News 2013

Archaeological Investigations in the Potenza Valley - Field Season 2013

In 2013, the team of the Potenza Valley Survey project (PVS) has carried out a series of activities within the whole valley: field investigations were focused around the abandoned Roman coastal town of Potentia,  on the urban sites of Ricina and Trea (photography, geophysical prospections, augerings, research into the ancient rural exploitation systems and the exploitation and use of stone building materials), drone photography of the important Iron Age hilltop site of Monte Pitino, GPR survey in Septempeda and a series of geomorphological test-augerings in the Pioraco area. Progress has also been made in the study of archaeological materials (e.g. Roman lamps, decorative stone) deposited at the municipality of Porto Recanati.

 

Fig. 1 Shooting of some of the July 2013 field activities in Porto Recanati for a European funded video documentary about the Project “Radio-Past”.

Archaeological aerial remote sensing and image processing in the Potenza valley

In June 2013 a short Unmanned Aerial System (UAS) campaign was organised in the framework of the Potenza Valley Survey (PVS). To this end, a Microdrone md4-1000 UAS was brought from Vienna to Porto Recanati. In total, sixteen flights were executed above the Roman towns of Potentia, Trea and the hilltop called Monte Pitino. The overall aim of all these flights was to generate aerial imagery that could afterwards be used for documentation purposes, three-dimensional (3D) modelling, Digital Surface Model (DSM) extraction and orthopoto production.

 

Day	Location	Flights	Cameras	Aim
13-06-2013	Potentia	3	Sony NEX-5N & NEX-5NFS	Documentation of the excavation area and testing of the complete UAS and camera setup.
14-06-2013	Monte Pitino	5	Sony NEX-5N	3D model of the hilltop and its buildings.
15-06-2013	Trea	6	Sony NEX-5N	DSM creation and documentation of the vegetation marks in the visible light.
16-06-2013	Trea	2	Sony NEX-5NFS	Documentation of the vegetation marks in the NIR.

Fig. 2 Overview of some UAS flight parameters.

 

Fig. 3  NIR overview image of the excavation area (Potentia). © Geert Verhoeven

 

Fig. 4 Trea. The newly created orthophoto displayed in Google Earth Pro together with the three md4-1000 flight tracks. Here, it can be seen that this newer Google image is less accurately georeferenced, as the data do not line up perfectly.

If this campaign learned something, it is that a fast and accurate post-processing workflow of images into accurately georeferenced 3D models and orthophotographs necessitates the indication of new GCPs just before the UAS flights. Second, these results also clearly show that the final result is highly dependent on the workflow, the parameters used and the skills of the person using the software. Although most people that use SfM and MVS in their processing chain just feed the software with some images and run everything in automatic mode, a deeper understanding of what is going on and what can go wrong is of the utmost importance to yield the best possible output.

Third, it can be noted that two md4-1000 batteries is too little if one wants to perform repeated flights. Finding a place to charge the batteries is not always straightforward, while the age of the batteries resulted in serious reduced flight times: new batteries yield flight times up to 45 minutes, while the current batteries only last for twenty minutes of safe flight.

Geoarchaeological augering in the suburbium of Potentia and on Montarice hill 

In July 2013 an augering survey was undertaken in the surroundings of the Roman colony of Potentia and the promontory Montarice hill (Marche, Italy). The survey was initiated with the objective of understanding the ecological and geomorphological history of the sites, with focus on the Iron Age and Roman period, and their relation with human activity.

Potentia extra muros

This survey aimed at achieving more detailed information about the necropolis area and to proof the predicted location of subsurface archaeological features based on the results of the magnetic survey conducted by Eastern Atlas, during the 2012 field season. Additional geophysical survey were carried out on this site during the 2013 campaign, including a Ground Penetrating Radar (GPR) survey (carried out by Lieven Verdonck, Ghent University) and a resistivity survey (by Eastern Atlas). In the next phase, these results will be correlated with the results of the augering and magnetic survey. Important results were obtained regarding the Roman wetland landscape directly west of the colony and the presence and position of monumental graves on both sides of the decumanus maximus leaving the town from its West-gate.

 

Fig.  5 Overview of the augerings carried out in Potentia extra muros with a more detailed view of the locations of boreholes 16, 19 and 20.

Montarice hill

The second surveyed site is situated on the promontory Montarice, immediately north of the present course of the Potenza River. The site has a long settlement history starting in the Bronze Age.

In 2002, artefact surveys were carried out and during the 2012 campaign, a resistivity profile was laid out by Eastern Atlas at the northern edge of the site. To verify and enhance the results of the resistivity survey, ten augerings were undertaken along the 90 m long resistivity profile during the 2013 field season. In addition, two augerings (1 and 2) were executed in the NE-corner of the plateau to investigate the presence and depth of an archaeological horizon. The results learned that this important protohistoric site needs urgent protective measures as the thickness of archaeological layers has much eroded in modern times.

               

Fig. 6 Location of the resistivity profile and of boreholes 1 and 2.

Geomagnetic and resistivity surveys in the Lower Potenza valley

In July and additionally in October 2013, geophysical surveys were undertaken by the geophysical survey company Eastern Atlas, in the lower part of the Potenza valley as part of the PVS Project. The magnetic survey was initiated with the objective of locating and mapping remains of subsurface archaeological features in the Roman town of Ricina, about 30 km southwest from the coast, the Roman villa site of San Girio at the southern edge of the Potenza plain and on Montarice hill, situated north of the Roman colony of Potentia (Fig.7). Aerial photography, conducted by Prof. Frank Vermeulen has revealed various building (Ricina, San Girio) and defense structures (Montarice) in these areas. To gain additional information about subsurface structures in depths not accessible by magnetic gradiometry a resistivity imaging system was used near the western gate in the extra muros area of Potentia. The resistivity survey was accompanied by augering to combine the layer stratigraphy from resistivity imaging with detailed soil samples.

 

Fig. 7 Overview of the locations in the Potenza Valley, surveyed magnetically in the 2013 campaign.

 

Fig. 8  Magnetic survey of the northern part of Ricina (Dynamic range +- 5nT). Revealed were parts of a possible temple complex and houses of the Roman town.

 

Fig. 9 Magnetic survey of the Roman villa site at San Girio (Dynamic range +- 5nT). Large parts of the villa walls and floors were revealed, including a series of Roman terracing walls.

GPR prospection at Iron Age and Roman sites in the Potenza valley

GPR is a survey method appropriate for the detection of structures in stone. Moreover, it is capable of yielding high resolution images of the subsurface, in three dimensions (including depth). A drawback is the attenuation in certain soils, particularly in humid clay soils. The 2013 GPR survey in the Potenza Valley took place at six sites. At three of those  (Potentia, San Girio and Septempeda), only few of the structures known from field walking, aerial photography or other geophysical prospections, were detected. This can be attributed to the combination of two factors. (1) The conductive soils, with a clay content of sometimes more than 50 %, attenuate the radar waves to a large extent, even in dry circumstances as in July 2013. (2) Given the unfavourable soil conditions, the structures are buried beyond the depth range of the instrument (> 1 m for the funeral monuments at Potentia; > 2 m for the walls at Septempeda; for San Girio the depth is not known exactly). At two other sites, traces were revealed, although only in a small part of the prospection area. At Montarice, the features only show in the northern part, whereas other defences are known from the fluxgate gradiometer survey and the aerial photographs. At Ricina, the presence of rubble in the shallow layers around the temple and a large building near the overgrown cistern, resulted in relatively clear images of the subsoil to a depth of ~1.5 m. Nevertheless, this represents only a very small part of the survey area; elsewhere the known walls remained invisible for the GPR. At Trea, the circumstances of the survey (presence of straw, and of straw bales later on) prevented an efficient prospection of a sufficiently large area. Few traces are visible in the vertical profiles. 

 

Fig. 10  Location of the areas surveyed in 2013 (green): Potentia (no. 1), Montarice (no. 2). Sites indicated in orange were surveyed in 2012. Coordinate system: Gauss-Boaga - Fuso Est.

 

Fig. 11 GPR slice from Potentia, at an estimated depth of 55- 60 cm, showing traces of the Roman road (no. 1), and of a small ditch, still visible at the surface (no. 2). Coordinate system: Gauss-Boaga - Fuso Est.

Geoarchaeological augering at the Roman town site of Trea

In July 2013 an augering survey was undertaken at the archaeological site of Trea near modern Treia, under the coordination of Prof. M. De Dapper. The survey was initiated with the objective of obtaining an insight into the on-site geomorphology of the Roman town. The landscape modification and possible leveling of the plateau on which the Roman town was constructed were hereby of particular interest. In addition, the augering survey aimed at providing a better context for the interpretation of the results of the geophysical surveys carried out in previous research campaigns and at obtaining information on the conservation of the archaeological remains. In total, 54 augerings were carried out.

 

Fig. 12 Location of the augerings at Trea based on the orthophoto obtained from oblique aerial photography.

 

Fig. 13 Impressions of the fieldwork.

The main observation of the survey concerns the conservation of archaeological structures and the thickness of the archaeological strata. In general, the augerings that were located on positions that correspond to anomalies detected as crop marks on oblique aerial photographs have illustrated the presence of shallow archaeological remains (walls, floorings, etc.).

Further processing of the samples taken during these augerings, in association with on-going detailed interpretative mapping of all archaeological structures detected during several years of intensive survey at Trea, will allow the PVS team to achieve, in the near future, a final proposition for the 2D plan of the Roman urban site. The results and interpretations should also include specific recommendations for the protection and future management of the site.

The study of the pottery from prehistoric, Roman and medieval Potenza valley sites

The focus in the 2013 season was on the material of the protohistorical village site of Montarice and the Roman town of Ricina. The choice for these two sites was decided in order to confront the finds with the results of the recent geomorphological, geomagnetic and ground-penetrating radar surveys (cf. supra) so that they can deliver chronological clues and, where possible, contribute to determine functional zoning.

The second focus was on the specialized study of material categories, i.e. lamps, whereas the amphora dossier was enriched with two new types of Iberian amphorae (Dressel 7-8 in Trea and Almagro 50 in Ricina).

Montarice

One of the questions indeed was if the first generations of Roman colonists (first half of the 2nd century BC) also settled on the hill. This turned out to be positive since all the typical material that characterizes these early settlements are present : Greco-Italic amphorae and plain ware in ‘Colle Burchio’ fabric, other plain wares, coarse ware, black gloss, cooking ware from Campania (Vesuvius region) and Rhodian amphorae.

 

Fig. 14 Montarice : spike of a Greco-Italic amphora, the Colle Burchio workshop production, c. 180-150 BC.

Medieval pottery on the contrary seems to be present in appreciable quantities but a lack of experience with these categories of pottery seriously hampers our study at present. In the light of her research on the early Medieval times in the Potenza valley and the Marche Dr Francesca Carboni aid special attention to the pottery of this period. Some chronological and typological groups were tentatively separated.

 

Fig. 15 Montarice : early Medieval pottery, 7th-9th centuries AD?

Lamps

Most of the lamps found during our full valley surveys and two excavations (W-gate of Potentia and an amphora production site in Potenza Picena) were discovered in urban sites, but the fact that they were rarely found on rural sites has probably something to do with their degree of fragmentation and therefore their visibility. 178 lamps were studied and described in detail : 144 come from Potentia, 14 from Ricina, 4 from Trea and 16 from different rural or production sites. It was not possible to identify the typology of 31 lamp fragments.

 

Fig. 16 Lamp type Deneauve Vg found in Trea, c. 50-110 AD (C12- Treia-2010-13/09/10).

The study of the stone architectural decoration from the Roman sites of Ricina and Trea

A study of the stone architectural decoration from the Roman town of Ricina (Villa Potenza) was carried out in the July 2013 campaign. The material studied has been collected by the PVS team of Ghent University during a systematic artefact survey in autumn 2005. The main aim was a qualitative and quantitative assessment of the different rock types used for the embellishment of the town. The study is part of a larger scale project that studies the distribution and trade of marble in the Central Adriatic region of Italy in Roman times. More specifically, the project aims to study the marble use and the marble provenance from different sites in the study area in order to gain new insights in the mode of distribution and the social-economic mechanisms that were involved in the large-scale import and export of marbles in the Roman period. In the project, the white and coloured marbles used at several Roman sites in the study area are studied systematically. Unlike most marble provenance studies that focus on the petrographic and archaeometric investigation of single marble artefacts (generally sculpture),the aim of this project is to approach the problem from a quantitative point of view as well, allowing a better understanding of the proportions and importance of certain marbles at certain sites.

 

Fig. 17  Location of the systematic artefact survey carried out on the site of Ricina by the PVS-team in 2005 (marked by a blue box). Background is an orthophoto of the site enhanced for display of vegetation marks (Verhoeven et al. 2012: 2065): (1) forum complex with temple building, (2) domus building, (3) cistern, (4) remains of the Roman theatre, (5) amphitheatre.

 

Fig. 18  Overview of the polychrome marbles found during the 2005 Ricina survey: (A) cipollino verde; (B) verde antico; (C) breccia corallina; (D) fior di pesco; (E) portasanta.

The distribution of the marble fragments clearly illustrates a larger concentration in the western area of the survey. Remarkably, only a low volume of marble fragments have been retrieved in the zone of the forum, a complex that originally must have been lavishly decorated. The absence of the marble material in the forum complex can be explained as the result of Medieval (or later) spoliation. The magnetic survey carried in 2013 on this part of the Roman town has identified twenty-one strong dipolar anomalies of with very high amplitudes that are probably limekilns, similar to detected kilns in other surveys of the Potenza Valley.

Study of the Roman town sites in the Potenza valley from Late Antiquity to Medieval times

In the course of 2013, an in-depth study started of the transformations that have affected the urban centres from Late Antiquity onwards, focusing in particular on the manner and timing of the abandonment of the four cities of the Roman era : Septempeda, Trea, Ricina, Potentia.

During the campaigns in June and July the analysis started of materials related to the youngest layers in the stratigraphy of the excavation of the West-gate of Potentia and of early medieval pottery fragments from the survey of Helvia Recina, stored in the archaeological depotof the Municipality of Porto Recanati. At the same time archive research and an analysis of the remote sensing data of the site of Ricina delivered interseting new ideas concerning the pace and character of urban abandonment.

 

Fig. 19 Location of geomagnetic anomalies, to be interpreted as lime kilns connected with the spoliation of archaeological structures in the northern part of Ricina: interpretabili come calcare (in red on the remote sensing imagery, in orange on the interpretative plan.

Ancient rural exploitation in the Potenza valley: viticulture and oleoculture      

The discovery of a late antique press in Treia (SS. Crocifisso)

During the July 2013 campaign a quadrangular stone press bed was uncovered just outside the north-western corner of the city walls of the Roman town of Trea (Fig. 20). Its location close to the town centre of ancient Trea is peculiar and its discovery marks only the second example in the region of a production installation placed within, or adjacent to, an urban context, next to the one found at Potentia in the lower Potenza valley (Mercando 1979).

The recycling of large and robust building materials into monolithic press elements – such as press beds, base blocks and counterweights – especially formed a recurrent practice in late antiquity and numerous examples have been attested at several sites across the Roman Mediterranean. When attested in a late antique urban context, it has been argued that its presence probably reflects a partial re-ruralisation of the town area in periods of urban decline and abandonment. The location of the press bed at Trea near the city walls and the monumental centre of the Roman town could hint at a similar scenario. If correct, this would put the dating of the press in the 3th - 4^th c. AD, or even later.

 

 

 

Fig. 20 Late antique press found in Trea (SS. Crocifisso).

Ethno-archaeological research concerning traditional viticultural and oleocultural practices

Since January 2011, within the framework of the PVS-project, the character and the evolution of the rural exploitation of the Potenza valley and the wider Marche region in Roman times (200 BC – AD 100) are being studied by means of a doctoral research project at the universities of Pisa and Ghent (D. Van Limbergen). The study essentially focuses on the production, the consumption and the export of wine and olive oil throughout this period. In particular, the aim is to better understand the shifting balance between intra-regional consumption and extra-regional export of these products through time. Therefore, the project makes use of archaeological land evaluation in order to confront potential agricultural production with local consumption needs. The purpose of the land evaluation is to assess the suitability of the different landscape sets in the Potenza valley for viticulture and oleoculture. Within this context, the development of comparative perspectives on wine and oil production in the Marche region by examining soil choice, planting strategies and crop yields by farmers in contemporary Marche can be of much value for supplementing ancient, medieval and pre-industrial literary sources on the subject, that are often fragmentary in nature, potentially biased, and whose accuracy can be debatable. Therefore, during the previous PVS campaign in September 2012, fieldwork was carried out by means of terrain checks and interviews with local farmers (see PVS 2012 report). During the July 2013 campaign, additional data were collected and further field checks and interviews were conducted in the middle sections of the Potenza valley. The first part of this contribution preliminary discusses the seven sites that were examined. These are all situated in the vicinity of the Roman towns of Trea (Treia) (5) and Septempeda (San Severino Marche) (2).

 

Fig. 21 Treia Monastery; site of the Roman town and nearby olive cultivation.

Exploratory palaeo-environmental study in the Pioraco study area

Members of the Geography research group (Department of Earth and Environmental sciences) of the University of Leuven, joined the campaign for an exploratory palaeo-environmental study in the upper part of the Potenza river catchment. The main research interests are the identification of major soil erosion and sediment deposition phases, and linking these phases to land use or climatic events. Through the application of quantitative techniques, like sediment budgeting, it is possible to get insight in the sediment cascade, and the importance of the human impact on the landscape. In addition they have a broad experience in palaeo-vegetation reconstruction in a Mediterranean environment through pollen analysis.

During July 2013, this team did an exploratory study to determine the research possibilities for:

-          A palaeo-vegetation reconstruction based on a palynological study

-          A quantitative geomorphologic study of the sedimentation rates during the different occupation phases from the Bronze Age to the Medieval Time Period

 

Fig. 22 Location of Pioraco and Montelago (background upper part: National Geographic Basemap, ArcGIS; background lower part: Open Street Map, ArcGIS).

A field recognition visit was combined with a hand coring campaign to get an idea about the local geomorphology, the extent of the travertine dam and lake deposits, the thickness of the lake deposits and its potential for preserving pollen. The coring campaign focused on the formed lake deposits west and south of the village of Pioraco.

 

Fig. 23 Location of the different corings (background: Imagery Basemap, ArcGIS).