An Introduction to Aerial Archaeology
You can be sure that an aerial photograph of a potential archaeological site is worth more than a thousand words to an archaeologist and they can thank O.G.S. Crawford, known as the inventor of the scientific use of aerial archaeology, for that. Using a "distant view" of an archaeological site has been utilized since the last century and is considered an old tool for prospecting. In World War I, German military pilots took aerial photographs of ruined towns and cities in Sinai, this being the first time that airplanes were used for archaeology. There are only a few photographs from earlier times that are in existence today, the most famous being Stonehenge in 1906.
Besides actual photographs of the prospective sites an archaeologist will also use thermal images, satellite images and airborne radar images to accumulate data. Gravesites, ruins and settlements produce specific compositions that are easier to identify from higher vantage points. If you were to stand on a prospective site you cannot see the patterns of natural occurrences, infrastructure etc. whereas, from a higher vantage point patterns become clearer and more understandable. Archaeological sites appear on the ground exterior and depend on the conditions of preservation. An Aerial Archaeologist may look at:
Shadow Marks - which are the light and shadow contrasts
Soil Marks - which are the tone differences in soil
Crop Marks - which are differences in the height and color in cultivated fields
Aerial Archaeologists locate, document and map prospective archaeological sites in order to preserve, protect and extract data. Their main application that is utilized is an archaeological survey of the site. Basically, there are two types of sites. The first being structures that rise above the earth's surface such as castles and ruins. These are studied using the shadow marks and are labeled "Shadow Mark Sites". The second types are those that have been leveled by infrastructure, agriculture and/or natural occurrences. These are studied using the soil marks and/or crop marks and are labeled "Soil/Crop Mark Sites".
In today's society with the increase in infrastructure, the destruction of potential archaeological sites is increasing. Therefore, the need for aerial archaeological prospecting has growing. Because of this, the focus of an Aerial Archaeologist has become prevention of the demolition of potential ruins. Another threat is erosion which accelerates in highly vegetated areas. Limitations can also include climate, the time of day that the photograph was taken, vegetation, obstructions and soil types.
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