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| The main application of aerial archaeology is archaeological survey. Archaeological sites are increasingly threatened with destruction. The main threat is the erosion, accelerated in areas with intensive agriculture, that is removing the archaeological layers centimeter by centimeter. There is also a growing destruction of archaeological sites due to the exploitation of our resources, like gravel and sand mining, and due to the construction of railways, roads or big industrial areas. Time and again this results in the complete destruction of archaeological sites. We can assume that a quite high percentage of them was still unknown, leaving irretrievable holes in the archaeological landscape. Therefore, we have to perform what may be called "preventive prospecting", which means, that we have to try to detect and document sites before their destruction. |
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HERZOGBIRBAUM The circular ditch is part of a Bronze age cemetery. Unfortunately, the site is almost completely eroded. You can see this at the ditch, which is already partly vanished.
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Another kind of survey is performed in the course of research projects, where archaeological sites and their contemporary surroundings or the development of landscapes are investigated. Aerial archaeology can be used to look into those areas to show relationships between settlements, graveyards, former field boundaries, roads and topographical situation.
For example some sites, such as the large circular ditched enclosures of the middle neolithic, can only be detected cost effectively using aerial archaeology. In this case, field walking, would only provide us with the dating. All the other prospection techniques, as well as excavations, cannot be used to detect this kind of sites, although most of them will be used for closer investigations on these sites afterwards. In the distribution map of middle neolithic circular ditches of Lower Austria, 98% of the sites were detected using aerial archaeology. The other two percent were found incidentally during large scale rescue excavations.
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DISTRIBUTION MAP The map shows the distribution of middle neolithic circular ditch systems in Lower Austria. Almost all of them were detected from aerial photographs.
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Discovering a site is mostly not enough. If it comes to closer investigations, the archaeologist should try to get as much information about the buried structures as possible in advance. For this reason, the features, that can be detected in the photographs have to be mapped.
Especially, if a site is photographed several times in different years and at different seasons, more and more details can be drawn from the soil. Using photogrammetrical tools, these can be plotted together like peaces of a puzzle. The result is a map of the archaeological landscape, that gives important information to the archaeologist. Using the mappings as a basis, he can choose areas, where closer prospection, like field walking or geophysics, has to be done. Especially in combination with these other prospection techniques, the map becomes more and more detailed. In that way, the archaeologist gets a powerful tool, which helps him to pose exact questions and to investigate these with carefully directed excavations, thus saving time and money.
During excavations, aerial photographs help to show the excavated area within its landscape; these photographs are especially wanted for lectures, exhibitions and publications. They can also be helpful to relocate excavations after some decades, when the coordinates have got lost.
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GARS/THUNAU The excavations at the fortified settlement of the Slavic period in Gars are photographed almost every year. This picture, from 1989, shows the area of the early Slavic graveyard.
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Furthermore, aerial photographs are an important tool to visualize a site within its landscape. Including the surrounding landscape, contexts become clearer, especially for colleagues who are not familiar with the site itself. Additionally, applying photogrammetrical techniques, contour lines and digital terrain models can be measured and interpolated and digital orthophotos are computed. These facilities help visualizing your site and its underlying topography.
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TRAISMAUER - Lower Austria Todays center of Traismauer is built over the ruins of Roman "Augustianis", a military Camp at the Limes. The original plan can still be revealed by aerial photographs. © Flugbildkompanie Langenlebarn
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