MAGNETIC SUSCEPTIBILITY VARIATIONS AT MONS CLAUDIANUS AND IN ROMAN COLUMNS: A METHOD OF PROVENANCING TO WITHIN A SINGLE QUARRY

Mons Claudianus in the Eastern Desert of Egypt was an important source of granodiorite for Roman columns. Computer contouring of 1119 magnetic susceptibility measurements at the quarry shows systematic variations, with low readings in the west of the quarry area and higher readings in the east. One hundred and seventy measurements on 62 columns of Mons Claudianus type in Rome and its environs were compared with the quarry readings, using a t-test based procedure. Some columns with distinctively low or high magnetic susceptibility could be provenanced very precisely to areas of about 700 × 700m within the 9km² of Mons Claudianus. Columns with susceptibility in the middle of the Mons Claudianus range could not be provenanced precisely. Results indicate early (first century AD) use of both west and east parts of Mons Claudianus, and contemporaneous use of several parts of the quarry, rather than systematic or sequential opening of the area. Columns found in third-century AD monuments, provenanced to the same parts of Mons Claudianus as earlier material, may indicate reuse of columns in some monuments. Magnetic susceptibility constitutes a portable and non-destructive method capable of provenancing not only to a quarry, but to specific areas within a single quarry.     

A THOUSAND AND ONE COLUMNS: OBSERVATIONS ON THE ROMAN GRANITE TRADE IN THE MEDITERRANEAN AREA

Summary.   Provenancing and archaeological information on Roman granite columns in the Mediterranean area has been collated from a range of published papers by the author and others, together with new analyses for Rome, to produce an integrated dataset comprising 1176 columns. This dataset allows an overview of Roman granite trade in seven regions across the Mediterranean area. Examination of the data indicates that columns made from Troad (Turkish) granite are the most numerous observed overall (compatible with Lazzarini's earlier (2004) observation that this is the most widely distributed type), followed by Aswan, then Elba and Giglio, and Kozak Dağ ( Marmor Misium ). In the city of Rome, Mons Claudianus columns predominate. In geographically peripheral parts of the Roman world (Spain, Israel), granite columns are mainly from local sources, and are generally of smaller sizes than those seen in Rome and Tuscany. Analytical data can be used to suggest multiple extraction sites within some quarries, and have the potential for identification of specific intra-quarry provenance. Dating evidence for primary use of columns from the quarries considered is relatively sparse, but suggests early (first century BC) exploitation of Spanish and Elba granites, while column production at Aswan and Troad persisted into the fourth century followed by reuse within later antiquity, in the fifth and seventh centuries AD.     

Geochemical and Magnetic Provenancing of Roman Granite Columns from Andalucía and Extremadura, Spain

One hundred and fifty two granite columns were examined in eight towns and archaeological sites in Andalucía and Extremadura, Spain, in order to determine the geological provenance of the columns. Three non-destructive methods of characterization were used: mineralogical features, magnetic susceptibility, and concentrations of radioelements (K, U, Th) determined by portable gamma ray spectrometry. Columns were compared with potential sources within Spain and in the Mediterranean area using analogous data previously published and also new data obtained for this work. The majority of the columns are made of Spanish granites, some of which were probably quarried near Mérida. Different chemical types of Spanish granites were used in the northern part of the area studied (Extremadura) and in the southern part (Andalucía). Twenty five columns are not of Spanish granites, but were imported from other sources, namely the Troad and Kozak Dağ areas of western Turkey, the Italian islands of Elba and/or Giglio, and Sardinia (confirming a column previously identified in the literature). The imported columns are found in Itálica, Hispalis (Seville) and Astigi (Écija), and were probably carried along the River Guadalquivir and its tributaries.     

NON‐DESTRUCTIVE PORTABLE GAMMA RAY SPECTROMETRY USED IN PROVENANCING ROMAN GRANITOID COLUMNS FROM LEPTIS MAGNA,NORTH AFRICA*

Portable gamma ray spectrometry (PGRS) provides a non destructive means to analyst quantitatively large artefacts, such as building stones, for the radioelements K. U and Th. Nine Raman granitoid columns at the Leptis Magna Ruins in Windsor Great Park, London, were measured in situ by PGRS. Corrections for the environmental background contribution to the gamma ray flux measured, and for the shape and size of the columns, are described Comparison of the PGRS data with a radioelement data base for Roman granite sources indicates that most of the columns originated in the Troad area of Turkey. Two columns could not be unambiguously provenanced using PGRS alone because there is insufficient difference between radioelement concentrations in certain sources. However, non‐destructive measurements of magnetic susceptibility, used in conjunction with PGRS data, suggest that these two columns originated in the Kozak Daǧ, also in Turkey.     

Marble Pieces in the Romanesque Portal of Glory of the Santiago de Compostela Cathedral. New Data through a Multi-Analytical Approach

ABSTRACT

Probably the most important Romanesque artwork in Spain, the Portal of Glory of Santiago de Compostela is essentially made in granite, the most abundant stone in the NW of Iberia, with the only exception of five marble pieces. Different hypothesis on the origin of these marbles have previously been proposed based on visual assessment or by directly assuming a local source. To shed light on their quarry provenance, a multi-analytical study was performed combining polarized-light optical microscopy, cathodoluminescence microscopy, XRPD, SEM-EDS and stable C and O isotopes. The comparison of the results with the available databases reveals the use of marbles from the Estremoz Anticline (Portugal) in the three exquisitely carved columns strategically placed in the central arcade, whereas the other two pieces are local marbles, illustrating a more complex consumption of this noble material than that initially expected.     

The use of magnetometry and pole-dipole resistivity for locating Nabataean Hawar archeological site in the SW-Jordan

This paper is focused on the joint use of magnetometry and pole-dipole electrical resistivity geophysical methods for assessing their capability in the detection of a prehistoric site in the southwestern Jordan. The survey area, Auara, was built in the first century BC during the Nabataean time and is located in a very arid environment framed on the east and north by white sandstone hills. In order to test this site, a number of magnetic stations and two pole-dipole resistivity traverses were carried out in the investigated area. Magnetic data were taken with one sensor at height of 0.8 m along survey lines spaced 1 m apart. Resistivity measurements were carried out utilizing the pole-dipole array along two profiles. A total of 32 geoelectrical stations spaced 2 m were made along the two profiles. Magnetic method found structure with contrasting physical properties to those of the surrounding material. The archeological interpretation of such structure is in terms of rectangular cistern (pool) with dimensions 26 × 16 m. A probable location of two buried walls spaced 16 m are indicated by low resistivity values.     

康熙三十四年建太和殿大木结构研究

本文在王璞子、傅熹年先生的基础上,通过深入研究《太和殿纪事》所记载的大木尺寸,详细测量、分析太和殿木结构的现状尺寸,得出以下结论1、康熙三十四年所建太和殿平面丈尺是用清尺在明代遗留建筑基址上量度确定的,明清大木侧脚设计有所差异;2、太和殿通檐柱高(柱脚至挑檐枋上皮)等于明间开间;3、金柱高(至上层檐)为通檐柱高的1.5倍;4、上下层斗拱在此基础上深化设计、权衡尺寸,总出挑凑足整尺寸,并通盘考虑以适合檐步举架尺寸;5、按照前后挑檐檩间距的1/3确定屋架正心桁之间的总举架高度。     

A Reconsideration of the Construction Period of the Cruciform Terraces and the Elevated Causeways in the Angkor Monuments,Based on the Magnetic Susceptibility of the Sandstone Blocks*

In this paper, the construction period of the cruciform terraces with columns and the elevated causeways in the Angkor monuments of Cambodia is reconsidered, based on the results of our investigation of magnetic susceptibility and other characteristics of sandstone blocks. From an art‐historical point of view, they are generally considered as modifications in the post‐Bayon style period—the period during the reign of Jayavarman VIII (1243–95 ce ) or later. However, from a lithological point of view, the average magnetic susceptibilities of the sandstone blocks in the cruciform terraces with columns and the elevated causeways are consistent with the rest of the monument. In addition, the characteristics of the sandstone blocks in the cruciform terraces, such as their shape, the orientation of the bedding plane and the stacking method, suggest that they were constructed in the same period as the rest of the monument.     

Fiber-Based Modeling of Circular Reinforced Concrete Bridge Columns

This article presents the application of fiber-based analysis to predict the nonlinear response of reinforced concrete bridge columns. Specifically considered are predictions of overall force-deformation hysteretic response and strain gradients in plastic hinge regions. This article discusses the relative merits of force-based and displacement-based fiber elements, and proposes a technique for prediction of nonlinear strain distribution based on the modified compression field theory. The models are compared with static and dynamic test data and recommendations are made for fiber-based modeling of RC bridge columns.     

Geophysics of Lager Wick forced labour camp,Grouville, Jersey,Channel Islands

Abstract

Three seasons of fieldwork at the forced labour camp of Lager Wick, Grouville, Jersey (2014–2016) employed resistivity, ground penetrating radar (GPR) and magnetic susceptibility to investigate areas of the camp. Resistivity and magnetic susceptibility produced the most useful results, whilst the GPR survey only revealed a modern pipe. The resistivity survey was undertaken in the south-west corner of the former camp close to the entrance gate posts, whilst the magnetic susceptibility survey was undertaken over the remains of one of the barrack huts along the Gorey Road frontage which had been burnt to the ground in 1943. The resistivity survey produced some high resistance anomalies that appear to resemble a demolition layer or a surface on which the huts were constructed. Magnetic susceptibility results showed zones of burning which appear to relate to the remains of one of the burnt huts; excavation revealed a stone/brick surface.     

MAGNETIC SUSCEPTIBILITY THICKNESS CORRECTIONS FOR SMALL ARTEFACTS AND COMMENTS ON THE EFFECTS OF‘BACKGROUND’MATERIALS*

Correction factors for magnetic susceptibility measurements on thin (<c. 50 mm thick > artefacts have been determined experimentally for a KT‐5 Exploranium G S. instrument using prepared blocks of Whin Sill dolerite. The cor rection factor is large (> 1.4) for samples less than 10mm thick, and reduces to 1 01 for samples of 50mm thickness. Measurements on thin samples can also be affected by the backing or substrate material on which they are measured. ‘Background’material, for example, soil or plaster, can contribute significantly to recorded measurements on artefacts, particularly for thin artefacts with low susceptibilities     

Using mineral magnetism to characterise ironworking and to detect its evidence in peat bogs

An experimental approach has been used to establish whether medieval ironworking activity could be identified in peat bogs using mineral magnetic measurements. The research project comprised three elements. First, magnetic susceptibility and remanence properties were obtained for materials from an experimental iron smelt, in a furnace of medieval design, and from material collected during the excavation of the medieval bloomery at Llwyn Du in Coed y Brenin, Snowdonia. Materials sampled and measured included charcoal, aerial dust, roasted bog ore and furnace dust. A second experiment determined whether small amounts of aerial dust released from the furnace could be detected in accumulating peat samples. This was achieved by sprinkling small quantities of dust on to a constructed ’peat core’ that had no detectable magnetic signature prior to the addition of the dust. The application rates used were within the range expected to fall on a peat bog located close to a medieval furnace. Thirdly, mineral magnetic measurements were made on a peat core collected close to the Llwyn Du bloomery. The results confirm that roasted bog ore, aerial dust released from and dust accumulating in the furnace after a smelt, are magnetically detectable. The aerial dust and roasted bog ore produced enhanced susceptibility and remanence signatures in the constructed ’peat core’ experiments. Peaks in IRM_(0.88T) and HIRM were measured in the Llwyn Du peat monolith and appear to correlate with a time when the medieval bloomery was operational. The results presented here suggest that it is possible to identify evidence of past ironworking in peat bogs using mineral magnetic measurements and that the signatures remain well preserved in the peat record even after burial for several hundred years.     

REHABILITATION OF REINFORCED CONCRETE COLUMNS USING CORRUGATED STEEL JACKETING

An experimental investigation was conducted to study the failure mode of existing reinforced concrete columns designed during the 1960s. The effectiveness of using corrugated steel jackets for enhancing the seismic flexural strength and ductility of these types of columns was examined. Three large-scale columns were tested under cyclic loading. The three columns represent existing column, current code-detailed column and rehabilitated column. The variables in the test specimens include the amount of column transverse reinforcement and jacketing of the column. The corrugated jacket was found to be effective in the rehabilitation of the selected existing structure, which does not meet the current seismic code requirements. A method is proposed for the design of the corrugated steel jacket to enhance the lap splice capacity and ductility of the column.     

佛光寺东大殿实测数据解读

结合山西省古建筑保护研究所2004年、清华大学2005—2006年对五台山佛光寺东大殿的手工测绘和三维激光扫描测量,本文借鉴前辈学者对于佛光寺东大殿原始设计尺寸权衡的论述,在今天毫米级精度的测量数据的基础上,得出以下结论:东大殿所用营造尺长298毫米,中五间开间1丈7尺,标准柱高同之;斗拱材宽7寸;斗拱下昂斜度等于总举斜度,基本斜度可描述成“平出47分~(?),抬高21分~(?)”,总举为此基本斜度的11倍,稍间、进深各间尺寸因此定为1丈4尺8寸;中平槫到柱头的高度等于总举高。通过上述的分析与结论,本文强调提高古建筑测绘数据全面性和精度的重要意义及深远的科研前景。     

THE REMANENT MAGNETIZATION OF ANCIENT STRUCK COINS

Magnetic and other measurements are reported for the Guehenno II Gallo-Roman hoard (56-France) which, amongst several thousand Tetricus antoniniani, contains 275 coins struck with the same dies. The orientation of the remanent magnetization is systematically directed outwards from the obverse confirming the identity of the anvil die with the obverse. The magnetization vector is statistically distributed around the vertical axis giving no indication of the geomagnetic inclination at the time of striking. Consequently ancient struck coins cannot be used for dating. The origin of the remanent magnetization was also investigated.     

Images of buried graves in Bayat,Afyon (Turkey) from high-resolution magnetic data and their comparison with preliminary excavations

Dedemezari necropolis, the site of our study, is located in the west of Turkey near Afyon. Archaeologists think that it belongs to the Middle Bronze age. A high-resolution magnetic survey identified buried material highly accurately. In particular, anomalies, which are transformed by the analytic signal method, clarify the observed magnetic anomalies. Magnetic surveying was applied in three different areas in this study. The map of analytic signal-transformed anomalies presented good results on preliminary excavation in trenches A and B. Two types of graves are found in the study area. One is made of clay and the second is carved in the rocks. Shapes of the buried graves are mainly cylindrical and elliptical. Most of the magnetic anomalies are elliptical and reflect the shape of the buried materials. Future excavations in Dedemezari necropolis will be able to be carried out more easily due to the known locations of the buried graves.     

Observations on weathering forms at the Caniapiscau Reservoir, North‐Central Québec, Canada

Weathering forms were encountered during field work in a formerly glaciated shield area in Canada that lies within the Labrador‐Ungava sector of the former Laurentide Ice Sheet. The granite and gneissic granite in the study area display features of surface weathering, such as weathering pits, and of deep weathering, such as an exposed weathering front with associated gravelly saprolite and core stones. Most observations were made along the shoreline of the Caniapiscau reservoir, where wave abrasion since the construction of a hydropower dam has lead to recent exposure of bedrock over extensive areas. The saprolite remnants emphasise the importance of weathering processes in shaping of bedrock relief in the area and together with the other weathering forms indicate restricted glacial erosion. The weathering forms are discussed in the context of glacial erosion and preservation mechanisms.     

On the effect of electron precipitation on the fair-weather electric field

In this short paper we have estimated the influence of the diurnal modulation of the electron precipitation at low and middle latitudes of the South Atlantic Magnetic Anomaly (SAMA) on the fair-weather electric field. We have used simple exponential atmospheric conductivity models, together with the ion production rates determined from balloon and rocket measurements in the SAMA. An upper limit to this influence was also calculated and compared with the normal diurnal variation of the fair-weather electric field due to the diurnal variation of the global thunderstorm activity.     

An assessment of quality in underwater archaeological surveys using tape measurements

The quality of an underwater archaeological survey using 3D trilateration with fibreglass tape measures was established on an underwater test site. A precision of 25 mm was calculated for tape measurements giving a position accuracy of 43 mm. Of the 304 measurements which were made during the tests, 20% were found to be in error.