Geoarchives as sources for reconstructing landscape changes in the hinterland of the Roman metropolis Pompeiopolis in northern Anatolia (Turkey)
The aim of the project is the reconstruction of connections between Roman urbanization and landscape change in the immediate vicinity (hinterland) of the Roman metropolis Pompeiopolis in Paphlagonia (northern Anatolia, Turkey). Since 2006, Pompeiopolis has been investigated through an interdisciplinary international research project. A supraregional classification and evaluation of the findings has been carried out since 2014 by the Bamberg Chair of Archaeology of the Roman Provinces. While archaeological research in Pompeiopolis has so far concentrated on the discovery of urban finds in order to capture the dimensions and cultural consequences of Roman urbanization in the region, the focus of geoarchaeological research is on the study of the hinterland especially to the north and northwest of the city hill of Pompeiopolis. The aim is to clarify for what purpose and to what extent the landscape in the immediate vicinity of the city was included in the urban development.
It can be assumed that the hinterland was infrastructurally reinforced by the Romans and, above all, was made arable and then used for the agricultural supply of the steadily growing urban population. Presumably, the Romans completely reorganized the preexisting rural infrastructural and agricultural systems, operated by the local population. This reorganization must have resulted in a significant change in the natural environment, e.g. by the clearance of woodland opening land for agriculture and pastoralism. The intensive cultivation and use of the open land by humans and animals in turn must have caused a strong use of the soil over time and thus also increased processes of the soil erosion.
To examine this hypothesis, the investigation of geoarchives such as soils and sediments (especially colluvial layers) is a suitable tool. In the course of landscape investigations these types of archives are to be mapped, sampled and analyzed to understand the processes of soil formation, erosion and sedimentation that determine the agricultural potential of the area. The investigation of the genesis of palaeo-soils and colluvial layers on the basis of horizon and layer boundaries as well as the age determination of these archives thus allow for a reconstruction of different soil formation phases and erosion/sedimentation cycles. In the context of the results of the archaeological excavations, a temporal classification of a possible change of the hinterland in the centuries of Roman urbanization will be derived.
The field campaigns in August 2015 and 2016 focused on geoarchaeological survey and fieldwork in the northern and northwestern hinterland of Pompeiopolis. During an earlier, short stay in the summer of 2014, a number of sites were already selected as suitable geoarchives. Fig. 1 shows a suitable location in a sink at about 600 m distance (as the crow flies) north of the town hill. This site was the starting point for surveying work using GPS. The partly steep surrounding slopes represent the catchment area for removal and accumulation of soil material at the site of the soil sondage.
Nowadays, the surrounding slopes are used intensively for arable farming and pasture management and have a very good soil quality (pers. Komm.N. Köskeroğlu, Agricultural Office Taşköprü). There is also a water source in the immediate vicinity (see Fig. 1). All of these factors speak for a possible agricultural use of the area even in the past. Therefore, this site was selected for detailed pedological prospection.
At the topographically lowest point of the terrain, soil material could be cored down to 2 m soil depth by means of the soil auger Edelman (Fig. 2). Exemplary, the present type of soil is a colluvisol whose individual horizons could be further differentiated on the spot by means of parameters such as soil color and grain size distribution. The profile is characterized by the sequence of the following soil horizons:
Ap (0 - 30 cm): Plough horizon: recent, agronomically used topsoil;
M1 (30 - 65 cm): most recent colluvium; very loose texture, soil texture sandy-loamy;
M2 (65 - 100 cm): older colluvium; more humic than M1; charcoal fragments; soil texture clayey sand;
M3 (100 - 180 cm): oldest colluvium; less humic than M2; increasing content of coarse soil components (diameter> 2 mm); charcoal fragments; soil texture clayey sand;
Cv (180 - 200 cm): transitional horizon of weathered parent material; high soil moisture, soil texture loamy clay.
From selected soil horizons cored at different sites, mixed samples were taken for further laboratory analyzes (wet-sifting, soil chemical analyzes). In terms of the age of the geoarchives, radiocarbon datings of the charcoal fragments from various colluvial layers will be performed. Moreover, determinations of the type of wood for the reconstruction of the former vegetation cover are made on these fragments. A synopsis of the geoarchaeological results will be published in the proceedings of the international conference "Contextualizing Pompeiopolis: Urban Development in Roman Anatolia from a Comparative Perspective" in 2018 .