THE PROVENANCE OF DONKEY MILLS FROM ROMAN BRITAIN

Pompeiian-style (hourglass) grain mills are common at many Roman sites within the circum-Mediterranean countries. Three examples are known from Corfe Mullen, London and Hamworthy in southern Britain. Petrographic examination, chemical and microprobe analyses indicate that the Corfe Mullen millstone and the London donkey mill were imported from central France into southern Britain. The Hamworthy mill should be designated a ‘flat donkey mill’, and represents a recent (post-Roman) import from a volcanic source in Sardinia. There is no evidence of importation of Roman donkey mills from Germany or for transportation of such mills (or stylistic derivatives) north of London.     

PROVENANCING AND ARCHAEOLOGY OF ROMAN MILLSTONES FROM SARDINIA (ITALY)

Summary. Sardinia was an important Roman settlement and trade centre between 238 BC–500 AD and is an ideal site for study of Roman trade. Study of Roman millstones in Sardinia shows that the commonest type is the Pompeian (hour-glass) mill (forty-eight stones studied), with smaller numbers of cylindrical hand querns (sixteen stones studied). Most of these millstones are composed of igneous rocks which include grey vesicular lavas of basic/intermediate composition and a distinctive reddish rhyolitic ignimbrite. There is historical and archaeological evidence for millstone manufacture at six localities in Sardinia. Visual and petrographic study and X-ray fluorescence analysis for major and trace elements of seventeen millstone samples, and fifty rock samples from potential source areas have been used to provenance the igneous rock millstones. The grey vesicular lava millstones have varied sources within the Tertiary-Recent volcanic rocks of Sardinia, while the millstones composed of rhyolitic ignimbrite are from a single source of Tertiary ignimbrite at Mulargia (central west Sardinia). A single hand mill from the north of Sardinia was imported probably from Agde in southern France, and is the only sample composed of non-local rock. Mulargia millstones were widely traded within the western Mediterranean and show a rapid decrease in frequency of occurrence with increasing distance from the source. Sardinia was therefore an important centre of Roman millstone production and a source of millstone trade during the period of Roman settlement.     

MAGNETIC SUSCEPTIBILITY USED IN NON-DESTRUCTIVE PROVENANCING OF ROMAN GRANITE COLUMNS

Magnetic susceptibility provides a rapid, cheap and non-destructive method of in situ characterization of archaeological artefacts containing magnetic minerals, and can be used as an aid to geological provenancing. Three hundred and sixty-three Roman granite columns were measured by this method and results show clear groupings and similarities with potential granite sources in Italy, Turkey and Egypt. Magnetic susceptibility measurements must be made on representative, unweathered surfaces of rocks and artefacts, and corrected for object size and surface relief according to manufacturers’recommendations. In addition, corrections for column curvature have been derived for use with measurements made on columns.     

OBSIDIAN IN THE MEDITERRANEAN AND THE NEAR EAST: A PROVENANCING SUCCESS STORY

Obsidian provenancing studies comprise one of the most productive and successful research programmes of archaeological science. Obsidian characterization has been successful because workable obsidian is homogeneous on a small scale, analysable by a large number of methods, and is restricted to a small number of mainly readily distinguishable geological sources. Analytical, dating, source, and trade studies within the western Mediterranean, central and eastern Europe, the Aegean, and Anatolia and the Near East during the last 30 years or so are reviewed. Research has shown that distributions are mainly separate in the four regions examined, and that obsidian was traded up to 900km in the prehistoric period. Publications on obsidian in the areas under review reached a peak of frequency in the later 1970s and 1980s, but have now decreased in number. This may reflect changing fashions in archaeometric studies, and a current lack of routine application of the provenancing methods developed.     

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 LOW DILUTION,WAVELENGTH-DISPERSIVE X-RAY FLUORESCENCE PROCEDURE FOR THE ANALYSIS OF ARCHAEOLOGICAL ROCK ARTEFACTS

A method is described for the analysis of archaeological rock artefacts which provides major and trace element data. Wavelength-dispersive X-ray fluorescence (WDXRF) analysis of 2:1 fusion beads permits the accurate and precise measurement of a wide range of elements. Accuracy and precision are nominally 1-5% for elements having concentrations above 3 times the detection limit. The method requires a much smaller sample size than conventional WDXRF procedures and has been successfully used to characterise early millstones; a number of other applications in archaeology are suggested here.     

PRESELI DOLERITE BLUESTONES: AXE-HEADS, STONEHENGE MONOLITHS, AND OUTCROP SOURCES

Summary.   Chemical compositions and magnetic susceptibility data were compared for 12 dolerite bluestone implements including axes, axe-hammers and battle-axes, 11 Stonehenge monoliths (chemical data only), and potential source outcrops in Preseli, South Wales. Most of the studied artefacts are of spotted dolerite, a small number being unspotted dolerite. Bivariate graphs, discriminant analysis and t-tests were used singly and in combination to show, respectively, that the implements found at sites in England are mainly similar to Stonehenge monoliths, while the implements found in Wales have a variety of compositions and are much less similar to Stonehenge monoliths. The dichotomy between English and Welsh dolerite bluestone implements could be explained by exploitation of different Preseli outcrops or erratic assemblages derived from them. A small number of spotted dolerite implements have previously been shown to have chemical compositions atypical of and marginal to Preseli, suggesting the possibility of a source of spotted dolerite outside Preseli. Previously published analytical data in combination with the new implement/outcrop comparisons presented in this paper support derivation of the majority of analysed Stonehenge monoliths at one particular outcrop within the group of four identified by Thorpe et al. 15 years ago. Analysis of all the extant bluestone monoliths at Stonehenge (now possible using non-destructive methods) would allow progress in identifying monolith outcrop sources, and in understanding the links with the bluestone axe trade.     

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.     

MILLSTONE PROVENANCING USED IN TRACING THE ROUTE OF A FOURTH-CENTURY BC GREEK MERCHANT SHIP

A Greek merchant ship carrying a cargo of millstones, amphorae and bronze vessels was wrecked at Sec, off Mallorca, Spain. in about 375-350 BC. Geochemical provenancing of the millstones helps in reconstructing the route of the ship and complements evidence from the amphorae. Thirty-eight lava hopper-rubber millstones and one Pompeian-style rotary mill from the ship were sampled for provenancing. The hopper-rubbers are mainly of basalt from the island of Pantelleria off North Africa in the Sicilian channel, one is from Nisyros off the Anatolian coast, and the Pompeian mill is of ignimbrite from Mulargia in Sardinia. The hopper-rubbers are the most westerly examples known in the Mediterranean. and the Nisyros mill represents the first proven instance of millstone transport between the east and the west Mediterranean. The occurrence of the Pompeian mill in a fourth-ceniury BC context is evidence of the use of this type a century earlier than previously thought. The Nisyros mill was probably taken on board at the start of the ship's voyage in the eastern Mediterranean, the Pantellerian mills may have been collected partly as ballast at Pantelleria, and the Mulargia mill was probably picked up at Carthage.     

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.