THE JUDICIOUS SELECTION AND PRESERVATION OF TUFF AND TRAVERTINE BUILDING STONE IN ANCIENT ROME*

The Republican and early Imperial monuments of Rome are, for the most part, built of tuffs quarried from at least seven pyroclastic deposits erupted from nearby Monti Sabatini and Alban Hills volcanoes. Remarks by Vitruvius (2.7.1–5), field observations of the monuments, and petrographic and rock testing studies of samples from Roman quarries demonstrate that Roman builders developed a good knowledge of the diverse material properties of the tuffs over centuries of use and exposure. Measurements of compressive strength, specific gravity, water absorption and adsorption of water vapour confirm that the petrographic characteristics of each tuff lithology strongly influence its strength and durability. Early construction utilized weakly durable, soft or vitric tuffs such as Tufo del Palatino or Tufo Giallo della Via Tiberina that are susceptible to decay, as at Temple C (290 bc ) of the Largo Argentina Sacred Area. Late Republican structures, such as the Temple of Portunus (80–90 bc ), employed somewhat durable, vitric–lithic Tufo Lionato reinforced with travertine, a durable limestone quarried near Tivoli. Roman builders selected the material properties of the tuffs to advantage for specific structural elements within large public monuments of the first century bc and the first century ad , as at the tabernae of the Forum of Caesar (46 bc ), where an upper storey of lightweight Tufo Lionato is supported by robust, lithic–crystal Lapis Gabinus pillars and flat arches reinforced with travertine. The tuffs are not very durable building stones; Romans preserved them with protective stucco, and travertine and marble cladding. Their high water intake, coupled with direct exposure to rain, daily fluctuations in relative humidity and urban weathering at present makes them especially vulnerable to decay.     

A GEOARCHAEOLOGICAL STUDY OF THE ANCIENT QUARRIES OF SIDI GHEDAMSY ISLAND (MONASTIR,TUNISIA)

Amongst a large number of ancient quarries scattered along the North African coast, those at Sidi Ghedamsy (Monastir, Tunisia) have supplied building stones of Pliocene age. Two lithofacies have been distinguished in the quarry faces: (i) fine sandy limestone, which has been used in the construction of Roman and Arabic monuments; and (ii) porous and coarse limy sandstone, which is of bad quality for construction. Laboratory analysis results confirm that the exploitation of stone in antiquity was well focused on the levels containing the first type. This is confirmed by geotechnical tests, which show that the fine sandy limestone is harder and less porous than the coarse limy sandstone. Extraction of these stones began in the Roman period. The Romans exploited the quarries using steel tools that permitted the extraction of blocks from several levels. In the eighth century, Arabic quarry workers continued the stone extraction using the same technique, but they produced blocks of small and medium size. Statistical measurements have been done on the quarry faces and on the walls of the Ribat in order to understand the degree of conformity between the dimensions of the extracted blocks and those used for building, and ultimately to attempt to date the quarries and the construction of the Ribat.     

THE WRITING'S IN THE WALL: A REVIEW OF NEW PRELIMINARY APPLICATIONS OF ELECTRICAL RESISTIVITY TOMOGRAPHY WITHIN ARCHAEOLOGY

Natural processes are known to cause significant damage to archaeological monuments. In fact, the key to understanding the decay of building materials is the internal movement of water through the mineral matrix, which influences the distribution of chemical, physical and biological deterioration processes. Electrical resistivity tomography (ERT) was traditionally used as a surveying tool within archaeology, but a new high‐resolution technique that accurately traces the movement of moisture in building materials could provide a vital tool for understanding the decay of many archaeological monuments. This paper considers current progress, the shift of ERT from soil to rock research and the impact that this development could have on future conservation, using Hertford College (Oxford) and Neolithic rock art (Golden Gate Reserve, South Africa) as case studies.     

Preserving a Monument: The Example of the Parthenon

Abstract

The preservation of architectural relics of the past developed as a science mainly in the last century. The more a ruin is preserved, the more information it may provide about the past. Structural interventions on relics aim to improve their state of preservation for the future, as well as to render their shape more complete, for the overall purpose of safeguarding their historical information. Over the course of past decades interventions have undergone many changes with respect to methodology, materials, and scope. Intervention in the name of preservation can be interpreted in various ways and questions concerning the goals and nature of modern interventions have become particularly relevant. The current Parthenon Restoration Project, which differs in basic aspects from its predecessors, follows international guidelines for interventions, but remains distinctive for its extent as well as its methods of execution. This paper discusses the theoretical approach underlying the intervention and practical aspects of its methodology.     

THE DISCOVERY OF AN ANGLO‐SAXON GRUBENHAUS AT NEW BEWICK,NORTHERN UK USING ELECTRICAL SURVEYING AND PREDICTIVE DECONVOLUTION

Twin‐probe and 33‐fold multiplexed Wenner electrical resistivity surveys were carried out at New Bewick, northern UK to examine the extent of crop marks and potential Grubenhäuser (sunken‐featured buildings, sunken‐floored buildings or SFBs). The twin‐probe method was faster, but provided data with a lower spatial resolution. However, the Wenner array data was affected by characteristic ‘M’‐ or ‘W’‐shaped responses over filled excavations such as those expected to represent a Grubenhaus. The raw Wenner array data have been analysed using one‐dimensional and two‐dimensional predictive deconvolution in order to remove these artefacts. The deconvolution was carried out using an inverse matrix element method. The filtered results indicate the presence of anomalies consistent with the presence of at least six Grubenhäuser and other anomalies concurrent with the linear crop‐marks. One particular anomaly measured about 5 m by 4 m and with a pit depth of 0.6 m below 0.3 m of topsoil. This anomaly was subsequently excavated and a Grubenhaus was discovered at the site. The excavated Grubenhaus measured 4.7 m by 3.9 m with a pit depth of 0.5 m below the base of the topsoil, confirming the electrical survey results.     

AN 8500‐YEAR‐OLD BLADDER STONE FROM UZZO CAVE (TRAPANI): FOURIER TRANSFORM–INFRARED SPECTROSCOPY ANALYSIS*

A calcium carbonate (calcite) bladder calculus was found in the pelvis of an adult female buried in a Mesolithic cave‐tomb on the coast of Sicily; it was dated by ¹⁴ C to around 6500 bc . Its chemical composition, which was not known before, was determined by means of Fourier transform–infared microspectroscopy (FT–IR–M) using the high‐pressure diamond cell, a device that makes it possible to analyse a small amount of the sample (1–2 µg). In this way, the analysis of all the laminations of the calculus was performed without destroying the sample. Although calcite was the main component, carbonate apatite was also detected in the nucleus and in a more external layer.     

MEDIEVAL BRICK‐BUILDING IN THE CENTRAL ALPS*

Since Roman times, the Alpine area has been the scene of all movements in brick construction—certainly only in a few places, but always at a high technical and aesthetic level. This is all the more surprising as in the mountain areas sufficient stone material is available in a suitable quality for building. Obviously, brick materials displayed overwhelming advantages. Via the mediation of the Church and the secular managerial class, the latent capacity of brick technology was able to rapidly gain a foothold as ideas began to flow internationally. Every era has discovered particular advantages in the use of brick and has expressed them in its architecture.     

Archaeological Site Management and Local Involvement: A Case Study from Abu Rawash,Egypt

Abstract

Local involvement is an essential element of successful archaeological site management. Recognition of the role of the local community could make a great contribution in improving the present critical situation of many archaeological sites worldwide. In Egypt, where internationally renowned archaeological sites attract both academic and tourism interests, archaeological sites and monuments are suffering from different issues. Amongst the various causes is the failure to recognize the relationship between the sites and the present society — both the local community and other stakeholders — and this has negatively influenced the sites. Not only have the local communities been given limited access to knowledge, and limited opportunities to become involved in the archaeology, but also their attempts to pursue a better standard of living have been restricted for the sake of protecting the national heritage. In this article I use a case study from Abu Rawash to explore strategies that could encourage local involvement in site management, through capacity building and communication with the government and other stakeholders. Although local involvement may not provide a drastic improvement of an individual site's condition, the principle of local involvement should contribute to a general improvement in Egypt, where conservation efforts largely focus on physical materials and little attention is given to the society surrounding the archaeological remains.     

MORTAR STUDIES TOWARDS THE REPLICATION OF ROMAN CONCRETE

The use of strong and durable materials is one essential ingredient leading to the survival of many monumental Roman concrete structures. Replicated concrete mortars with different lime to pozzolan ratios, encompassing the range likely to have been used by the Romans, have been studied here to determine their relative compressive strengths as a function of time. This has been supplemented by the use of the scanning electron microscope to delve into the structure and composition of the binders formed within the strongest and weakest mortars, leading to a deeper understanding of the reasons for the differences in compressive strength.     

STONES FROM MEDIEVAL GLASSMAKING: A SUITABLE WASTE PRODUCT FOR RECONSTRUCTING AN EARLY STAGE OF THE MELTING PROCESS IN THE MT LECCO GLASS FACTORY*

The Mt Lecco glass factory was one of the most important production centres in Liguria (Italy) during the 14th and 15th centuries. Archaeological evidence indicates that the whole production cycle took place here. During the glassworking process, production defects such as ‘stones’ were identified and discarded. Stones are partially melted, glass‐coated relics of raw materials or fragments of crucible. The study of the microtexture of stones together with microprobe analyses of phases provides a key for understanding the glassmaking procedure carried out in the Mt Lecco glass factory. The melting rate can be inferred from the compositional variability of glass, which suggests fractional melting of the batch. Glass composition indicates that the Mt Lecco production was a mixed‐alkali one, probably made of quartz‐bearing material as vitrifying agents, plant ashes as fluxing agents and dolomitic limestones as stabilizing agents.