Fouling feature
Cropmark (Engl. Cropmark ) is a technical term of Archeology , which (usually the different growth and maturity of plant crops ) called on hidden in the ground archaeological findings. The vegetation feature is used to prospect archaeological sites. This is understood to be a non-destructive exploration of sites that are already known or that have been rediscovered through prospecting. In recent times, this method has been used primarily in aerial photography archeology .
Origin of the vegetation feature
Humidity differences
A growth feature is triggered by differences in humidity, which affect the growth of the plant in the critical periods of the growth cycle. Grains in particular, especially barley (but also oats , wheat and rye ), react very sensitively to changes in the subsoil. Other plants such as grass or potatoes, on the other hand, are very insensitive. For this reason, vegetation features in grain fields are known.
The existing moisture contrast is decisive for a good development of the growth characteristics. Generally very moist or impermeable soils (e.g. loam soils) form hardly any visible growth marks. In the case of very dry or water-permeable soils (e.g. sandy and chalky soils), however, the effect can be drastic.
The plant spacing is important for the visibility of the hidden ground monument. Grain is planted very closely and therefore has a high point density (comparable to the image resolution of a scanner or the grain of a photograph). Maize is planted at such a large distance from the plant that for this reason alone it can no longer be used as an indicator of vegetation features.
Dry summers prove to be beneficial for observing the growth characteristics.
Positive growth feature
A positive growth feature can be observed through depressions such as trenches, post pits , storage pits , waste pits, etc. These areas, which are gradually filled with organic material, lead to a better and more humid breeding ground. The plant can develop stronger roots. This results in higher growth and later ripening with a longer, stronger green color.
Negative growth feature
A negative fouling feature can appear over hidden wall foundations or floors. Because of the underground obstacle, the roots do not get to the deeper moisture. The smaller thickness of the nutrient medium leads to the plants drying out more easily. The development of the root system is considerably impaired. Lower growth and premature ripening with yellow coloration can be observed. Negative vegetation features are often traced even more prominently through shadows.
Use of the vegetation features
As early as 1586, the English archaeologist William Camden discovered vegetation features in a cornfield and interpreted them as archaeological sites. Since the beginning of antiquity research, vegetation features have been part of the archaeological prospecting methods, i.e. for the localization and documentation of archaeological sites - without excavation.
Usually an overall impression can only be gained from a bird's eye view , which allows an interpretation of the feature. For this reason, vegetation features are generally discovered, documented and observed today through aerial photo archeology . For a good documentation of a vegetation feature it is necessary to observe it both at different times of the year and over several years.
Other methods of botanical prospecting
In addition to the vegetation features, the methods of botanical prospection also include the mapping of the vegetation. This method is used to localize desertions (abandoned settlements) and makes use of the fact that overgrown medicinal, garden and cultivated plants are preserved for a long time and can thus serve as indicators for former settlement areas.
literature
- Lore Kutschera : Root atlas of Central European arable weeds and cultivated plants . Frankfurt / Main: DLG-Verlag 1960
- Irwin Scollar: Methods of Modern Air Archeology . In: Barthel Hrouda (ed.): Methods of archeology . Munich 1978. ISBN 3-406-06699-2
- David Raoul Wilson: Air photo interpretation for archaeologists . London, 2nd Edition 2000.
- R. Lasaponara, N. Masini: Detection of archaeological crop marks by using satellite QuickBird multispectral imagery . In: Journal of Archaeological Science, 34 (2), 214-221.