MATHEMATICS,STATISTICS AND ARCHAEOMETRY: THE PAST 50 YEARS OR SO*

This review of developments in the use of mathematics and statistics in archaeometry over the past 50 years is partial, personal and ‘broad‐brush’. The view is expressed that it is in the past 30 years or so that the major developments have taken place. The view is also expressed that, with the exception of methods for analysing radiocarbon dates and increased computational power, mathematical and statistical methods that are currently used, and found to be useful in widespread areas of application such as provenance studies, don't differ fundamentally from what was being done 30 years ago.     

COMPOSITIONAL VARIATIONS IN AGED AND HEATED PISTACIA RESIN FOUND IN LATE BRONZE AGE CANAANITE AMPHORAE AND BOWLS FROM AMARNA,EGYPT*

This study examines resinous deposits from the interior surfaces of sherds of imported Canaanite amphorae and locally produced bowls from the 18th Dynasty site of Tell el‐Amarna, Egypt. Archaeological evidence indicates that the Canaanite amphorae were used for resin transport, whilst the bowls are associated with burning resin as incense. A number of characteristic triterpenoids identify all the resinous deposits from both vessel types as Pistacia spp. No other resins were observed and there was no evidence of mixing with oils or fats. The composition of the archaeological resins is more complex than that of modern pistacia resin, due to degradation and generation of new components. Experimental heating alters the relative abundance of the triterpenoid composition of modern pistacia resin. One component, the triterpenoid 28‐norolean‐17‐en‐3‐one, is produced by such heating; however, an increase in its relative abundance in ancient samples is not matched by the archaeological evidence for heating. It is therefore not possible to use this component reliably to identify heated resin. However, additional unidentified components with a mass spectral base peak at m/z 453 have been associated with seven (out of 10) bowls and are not observed in resins associated with Canaanite amphorae. It is proposed that these components are more reliable molecular indicators of heating.     

DETECTING MULTIVARIATE OUTLIERS IN ARTEFACT COMPOSITIONAL DATA*

Multivariate statistical analysis of artefact compositional data, usually undertaken to investigate structure in the data, often incidentally reveals the presence of multivariate outliers. Much statistical methodology dealing with the detection of such outliers is not well suited to archaeometric data that, in the event, consist of two or more groups. The paper provides examples to illustrate the importance of detecting and dealing with outliers, and critically examines a range of different approaches to outlier detection. The examples show that cluster analysis, the technique most widely used for this purpose, can fail to reveal outliers clearly identified by other methods.     

STEEL FILES AS CHRONOLOGICAL MARKERS IN NORTH AMERICAN FUR TRADE SITES*

A selection of fragments of steel files excavated from dated western Canadian fur trade sites has been examined metallographically to assess their value as chronological indicators. It was possible in some, but not all, cases to identify the steelmaking process, distinguishing between cementation steel and crucible steel. In other file fragments manganese was detected in the steel both as manganese sulphide inclusions and in solution in the steel matrix. The identification of crucible steel provides a terminus post quem of 1740 for the fragment, and the presence of manganese a terminus post quem of about 1840. The site occupation dates were consistent with the dates deduced from the steelmaking technologies.     

A COMPARATIVE ELECTRON MICROPROBE STUDY OF LERNA III AND IV CERAMICS AND LOCAL CLAY-RICH SEDIMENTS*

This study uses electron microprobe analysis of ceramic artefacts and local day-rich sediments and lithics to help address questions concerning the nature of the cultural change implied by ceramics from Lerna III and IV. It redresses the previous lack of a comparative collection of clay-rich sediments that adequately represents the local variation in clay and temper for the area surrounding Lerna. The resulting comparisons indicate that although they produced stylistically different ceramics, potters from both Lenta phases acquired their clays from the local Lerna area.     

IN VITRO DECOMPOSITION OF BONE COLLAGEN BY SOIL BACTERIA: THE IMPLICATIONS FOR STABLE ISOTOPE ANALYSIS IN ARCHAEOMETRY*

To understand biogenic collagen type I decomposition and to establish how diagenesis may bias archaeometric data, modern mammalian bone was inoculated with a selection of ubiquitous soil bacteria. The presence of exogenous microbial biomass in the inoculated specimens was then checked microscopically prior to collagen extraction. The experimentally degraded bone collagen showed altered amino acid compositions, attributable to the selective breakdown of certain amino acids by the bacteria. While both the bulk collagen extract and the single amino acids exhibited shifts to more negative δ¹³ C-values, enrichment was recorded for general δ¹³ N, and a depletion trend relative to unaltered collagen was observed for individual amino acid δ¹³ N. One explanation for the enrichment of the global δ¹⁵N-values is cleavage of peptide bonds, which leaves ¹⁵ N within the substrate, while the change of ¹³C is mostly due to the altered amino acid composition. On the other hand, possible repolymerization of cleavage products under experimental conditions may also be responsible for the depletion trend of individual amino acid δ¹³C- and δ¹⁵ N-values. This paper discusses the results as a basis for the development of a method for the reconstruction of the isotopic abundance of the original collagen, using the amino acid composition of the degraded product, the contribution of individual amino acids to its global δ-values and of isotope discriminations implied in the microbial decomposition.     

BULK STABLE LIGHT ISOTOPIC RATIOS IN RECENT AND ARCHAEOLOGICAL RESINS: TOWARDS DETECTING THE TRANSPORT OF RESINS IN ANTIQUITY?*

We have applied and refined methods for the determination of bulk hydrogen, carbon and oxygen isotope ratios in modern and archaeological resins. The modern resins have a wide range of isotopic values and vary within the same tree, between individual trees, with species and location. For all isotopes measured, there is a general trend of increasing depletion of the heavier isotope with increasing altitude. There is also a linear trend between depletion of δD and δ¹³C values with increasing latitude; this trend is less clear for oxygen, but is related to the meteoric water line. Two case studies using archaeological resins known or suspected to have been transported in antiquity have been investigated to determine whether isotopic signatures can assist in pinpointing the geographical origin of the resin: Pistacia sp. resin from Canaanite amphorae imported into Egypt from known geographical locations in the eastern Mediterranean during the Late Bronze Age, and Roman amphorae sherds lined with Pinus sp. resin from sites ranging from Britain to the eastern Mediterranean. These results show separate groupings between the two resin types (pine/pistacia) and between the modern/archaeological resins. Some archaeological samples are distinct from the others and the modern resins show differences between geographical areas. However, there are no clear patterns relating the different Canaanite fabrics or the suggested manufacturing site of the Roman amphorae.     

NEUTRON ACTIVATION ANALYSIS OF ROMAN AFRICAN RED SLIP WARE KILNS

Roman African Red Slip ware (ARS) sherds from four ARS kiln sites in modern-day Tunisia (El Mahrine, El Ala, Oudna and Pheradi Maius) have been analysed using instrumental neutron activation analysis. Multivariate statistical methods (including cluster analysis and Manhattan City Block distances), with a dilution correction applied to the data, were used to interpret the concentration data. Reference groups for each of the four kiln sites were established. Both El Mahrine and Oudna were described by two dilution-related groups. These kiln groups were all shown to be compositionally distinct from each other and suitable for use in provenance studies.     

PROVENANCE STUDIES OF ROMAN AFRICAN RED SLIP WARE USING NEUTRON ACTIVATION ANALYSIS

African Red Slip ware (ARS) from Carthage and San Sisto Vecchio (Rome) was analysed by neutron activation analysis. The Carthage tableware was linked with Oudna and the type 1 lamps were probably from a northern ARS/lamp factory other than the sources currently investigated. Two samples were central Tunisian, probably manufactured at El Ala. The San Sisto samples divided into three groups and three outliers of undetermined provenance. Group 1 was central Tunisian, probably from El Ala, and was composed entirely of terra sigillata chiara C forms. Group 2 was of unknown origin within northern Tunisia. Group 3 was the largest subset and most of its constituent samples were associated with El Mahrine. Additionally, four samples were linked with Oudna.