The archaeological site of Sagalassos (Turkey): exploring the mysteries of the invisible layers using geophysical methods

The archaeological site of Sagalassos is a very important settlement located in a magnificent mountain landscape, 7km north from a village named Alasun (province of Burdur, south-west Turkey). Since 1990, the University of Leuven (Belgium) has carried out an interdisciplinary archaeological research program that studies >1000 years of uninterrupted human occupation in Sagalassos, concerning all historical aspects of daily life from architecture, to trade and its mechanisms and environmental conditions. The ancient Roman city is covered by layers of eroded soil that has preserved many secrets waiting to be revealed. A geophysical campaign was planned along the south facing terraces of the mountain slopes to highlight the structure of the city that remains covered in soil. Site conditions (high slope, high grass, several obstacles) and the need to investigate to depths greater than 20m influenced the choice of geophysical methods; we chose to use both passive and active electrical resistivity tomography. Three different areas, labelled Area 1, Area 2 and Area 3, were investigated, with results revealing information about the location, depth, size and extent of buried archaeological features. Of particular interest is the presence of: (i) a deep depression in Area 1, thought to be a clay quarry; (ii) a number of tombs related to the Byzantine period in Area 2; and (iii) defensive walls in Area 3.