BAYESIAN ANALYSIS OF PLEISTOCENE CHRONOMETRIC METHODS*

Bayesian analysis of radiocarbon dates on Holocene archaeological sites has become well established. Application to Pleistocene sites dated by multiple techniques would be advantageous. This paper develops the necessary mathematical apparatus in the form of likelihoods for luminescence dating, and uranium‐series dating, and considers the possibility for amino‐acid racemization dating. Application of the new methods is illustrated using the stratigraphic sequences of dates from the sites of Saint‐Césaire and La Chaise‐de‐Vouthon. For application to amino‐acid racemization dating, fuller publication of data is found to be required.     

Rubidium hydroxide polyethylene glycol crown ether in the conservation of old master paintings*

The development of new, gentler methods for the conservation of Old Master paintings, with an emphasis on the removal or thinning of deteriorated varnish, is of high priority. In the course of the deterioration process, oxidative attacks lead to progressive formation of carboxylic acid groups, while many ester bondings are expected to be weakened. A stable RbOH polyethylene glycol complex was a promising tool to react with these moieties and to successfully break down the polymeric varnish layer. The remnants were easily wiped off mechanically. Control studies employing ⁸⁶RbOH and ¹⁴C polyacrylate showed the complete absence of residual cleansing components on the paint surface.     

Patterns of Diagenesis in Bone II: Effects of Acetic Acid Treatment and the Removal of Diagenetic CO3

Archaeological bones of varying preservation have been treated with 0·1 M acetic acid in order to investigate the effect on structural and chemical alterations caused by diagenesis. Acetic acid is commonly used as a “cleaning agent” for removing diagenetic carbonate from bone and enamel, in an attempt to recover original, biogenic signals for use in dietary and¹⁴C dating studies.Diagenetic parameters were measured before and after treatment on a range of archaeological bones with good and bad preservation. Histological preservation defined the behaviour of the correlating parameters, where correlation coefficients between carbonate content and crystallinity, microporosity and macroporosity increased significantly after treatment. For histologically well preserved material, acetic acid is effective at returning carbonate content to around that of modern bone. Where bone is extensively damaged by micro-organisms, “loose” diagenetic material can be removed, but a fraction largely composed of hypermineralized bioapatite remains, which, we believe, cannot be reliably used to obtain accurate biological signals.     

A NEW METHOD FOR EXTRACTION,ISOLATION AND TRANSESTERIFICATION OF FREE FATTY ACIDS FROM ARCHAEOLOGICAL POTTERY

This paper presents evidence for increased recovery of organic residues from archaeological pottery through use of a microwave‐assisted liquid chromatography protocol. C_16:0 and C_18:0 saturated fatty acids were obtained from archaeological potsherds recovered from nine Neolithic settlements in the Middle East dating between 4700 and 7300 cal bc , including materials that had not produced evidence for the survival of any lipid species through use of ‘conventional’ solvent extraction techniques. Compound‐specific isotopic analyses of C_16:0 and C_18:0 fatty acids in potsherd extracts subsequently revealed δ¹³C/δ¹²C compositions consistent with modern subcutaneous fats of wild boar and goats pastured on lands adjacent to the Jordan Valley, and residues from a modern pottery vessel used in the manufacturing of butter, cheese and yogurt in central Turkey. These results are presented as an illustration of capabilities of the microwave‐assisted recovery protocol. The reclamation of saturated and unsaturated fatty acids from archaeological pottery fragments recovered from a number of the earliest ceramic horizons in the Middle East is herewith reported, and the extraction methods and instrumental analytical techniques are described.     

A COMPARISON OF METHODS FOR ESTABLISHING FATTY ACID CONCENTRATION GRADIENTS ACROSS POTSHERDS: A CASE STUDY USING LATE BRONZE AGE CANAANITE AMPHORAE*

Canaanite amphorae fragments in fabrics believed to be associated with the bulk transport of vegetable oils from the fourteenth‐century BC site of Amarna, Egypt, have been examined. A comparison is made between solvent extraction, saponification and the use of TMTFTH (m‐trifluoromethylphenyl)trimethylammomum hydroxide, used here for the combined extraction and derivatization of ceramic‐absorbed organic residues. Extracts were studied using gas chromatography and gas chromatography‐mass spectrometry. The extraction of fatty acids from small ceramic samples has established concentration gradients of absorbed organic matter from the inner to the outer surfaces of the sherds.     

Correlation BetweenC Ages and Aspartic Acid Racemization at the Upper Palaeolithic Site of the Abri Pataud (Dordogne, France)

The Upper Palaeolithic site of the Abri Pataud (Dordogne, France) has been the subject of numerous¹⁴C age determinations which cover the period from 20,400±450 years (OXA-373) to 34,250±675 years (Grn-4507). The racemization ratios of aspartic acid have been determined in 26 fossil bones. The bones are present in two different sedimentary surroundings: levels (fine deposits with numerous artefacts and fossil bones) and “éboulis” (coarse deposits derived from the neighbouring limestone cliff). Racemization ratios for total aspartic acid have a poor correlation with¹⁴C ages (respectivelyr²=0·59 and 0·82 for the two environments) but apparent racemization rates are clearly dependent on the type of deposits (levels: K=4·4×10⁻⁶year⁻¹; éboulis: K=9×10⁻⁶year⁻¹).Racemization ratios of aspartic acid in a high molecular weight protein fraction (>10,000 Da) correlate much better with¹⁴C ages (r²=0·999) for the samples from the levels (k=2·1×10⁻⁵year⁻¹). From this regression line we estimate ages for two Aurignacian levels: level 6≈29,560 years and level 9≈30,440 years .It is noteworthy that none of the regression lines intercepts the origin. Racemization of aspartic acid appears to occur only after a delay of many thousands of years. This phenomenon could be the result of a coupling between the degradation of proteins and the racemization of amino acids.     

THE AMINOCHRONOLOGY OF MAN‐INDUCED SHELL MIDDENS IN CAVES IN NORTHERN SPAIN*

Here, we provide the first report on the ages of 54 archaeological levels in 38 caves in northern Spain by means of the aspartic acid d /l ratio measurements in Patella shells, with good results. For this purpose, we developed an age calculation algorithm that allows the numerical dating of deposits from other archaeological localities in the area and nearby regions. We conclude that the sample size—that is, the number of shells analysed within a single level—reinforces the importance of analysing numerous specimens per horizon and the understanding of the time‐averaging concept. The ultrastructure of different species of Patella shells was also studied, showing calcite in their apexes and aragonite at their margins.     

Identifying Chemical Activity Residues on Prehistoric House Floors: A Methodology And Rationale For Multi‐Elemental Characterization of a Mild Acid Extract of Anthropogenic Sediments

Archaeologists have employed sediment chemistry in site prospection for nearly a century. For example, phosphorus is a good indicator of human occupation, because it is a generic indicator of human activity. Recently, multi‐element studies of sediments have successfully identified specific activity areas by analysing other elements in addition to phosphorus. To reach its full potential, however, sediment chemistry must be undertaken with an understanding of how these residues are formed and of the chemical indicators that can be used to identify specific activities. Methodologies that optimize the extraction of specific residues must be employed. Not to do so is a naïve application of the technique.     

Inductively coupled plasma emission spectroscopy and Postclassic Petén slipped pottery: an examination of pottery wares,social identity and trade*

ICP–ES analysis of the clay pastes of Postclassic (c. ad 850–1524) slipped pottery from the central Petén lakes region establishes chemical composition groups that provide information concerning manufacturing traditions and trading patterns. These data demonstrate that manufacturing traditions and trading patterns change throughout the Postclassic period, reflecting possible socio‐political alliances as different ethnic groups migrated to and from the Yucatán peninsula into the central Petén lakes region. The chemical composition groups also demonstrate that some manufacturing traditions imitate those from the Late Classic period and that some clay sources were used throughout the Postclassic period for multiple ceramic groups.     

Hydrological monitoring of an alluviated landscape in the lower Great Ouse valley at Over,Cambridgeshire: the quarry restoration phase

Abstract

This paper sets out the results of the last phase of the hydrological monitoring programme conducted at the Hanson Over quarry in Cambridgeshire, during the first full year (March 2004 to March 2005) in which the area of the first phase of gravel extraction was reinstated as reed beds under the management of the Royal Society for the Protection of Birds. It follows on from the studies of the pre-extraction and extraction phases, both published previously in Environmental Archaeology (French et al. 1999; French 2004). It is reassuring to report that the groundwater table in the formerly quarried area and the landscape immediately upstream and downstream has ostensibly been restored to pre-extraction levels, along with a return to previous pH, conductivity, redox and dissolved oxygen values in the groundwater system. Significantly, the continuing gradual fall in groundwater levels observed beyond 500 m from the quarry face for a distance of at least 1·5 km was seen to be arrested, although these had not quite recovered to pre-extraction levels downstream to the northeast. In addition, the soil moisture within the alluvial overburden and the buried palaeosol has also almost returned to pre-extraction levels. This indicates that the clay bunding of the formerly quarried areas acts as an effective barrier against further water abstraction, both inside and outside the sealed area, and allows the natural aquifer to begin to return to its previous levels of influence.

The study dramatically indicates that both the mineral operator, drainage authority and archaeological curator need to collaborate from the outset of any quarrying operation to ensure the continuing maintenance of the groundwater and soil moisture system regardless of how well the combined gravel and water abstraction processes are conducted, and how successful the post-quarry conservation is. As every site's landscape dynamics contribute to its individual hydrological setting, each case is different and requires tailored monitoring programmes to protect the archaeological and palaeo-environmental record from the adverse effects of water abstraction associated with development schemes.