742 
NON DESTRUCTIVE GEOPHYSICAL SURVEYES: 
ARCHAEOLOGICAL FEEDBACK 
M. Cim inale and D. Gallo 
Department of Geology and Geophysics, University of Bari, Campus Universitario 70125 Bari, Italy - marci@geo.uniba.it, 
danilo_ 13@libero. it 
KEY WORDS: Geophysics, Surveying, High resolution, Mapping, Detection, Anomaly, Feedback, Archaeology 
ABSTRACT: 
In this work are introduced three different magnetic surveys and a geoelectric one performed in Turkey and in Apulia (southern 
Italy). The geophysical prospection was required by the archaeologists to guide excavation programmes and to rescue a site destined 
to be partially destroyed. A cesium gradiometer magnetometer and a dipole-dipole array were used for collecting data. Despite the 
presence of perturbing contributions all the surveys had a remarkable archaeological feedback that largely satisfied archaeologists’ 
expectations. At the same time for the geophysicists arose the possibility to provide, in retrospect, complete information of the 
sources of signal (geometry, location in the space, composition, physics properties). This allowed to verify under best conditions, the 
results of the employed methodologies, the interpretative aspects, the techniques of elaboration and visualization of the data. Some 
detected anomalies were critically compared to the corresponding structures brought to the light by the following excavations. 
1. INTRODUCTION 
In the last 50 years geophysical techniques have been offering a 
relevant contribution for archeological research. The possibility 
to obtain quick information on buried archaeological structures 
in a non-destructive way constitutes a precious advantage for 
planning and optimizing excavations in already known sites. 
Moreover by opportunely integrating the information obtained 
with remotely sensed images, it is possible to offer a 
considerable help to the investigation and the location of those 
archaeological sites which are partially known and of those 
which have not been discovered yet (Ciminale and Ricchetti, 
1999). Finally, in many cases, geophysical survey proved to be 
essential for the knowledge and the study of those areas of 
archaeological interest which were bound to be extensively 
modified or even destroyed by modern development. 
Figure 1. Location of the surveyed archaeological sites. 
The four geophysical surveys discussed below, which were 
performed in Turkey and in Apulia (Figure 1), constitute 
meaningful examples of the effectiveness of the magnetic and 
electric methods in answering archaeologists’ demands. Despite 
the difficult environmental conditions it was possible to locate 
and recognize the archaeological structures. Digital Image 
Processing (DIP) was used to enhance visualization (Mather, 
1999) of the high resolution geophysical data making easier 
interpretation and identification of archaeological features. 
Each survey is presented explaining the archaeological context 
in which it was performed and its main purpose. The 
characteristics of the recorded signal are analyzed using the 
information derived from the excavations. The comparison 
between the highlighted anomalies and the recovered structures 
has outlined the good correspondence both in their mutual 
position and in the likeness of their shapes. 
2. THE MAGNETIC AND ELECTRIC SURVEYS 
The magnetic and the d.c. electric surveys are among the most 
largely employed methods in archaeological research (Scollar et 
al„ 1990). 
The first one is based on the analysis of the anomalies of the 
earth’s magnetic field, produced by the contrast of 
magnetization and/or of magnetic susceptibility between the 
bodies present in the subsoil (object of the research) and the 
material which englobes them. Fundamental aspect in the 
application of the magnetic method to the archaeological 
research is the high resolution with which the signal is recorded. 
Both the techniques of acquisition of data and instruments have 
been conceived to allow a survey with a very narrow sampling 
step in less time. The modern magnetometers are able to acquire 
up to 10 data s’ 1 , with a sensitivity of a picotesla (Becker, 1995). 
Therefore it is possible, by using proper field procedures, to 
detect also the highest frequencies of the magnetic signal, 
improving identification and location of the buried structures. 
However, magnetic data are very often affected by noisy 
contributions (due to systematic and non-systematic errors), 
which may degrade the magnetograms rendering the correct 
interpretation of the anomalies uncertain (Eder-Hinterleinter et 
al., 1996). It is essential for this reason to restore the real value 
and shape of anomalies before the interpretative phase. In 
favorable conditions objects of remarkable archaeological 
interest such as kilns, hearths, bricks, pottery, iron objects, 
etc..., endowed with an elevated remanent magnetization, can 
produce strong magnetic anomalies easily identifiable. 
With the d.c. electric method it is possible to detect with high 
sensitivity slight differences of electric resistivity between 
bodies inside the subsoil. The most useful technique for 
archaeological aims is a combination of sounding and profiling 
which delineates variations in resistivity across the vertical 
plane through the direction of the survey. Data can be visualized 
as electric pseudosections obtaining an immediate transversal 
view of the subsoil. This allows for an easy first estimate of the