PAVLOPETRI - 2010

Informations Générales

Numéro de la notice

1893

Année de l'opération

2010

Chronologie

Néolithique - Néolithique Final

Âge du Bronze - Bronze Ancien - Bronze Moyen - Bronze Récent

Âge du Fer - Géométrique

Antiquité - Classique - Romain

Période byzantine

Mots-clés

Maison - Sépulture - Outillage/armement - Terre cuite architecturale - Pierre - Habitat

Nature de l'opération

Prospection

Institution(s)

British School at Athens (BSA) (École britannique à Athènes)

Εφορεία Εναλίων Αρχαιοτήτων (Éphorie des antiquités sous-marines)

Ελληνικό Κέντρο Θαλασσίων Ερευνών - ΕΛΚΕΘΕ (Centre hellénique de recherche marine)

Localisation

Toponyme
Pounda Akra

Notices et opérations liées

200920102011

Description

Pavlopetri. J. Henderson (BSA/Nottingham), E. Spondylis (EEA) and D. Sakellariou (Hellenic Centre for Marine Research) report on the second field season conducted in 2010. The project aims to outline the development of the submerged prehistoric town at Pavlopetri and through a systematic study of the geomorphology of the area, to explain how the prehistoric town and the Strait of Elaphonisos became submerged.

Recording of the surviving architectural remains was completed using modern digital techniques. Alongside survey of the structural remains using a shore based Total Station (Figs 1-2), more extensive use was made of the Sector Scan Sonar trialed in 2009, and a new stereo-photogrammetric system of underwater mapping was tested. The Kongsberg-Mesotech MS 1000 Sector Scan Sonar system consists of a sonar operating computer housed on a boat which directly connects through a high tensile weight cable to a sonar head unit hung from a movable stainless steel tripod in the water (Fig. 3). Typical scan radii used for the submerged structures at Pavlopetri ranged from 100m scans of building complexes (covering a total sea floor area of 31,000m²) (Fig. 4) down to very high resolution 5m scans of areas of importance such as cist graves. Radii of 15-30m proved most effective for producing measured scans of buildings in which the individual stones used in the construction of the walls were visible. In order to fully image individual buildings at Pavlopetri at least one scan from within a building was backed up by at least four separate scan locations around the perimeter to eliminate areas of acoustic ‘shadow’ (Fig. 5). 214 drops were carried out in 2010 covering the site in its entirety. All of the upstanding structural elements of the site - buildings, streets, courtyards, walls and graves - were recorded in three dimensions alongside the topography of the seabed. The data produced by the sector scan sonar can be manipulated in 3D environments to produce isometric images of the building complexes.

A stereo-vision mapping system designed by the Australian Centre for Field Robotics was used for the first time to survey and record an archaeological site. This consists of digital stereo cameras with LED flashes, a GPS receiver, a multibeam sonar, hard disk and power module attached to a rig which can be manually propelled by a diver over areas of interest (Fig. 6). The stereo-cameras obtain measured two dimensional photo-mosaic maps of areas of the seabed quickly and efficiently. These high resolution mosaics can then be processed using Simultaneous Localisation and Mapping software to produce accurate three dimensional models. In addition the multibeam sonar on the diver rig can obtain three dimensional data on seabed surfaces that can be combined with the stereo-photogrammetric data.

In 2010, priority was given to recording areas containing structures of the highest archaeological importance. A total of 47 dives were carried out, gathering more than 135,000 pairs of stereo images. Post-processing of such a quantity of data is expected to take at least one year to complete. However preliminary results prove that the technique is sound. For example, in one survey box (15 x 30m) containing Building IX and parts of Street 1, 6,315 stereo image pairs were acquired. Walls can be clearly seen in both the photo-mapped view in Fig. 7, and the depth-coloured view in Fig. 8. Fig. 9 is a detailed view of Building IX. Fig. 10 is an overhead view of another mesh created of Chamber Tomb 1 located on the bedrock ridge to the north-east of the city. The tomb was cut from the surrounding bedrock, producing a structure with large depth variations. Overall, preliminary results suggest that the 3D reconstructions provide a representation very suitable for archaeological interpretation, both as a visually coherent composite view of the site and as a three- dimensional model.

The visible architectural remains at Pavlopetri begin some 20m from the shore at Pounda Beach and run over 300m south out to Pavlopetri island (Fig. 1). They are bounded to the east by a bedrock ridge running north to south, and to the west by extensive sand deposits and deeper water (no remains have been identified in depths exceeding 3m). Beyond Pavlopetri island and the eastern ridge the sea is deeper and no artificial constructions can be traced. Nothing to indicate the existence of artificial harbour constructions or jetties could be identified in 2009 or 2010. The town appears as a series of large spreads of stones indicating building complexes, amongst which a network of stone walls can be traced (Fig. 11). Walls are made of uncut aeolianite, sandstone and limestone blocks and were built without mortar. They can survive up to 3 courses high but the vast majority preserve only one course or are completely flush with the sea bed. The submerged remains recorded in 1968 can be clearly identified and survive in approximately the same condition. The existence of the eastern rocky ridge has protected the remains from the full force of wave action over the years; where there are gaps in the ridge, walls have been eroded either completely away or flush with the seabed.

In addition to the recording of the 30,000m² of buildings first identified in 1968, over 9,000m² of new structures were discovered emerging from the sand to the north of the original remains in 2009, whilst in 2010 a further 5,000m² of buildings were found to the south of the main concentration of buildings (Fig. 1). This last area consists of the remains of at least 7 buildings clustered along a street running south west to north east. Four new cist graves were recorded in 2010 bringing the site total to 43. The discovery of major new areas of the site in 2009 and 2010 suggest that the town is larger and more important than previously thought. The visible remains now cover almost 4 hectares. Given that there are probably many more buildings hidden under the sand, and that scattered fragments of walling suggest that the town originally extended as a fully built-up area as far as Pavlopetri island, the settlement is likely to have covered at least 8 hectares. The lack of rubble from the site as a whole suggests that the surviving walls represent the ground floor of buildings with stone foundations to around 1m in height and superstructures of mud brick and/or timber frames covered in plaster. Only the very base of the wall was stone, probably to prevent the foundations from being eroded.

It is likely that these newly exposed remains had been covered by sand deposits in previous years, a suggestion borne out by the cleaner appearance of the stonework in the new areas compared to the older areas which feature well established marine algal species and encrusting marine organisms. Changes in sand cover could relate to changes in the position and shape of the shoreline over time causing variability in wave action. Equally the map of the bathymetry and topography of the town and the eastern bedrock ridge shows low gaps in the ridge where wave action would pass through and be diffracted and refracted round Pavlopetri Island and the other high points. This would result in a focusing of wave energy at discontinuous points over the town and the adjacent beach, with a pattern of high and low energy determined by the recent wave direction. While this shifting pattern is not yet understood, the discoveries made in 2009 suggest that revisiting the site in future years and at different seasons may reveal further parts of the Bronze Age town which are at present under thick beds of sand.

Since the majority of architectural remains were more exposed than in 2009, large amounts of pottery were revealed including almost intact pithoi (Fig. 12). Lifting of archaeological material was undertaken across these areas to recover endangered material and obtain further dating evidence. Seven collections were carried out and a total of 395 artefacts (pottery and stone tools) recovered. The pottery lifted confirmed and refined the dates obtained in 2009. The site was first occupied in the Final Neolithic, as suggested by jars and fruit stands. The Early Bronze Age is largely represented by jars and pithoi, sauceboats, beaked jugs, pyxis (lids), tripod vessels, plates and portable hearths. A relative large number of grinders of various stones have been recovered. along with a phyllite disc with exact parallels from Ag. Stephanos. The Middle Bronze Age is represented by fewer open jars and closed vessels, basins and cups. The majority of lifted material dates to the Late Bronze Age (MB III/LB I to LH IIIB/C) and consists of nearly all known pottery types (e.g. kylikes, pithoi, jugs and jars, cups, goblets and deep bowls, incense burners, tripod vessels and cooking pots, loomweights). The Neopalatial material (pithoi, jugs, alabastron, scoops etc.), both imported and locally produced, shows close affinities with material from Kythera and Crete. Only one LG II sherd with painted decoration was lifted. A few drinking vessels (cups, kylikes) date to the Classical period. An intact Roman lamp was lifted along with several Roman and Late Roman amphora, jar and cooking vessel sherds, and Byzantine transport amphorae. Terracotta architectural elements were discovered, namely roof and drainage tiles, mudbrick and clay settings for rafters.

Auteur de la notice

Catherine MORGAN

Références bibliographiques

Unpublished field report, British School at Athens