Field survey

Systematic artefact surveys

 

 

Line walking and intra-site artefact pick-ups.

 

For the systematic artefact surveys, consisting of plots intensively surveyed with line-walking as well as extensively surveyed areas, three large sample zones were selected. These are systematically spaced at regular intervals across the ca. 80 km long Potenza valley. The selected areas cover the main landscape types of the region, between the mountains and the sea, generally coinciding respectively with the upper, middle and lower Potenza valley, and positioned in the vicinity of Roman towns and/or protohistoric centres. The sample area in the upper Potenza valley (extensive survey area: 17 km², intensive survey area: 3.2 km²) is positioned within the intra-montane basin of the Umbria-Marche Apennines. This fertile hilly plain around the narrow Potenza is dominated by the Bronze and Iron Age hilltop site of Monte Primo (1300 m). In Roman times, the basin was used as an important north-south connection between the Roman towns Camerinum (Camerino) and Matilica (Matelica). The middle Potenza valley is characterized by a moderately hilly landscape, formed by dorsal ridges and secondary valleys. The sample area (extensive survey area: 18.8 km²; intensive survey area: 3.7 km²) is situated east of two hill spurs, controlling the river passage. The Potenza is dominated here by the Monte Franco promontory and the Monte Pitino hilltop, both important Iron Age sites. The area north of the Potenza River probably belonged to the territory of municipium Trea. The latter was positioned on a dominant plateau immediately west of its successor, the medieval hilltop village Treia. Near Ricina (Villa Potenza), the hilly valley opens up into a large open plain, flanked by the Apennine dorsals. The third sample area is located along the coast (extensive survey area: 32.7 km², intensive survey area: 3.9 km²) and comprises the broad valley plain, delineated to the north by the Montarice hill ridge, another Bronze and Iron Age valley control site, and in the south by the hilltop on which present day Potenza Picena (235 m) is located. The Roman town Potentia is situated within this sample area, which enabled us to investigate the close relationship between the colony and its immediate hinterland. With the foundation in 184 B.C. of the coastal colony for Roman citizens Potentia (Livy XXXIX, 44, 10) the lower Potenza valley, and with it this whole area of northern Picenum entered its definitive phase of Romanisation and real urbanization.

For the general artefact surveys, conducted mainly between 2000 and 2005, a basic line-walking survey technique was chosen, in combination with on-site random walking after initial location and identification of relevant site scatters. Within the sample areas each field was considered to be one collection unit, defined by modern field boundaries and topographic breaks. Preference was given to ploughed fields surveyed at times of optimal visibility, and intervals of 5m were the standard. Much attention was given to off-site density, while regular site revisits (min. 15% of all identified sites) allowed for fine resolution interpretations. Nevertheless, some significant problems with site identification remained, if based only on the local surface evidence. Although systematic archaeological field survey using artefact pickups has proven to be the most effective tool for tracing occupation patterns, there are a number of factors hindering an optimal scan of the landscape. Firstly, processes of erosion and colluviation have significantly altered the landscape over time in some areas, covering or destroying sites, especially within the hilly segment of the Potenza landscape. Also the attested repositioning of the river Potenza during the medieval and post-medieval periods decreased visibility. Modern surface use, such as for housing, roads and commercial activities, and some types of vegetation, covered and partly destroyed some archaeological sites. Finally, site identification and especially dating for the Roman period relied heavily on the building materials connected with the settlements and on the chronological characterisation of the surface artefacts. Especially for the transitional phases, such as from later Iron Age to the Republican period, or from late Antiquity to the Early Middle Ages, there still is a lack of representative dating material. As the identification of site chronology is often primarily based on the presence of fine wares, absence of such diagnostic pottery can result in major problems for fine dating. During the second and third centuries C.E., for example, there is a hiatus between the end of terra sigillata and the start of massive imports of African red slip. In the northern and central Adriatic, the terra sigillata medio-adriatica subsequently replaced terra sigillata, but was apparently not distributed in large quantities in its initial phase of production. For the late Roman period, the most commonly studied dating agents are imported wares like African red slip, Late Roman C, African and eastern amphorae. The clear drop of African red slip imports around the mid fifth century AD, especially in the hinterland, causes problems for identifying site occupation. Regional pottery productions are far less abundant and are still understudied, making it very difficult to fully solve the problem. Part of the remedy came from the PVS-team’s study of some good stratigraphic contexts excavated in the recent past on Roman sites in the valley, and mostly from the new material evidence collected since 2007 during the new Ghent University excavations at Potentia.

Since 2002 and especially 2004 the team undertook also short campaigns of intensive grid walking on a series of large and complex sites, such as on the Roman town sites of Potentia, Trea and Ricina, and on some protohistoric centres (such as Montarice) where Roman occupation was also mapped carefully. Several types of grids were applied to these surveys (40x40 m, 20x20, 10x10 m blocks), while also different pick up strategies were experimented. These intensive field surveys were often carried out in close collaboration with the geomorphologic team, in order to take into account biases induced by physical processes at the sites, such as erosion and riverside sedimentation, while a close integration with data from remote sensing was pursued.

For each field a form is filled (form A) with data on the field‘s conditions, such as topography, land use, visibility, weather condition, soiltype, etc. For each concentration we mark information about its density, the concentration extend, etc. Furthermore, a description and a first opinion about the general date and the function of the site or isolated find is added. Afterwards, these standardized fieldforms get digitalized in the PVS–database.
Site density is expressed in terms of low, medium and high. Thereby, “low” means at most ten artefacts/m², a “medium” site density contains between eleven and nineteen artefacts/m² and a “high” site density means that at least twenty artefacts were found in one m². Also the offsite density is taken into account: it is measured in a straight line pick up of fifty meters long. At most five artefacts means the offsite density is low, between six and fourteen artefacts stands for a medium offsite density and a high offsite density requires at least fiteen artefacts. These categories were applied on fields with good visibility, which means on the majority of the total surveyed area. Precise localisation and site mapping is achieved for all sites, with the help of GPS technology, cadastral maps (1/4 000) and IGM topographic maps (1/105 000). Additional drawings of other surface structures and some sections were also made. All information is stored in the all–encompassing PVS–database, which enables the information to be linked with digital maps in ArcView 3.2.

 

Geophysical prospections

Geophysical prospections.

Result of magnetic survey.

 

From 2004 onwards an important part of the fieldwork in the Potenza valley consists of geophysical surveys. The geophysical prospection was initiated with the aim of locating and mapping the remains of sub-surface archaeological features in the colony of Potentia, the Roman municipia of Septempeda and Trea, and on the rural site at Colle Burchio near Porto Recanati. This work has been done by the PVS team from Ghent University in close collaboration with teams from the Archaeological Prospection Services of Southampton University (APSS), The British School at Rome, the Ljubljana University Department of Archaeology and the company Eastern Atlas. These geophysical surveys aimed especially to detect many archaeological structures and buildings and elucidate details of the layout of the three mentioned Roman cities. Although a number of different geophysical survey techniques could have been applied on these abandoned city sites, magnetometer survey was chosen as a relatively time-saving and efficient survey technique, especially suitable for detecting kilns, hearths, ovens, ditches, and walls particularly where ceramic materials have been used in construction. Also electiric resistivity was widely used as it is most suitable for detecting walls, pavements, roads, ditches and voids. In targeted area of these sites also ground penetrating radar was used.

Geo-radar survey.

Electric resistivity survey.