image/svg+xml9XIV/1/2023INTERDISCIPLINARIA ARCHAEOLOGICANATURAL SCIENCES IN ARCHAEOLOGYhomepage: http://www.iansa.euGeophysical Survey and Changes in the Use of the Cultural LandscapeRoman Křivánek1*, Jan Tirpák21Institute of Archaeology, Academy of Sciences of the Czech Republic, Prague, Department of Information Sources and Landscape Archaeology, Letenská 4, 118 01, Prague 1, Czech Republic2Constantine the Philosopher University in Nitra, Faculty of Natural Sciences, Trieda Andreja Hlinku 603/1, 949 74 Nitra, Slovakia1. IntroductionNon-destructive geophysical methods are used primarily for the targeted detection, identifcation or verifcation of particular archaeological features and/or activities as well as entire sites. The choice of a suitable geophysical method, or a combination of several methods, is based on the given prospecting conditions as well as the requirements for distinguishing specifc archaeological features and situations. More, or also less, anticipated results are then most often presented to archaeologists in the form of two-dimensional maps of the measured physical parameter changes (in some cases vertical or horizontal sections or three-dimensional images), the aim being the best possible depiction of the sought or verifed archaeological situation. However, other archaeological contexts and possibly other situations may also be detected in the actual data and displayed results. While many of these correspond to various intentionally-sought relics of anthropogenic activities (archaeological situations), still others may refect diferent (sometimes former, but more usually later, modern and recent) anthropogenic activities that are seen as disruptive from the archaeologist’s point of view, as well as many changes in the land use or natural conditions of a site. The result of any (archaeo-) geophysical prospecting is in fact the sum of all these changes, with the heterogeneity of the measured data still increasing in the conditions of multicultural situations and the repeatedly-changed terrain of archaeological sites. In this respect there is great similarity with the explanation of the cultural landscape in terms of a palimpsest – as used in aerial archaeology (see, for example, Crawford, 1953; Cowley and Gilmour, 2005; Johnson, Ouimet, 2018; Kostyrko and Kiarszys, 2019). From the perspective of our feld experience, this is refected both in the magnetometer or electromagnetic data – and in Volume XIV ● Issue 1/2023 ● Pages 9–29*Corresponding author. E-mail: krivanek@arup.cas.czARTICLE INFOArticle history:Received: 3rdMay 2021Accepted: 8thJune 2022DOI: surveyland use changemagnetometryresistivity measurementground penetrating radarditch enclosurehillfortsacral architectureABSTRACTThe results of detailed and large-scale geophysical measurements in archaeology have been steadily increasing for years. The growth in measured data has also increased the need for processing and interpretation; in archaeology, this primarily means the archaeological interpretation of the measured data. However, the information contained in geophysical data includes a substantial volume or area of data of varying size or thickness of some diferent natural or modern anthropogenic origin (beyond archaeological interest). Like the archaeological situations themselves, these must also be identifed and demarcated. The presented article consists of a wide range of case studies in which the result of a specifc applied geophysical method includes both the desired interpretations of archaeological features and the diferentiation and warning of other anomalies, the origin of which may or may not be unambiguous or related to the post-deposition processes of archaeological features. The purpose of selecting several diferent examples of results in our paper is to point out that there are many more consequences of anthropogenic activity hidden beneath the surface of the terrain of the contemporary cultural landscape than just those that archaeologists have in their viewfnder. Other anomalies in specifc environments may be of natural origin or related to various geological, pedological or hydrological changes in a site’s natural environment. This should be dealt with by the alternative diferentiation of anomalies of various probable origins; the interpretive descriptions, diagrams or maps should not just focus strictly on the anticipated subsurface relics of the archaeological features and situations, as these are not there alone.
image/svg+xmlIANSA 2023 ● XIV/1 ● 9–29Roman Křivánek, Jan Tirpák: Geophysical Survey and Changes in the Use of the Cultural Landscape10another way in the result of the resistivity measurement or radar. Only some of these manifestations can be reliably distinguished as expressions of certain archaeological situations, but additional evidence of anthropogenic activities usually makes the results very difcult to read and frequently leads to ambiguous interpretations. In short, there are many subsurface and surface traces of anthropogenic activities in our intensively-exploited cultural landscape.2. ObjectivesThe main objective here is above all to draw the attention of archaeological readers (archaeologists and also archaeologists working with geophysical instruments and interpreting geophysical data) to the fact that the variability of the results of geophysical measurements depends not only on the number of subsurface archaeological situations, but increasingly on the extent and intensity (for an archaeological site) of subsequent (later) anthropogenic activities and the potency of changes to the landscape. While even these can be documented today, they also need to be intentionally monitored in the geophysical results of many examined archaeological sites in various environmental conditions (Kvamme, 2003; Campana, 2009; De Smedt et al., 2017; Cuenca-García et al., 2018; Křivánek 2019b). Using selected examples of geophysical measurements supplemented by the relative temporal interpretation of the origin of identifed situations (Figure 1), we illustrate the diversity of measured data and the very diferent sources of various anomalies that are a refection of the numerous changes and superpositions in the archaeological landscape. The four selected examples are based on the results of magnetometer measurements, with two of the examples being based on the results of geoelectric resistivity measurements and the other two examples using the separate results of radar measurements. Despite the fact these are diferent geophysical prospecting methods (in terms of principle, method of measurement and monitoring of physical properties), we can observe the infuence of changes in the cultural landscape in all the mentioned examples of results. Landscape changes also infuence the interpretation possibilities of the geophysical data in their various extent and form. On the other hand, the methodological diferences of the chosen geophysical methods also depend on the archaeological situations and the individual survey questions resolved at specifc sites. These are therefore explicitly mentioned in each individual example.3. Examples3.1 Magnetometer measurementEmployed apparatus: fve-channel fuxgate Magneto-arch gradiometer, Sensys (Germany), measurement density: 0.5×0.2 m, sensors FMG650B (gradient length 0.65 m), precision of results <0.2nT, positioning of data in relative coordinates (points of measured grid system 50×50 m georeferenced by GPS).