return To Top
The digital results from geophysical surveys, which can show differences buried archeological features, can be viewed in GIS maps. In this example, ground penetrating radar (GPR) data revealed a pattern that turned out to be the foundation of a historic building. The two white rectangles show the locations of excavation units that were dug to confirm the GPR results. The foundation walls were digitized in GIS because the foundation is an archeological site. Return To Top
SEAC and parks need to work together to protect resources, so sharing the data that SEAC’s GIS Program develops is a good way to improve coordination. Because the data is stored on a server at SEAC, we use server and web technology to share information. We’re also starting online maps for the public. Of course, many archeological sites are considered sensitive, non-renewable resources, so the types of information that can be shared are limited, but still interesting. Explore the historic cemeteries of Mammoth Cave National Park.