THE ROMANESQUE FRIEZE AT LINCOLN CATHEDRAL (ENGLAND)—PRIMARY OR SECONDARY INSERTION? MAGNETIC CONSIDERATIONS*

The current debate about the age of the Romanesque frieze of Lincoln Cathedral weighs archaeological evidence against art history. On the one hand, the panels appear to be an integral part of the original Norman structure built by the first bishop (AD 1072–92). However, on grounds of style and artistic comparisons, art historians argue for a later installation during the restoration of AD 1141–6. In order to determine when the panels were stabilized in the cathedral, we used a new method that measures their degree of remagnetization by the earth's magnetic field since they were quarried. The longer that masonry remains stabilized in a given orientation, the greater its viscous remagnetization. Viscous remanent magnetization dating has previously been successful with this particular type of limestone masonry. Our results lend support to the view that the panels were installed in the early 1140s.     

RESEARCH REPORT: MAGNETIC INVESTIGATIONS AND THE AGE OF A MEDIEVAL KILN AT KUNGAHÄLLA (SOUTH‐WEST SWEDEN)*

The results from a magnetic survey and archaeomagnetic investigation of a medieval brick kiln at Kungahälla in Bohuslän (south‐west Sweden) are reported. Detailed magnetic total field and magnetic gradient measurements over known traces of the kiln showed marked local magnetic anomalies of up to 200 nT, revealing the rectangular shape of the kiln remains. Palaeomagnetic investigations of the remanent magnetization of 12 bricks from the kiln floor gave precise definitions of both the direction of the archaeomagnetic field [(D_m, I_m) = (66.7°, 8.8°), k = 655, α₉₅= 1.7°] and the palaeointensity [B_m= 69.0 ± 3.6 µT]. An archaeomagnetic date is obtained by comparing the direction of the archaeomagnetic field found in the kiln with a geocentral dipole‐transformation of the British master‐curve for secular variation. Of two possible archaeomagnetic dates (ad 1280 ± 50 or ad 1480 ± 50), the ad 1280 ± 50 age is in good accordance with the C‐14 ages and archaeological dates as well as with direct historical evidence, whereas a c. 100 years younger TL date appears to be too young.     

LASER ARGON DATING AND GEOLOGICAL PROVENANCING OF A STONE AXE FROM THE STONEHENGE ENVIRONS*

The recently-developed laser microprobe ⁴⁰argon-³⁹ argon technique has been used to give a geological date for a rhyolitic tuff stone axe fragment from the Stonehenge environs. The method requires only milligramme-sized samples and gives dates of sufficient accuracy to aid in provenancing artefacts to sources, as well as information on the heating history of samples. The axe sample is of Lower Carboniferous date (341 ± 5 Ma) and this limits possible sources to outcrops within the Scottish Midland Valley and small altered exposures in Dartmoor. X-ray fluorescence analysis of the axe suggests the Scottish Midland Valley as the more likely source. The laser argon analysis also shows that the implement had not been heated in antiquity. Laser argon-argon dating can, therefore, be a useful tool in artefact study.     

A MULTIDISCIPLINARY APPROACH TO THE CHARACTERIZATION OF ROMAN GRAVESTONES FROM AQUILEIA (UDINE,ITALY)*

The results of an archaeometric study on gravestone production in Aquileia (northeastern Italy) during Roman Republican times are reported here. The artefacts are made of limestone, quarried from the sedimentary sequence of the Trieste Karst (Carnican Alps, northeastern Italy), as testified by historical sources which refer to the ‘Roman Quarry’ at Aurisina. The rock types used for the gravestones are petrographically, geochemically and geochronologically homogeneous, and display similar faunal assemblages. In addition, their age is restricted to the Santonian – Lower Campanian. Comparisons between archaeological finds and rock specimens from various active and inactive quarries in this area suggest that quarrying during Roman Republican times was limited to a specific stratigraphic horizon of the sedimentary sequence, corresponding to the higher part of the ‘Roman Quarry’.     

LOCALIZING HISTORICAL CLUES USING IRT AND PETROGRAPHIC ANALYSES AT VILLA MIRABELLO,MONZA (ITALY)*

The rebuilding of Villa Mirabello started in 1666. Built on designs of Gerolamo Quadrio, the project refurbished and enlarged a smaller 16th century country house (‘casa da nobile e da massaro’). Archival documents report on the remodelling, which consisted of selective demolition of portions of the structure, re‐using most of the masonry as the core of the new building, and the reinforcement of retained masonry by insertion of ‘ceppo’ stone quoins to update new exteriors. The aim of Quadrio was to create an elegant and sumptuous mansion, suitable for noble owners such as Giuseppe Durini and his family. The plan and a small part of original finishing (‘marmorino’ plaster decoration) are recognizable nowadays. Nevertheless, there are many questions in interpretation when one compares the documents and the building. That is, Cardinal Angelo Durini made a major modification in the 18th century, and further minor changes were made in the 19th century. Although these latter modifications did not alter the plan, they changed the distribution of rooms and masked both decoration and finishing. After over 20 years of neglect, Villa Mirabello is now close to being restored. Architects in charge ordered a preliminary set of diagnostics to assess damage and study the historical evolution of the building. Integration of IR thermography (IRT) and endoscopy allowed restorers to detect the structure's texture underneath the plaster, and to detect openings filled with masonry. Moreover, archive documents confirmed these results and, above all, defined a date for the use of specific building techniques. This research constitutes a reference for buildings set in the same time and location that do not have significant archival documentation. Active IRT provided useful information for structural assessment (such as location of arches, chimney stacks, different thickness of wall, wooden elements, voids, beams etc.) and for crack pattern evaluation. This information directs design professionals working on this conservation project, and helps define the costs of intervention.     

A PROVENANCE STUDY OF POTTERY FROM ARCHAEOLOGICAL SITES NEAR CANOSA,PUGLIA (ITALY)*

Studies have been carried out to assess the provenance of selected pottery excavated at archaeological sites near Canosa, Puglia (Italy). Sixty-six sherds, ranging in date from the mid-seventh century BC to the beginning of the third century BC, were analysed by atomic absorption spectroscopy and 16 elements were determined. The analysis data were subjected to multivariate classification procedures. Tests showed that the majority of the examined sherds came from ancient local kilns; a probable Ionian origin was established for some other sherds, while the rest were of unknown origin.