Charcoal reflectance measurements: implications for structural characterization and assessment of diagenetic alteration

Charcoal is a valuable source of archaeological and palaeoenvironmental proxy data. However growing evidence suggests that production conditions can strongly influence post-depositional alteration of charcoal. Consequently, both reconstruction of production temperature and understanding of the potential for diagenetic alteration are of great interest. Here, we use mean random reflectance (Ro_mean) in conjunction with other chemical characterization methods to address these questions. Ro_mean was obtained for a suite of modern analogue charcoal, produced under controlled conditions, and for a series of natural charcoal samples, obtained from archaeological and palaeoenvironmental deposits. Ro_mean proves to be a robust measure to assess formation temperature for samples produced at 400 °C and above, even after exposure to highly oxidizing conditions. Ro_mean is also useful for samples formed between 300 °C and 400 °C. However, if an assemblage of charcoals has been exposed to oxidizing conditions, lower temperature charcoals may be preferentially lost. It is apparent that charcoal produced at lower temperatures is more highly susceptible to chemical oxidation, and that there is a continuum in charcoal degradation potential, dependant upon fuel material and production conditions.     

Polarizing Microscopy Identification of Chemical Diagenesis in Archaeological Cementum

Cementum increment analysis can potentially retrieve relatively complete, high-precision seasonality and mortality profiles from archaeological mammalian tooth assemblages. However, cementum exhibits many similarities to bone in composition, histology, ultrastructure, and even microstructure. Consequently, the mineralized dental tissue may be prone to the same processes of post-depositional chemical alteration that affect bone. This article reviews the issues surrounding chemical diagenesis in cementum and presents a new application to archaeological ungulate cementum of a polarizing microscopy technique that has previously been utilized to identify the effects of chemical diagenesis in archaeological bone and human cementum (Geusa et al., 1999; Gilbert, 1989; Watson, 1975; Zeder, 1978). It is argued that the post mortem leaching of collagen and the diagenetic growth of apatite crystallites can develop into banded features that mimic seasonal cementum increments. This pattern of diagenesis is demonstrated in multiple locations on a macroscopically well-preserved Upper Pleistocene-age archaeological tooth, which was previously interpreted by the author to exhibit biogenic seasonal cementum increments (Stutz, 1993; Stutz et al., 1995). It is suggested that if researchers seek to retrieve seasonality and mortality data from archaeological cementum, the microscopy analysis protocol must include screening of a pilot sample for the frequency and extent of chemical diagenesis.     

Bone Diagenesis and Taphonomic History of the Paso Otero 1 Bone Bed, Pampas of Argentina

Samples of guanaco bone from an archaeological site in the Pampas of Argentina have been analysed to understand the diagenetic profile of the bone assemblages that characterized the taphonomic history of the site. Two archaeological occupations of Paso Otero 1 were investigated, encompassing similar landscape settings, climates, and depositional environments. The time span is a c. 2000 year period from c. 4800 to 2800 years . A total of 30 bone samples taken from both occupations were used to provide a preliminary characterization of the diagenetic pathways at the site. The parameters investigated provide a comprehensive account of how both mineral (hydroxyapatite) and bone protein (collagen) have been altered. In order to compare the two bone assemblages in terms of their diagenetic parameters, multivariate analyses were conducted. Results indicate two different diagenetic profiles in the site, % N being one of the variables that accounts for most of the variation in Paso Otero 1. The diagenetic analyses indicate that protein is less preserved in the bone assemblage from the middle stable landscape. Alternative interpretations of the diagenetic profiles are discussed in light of the taphonomic history of the site, and palaeoenvironmental information of the region. One hypothesis stresses the importance of the role of climate in defining the different diagenetic pathways, and the other the continued action of the combined diagenetic factors along time as the main explanation for the variability in the state of preservation of the bones in Paso Otero 1.     

Assessing mussel shell diagenesis in the modern vadose zone at Lyon's Bluff (22OK520), Northeast Mississippi

This study considers the chemical alteration of archaeological freshwater shell above the water table at the Lyon's Bluff site (22OK520), a single-mound and village complex located in east-central Mississippi, and the changes in trace element concentrations between unfired and fired shell. Thin-section petrography, X-ray diffraction, cathodoluminescence, and scanning electron microscopy analyses were conducted on archaeological shell from four natural layers from Unit 20N20W, over a depth of 80 cm and spanning 450 years. ICP–MS analysis also was conducted on a modern freshwater shell subjected to kiln firing. Microscopy results indicate a pristine aragonite crystal structure in the archaeological samples. ICP–MS data show that certain trace elements within the modern shell maintain their concentration after firing at 500 °C. The broader implications are: 1) that diagenetic alteration does not hinder chemical sourcing of shell at Lyon's Bluff, and 2) that certain trace elements are more reliable than others, namely Sr²⁺, Al²⁺, Ba²⁺, and Mn²⁺, when conducting trace element provenance studies on fired-shell temper.     

Intra-skeletal variability in trace elemental content of Precolumbian Chupicuaro human bones: the record of post-mortem alteration and a tool for palaeodietary reconstruction

This study applies an intra-skeletal sampling strategy to examine post-mortem alteration of archaeological human bone from west Mexico, and to reconstruct ancient diet. Human bone from the Chupicuaro culture (Mexico, Preclassic period) constitutes an ideal material with which to examine subsistence strategies because the specific hydrothermal environment in which the population lived would have provided certain food components (hydrothermal waters and carbonates) with distinct signature in Ca, Mg, F, Li, Sr, Mn, V and U values. Four to ten samples were taken from the long bones of six skeletons. Bone trace element content (Ca, P, F, Mn, Mg, Na, Li, V, Zn, Rb, Sr, Ba, Y, La, Ce, Nd, Th, U) and bone alteration parameters (crystallinity, organic matter and secondary calcite content) were analysed at the intra-skeletal level. Stable isotopic signatures (bone δ¹³C and δ¹⁸O_carbonate) and histological analyses were also performed on a single bone from each individual. Results indicate that all of the skeletons were affected by post-mortem mineralogical, structural and geochemical transformations. Biological bone δ¹³C values seem preserved for most of the individuals but an increase in crystallinity accompanies depletion in bone δ¹⁸O values. The combination of bone alteration parameters with bone elemental content shows that in this very specific context, a widespread dissolution-recrystallisation is unlikely. Of the hydrothermal tracers, Sr, F and Li were of particular interest because their retention in living tissues is related to the amount ingested. The intra-skeletal Li content does not reveal any pattern but Li depletion is not excluded. In contrast, Sr and F show a progressive intra-skeletal diagenetic enrichment likely due to gradual diffusion–adsorption processes. The bones with the lowest concentrations in these elements are assumed to yield the best representative ante-mortem values. The signal extracted from each skeleton, a very unusually high bone Sr, F and Li content, is interpreted as reflecting the consumption of the local hydrothermal products, which are also enriched in these elements.     

Infrared and Isotopic Evidence for Diagenesis of Bone Apatite at Dos Pilas, Guatemala: Palaeodietary Implications

The use of stable carbon isotopic analysis of bone apatite to reconstruct prehistoric diets is hindered by the possibility of diagenetic alteration of carbonate during burial. We examine apatite preservation in Classic Period Maya skeletal remains from Dos Pilas, Guatemala, using Fourier transform infrared spectroscopy (FTIR). We use weight % CO₂evolved from apatite, FTIR carbonate/phosphate absorbance ratios, phosphate peak splitting crystallinity indices, fluoride peaks, and stable oxygen isotopic ratios to identify diagenetic change in apatite chemistry. Isotopically light carbon taken up from burial soil is adequately removed from most Dos Pilas bone by treatment with dilute acetic acid, but more severe alteration cannot be reversed by standard preparation methods. Infrared criteria identify recrystallized apatite in a subset of Dos Pilas burials, that is accompanied by isotopic exchange, and that no longer preserves biogenic δ¹³C. These results illustrate that comparatively recent bone may be diagenetically altered and demonstrate a need for systematic evaluation of mineral integrity in all archaeological bone prior to interpreting paleodiets with apatite δ¹³C.     

The Anthropogenic Use of Firewood During the European Middle Pleistocene: Charcoal Evidence from Levels XIII and XI of Bolomor Cave,Eastern Iberia (230–160 ka)

Human control of fire is a widely debated issue in the field of Palaeolithic archaeology, since it involved significant technological innovations for human subsistence. Although fire evidence has been the subject of intense debate regarding its natural or anthropogenic nature, most authors agree that combustion structures represent the most direct evidence of human control of fire. Wood charcoal fragments from these contexts represent the fuel remains that result from humans’ collection of firewood, which means they can reveal significant behavioural and palaeoenvironmental information relevant to our understanding of Middle Palaeolithic societies. In this work, we present anthracological data derived from combustion structure 2 (level XIII, ca. 230?ka, MIS 7) and combustion structure 4 (level XI, ca. 160?ka, MIS 6) from Bolomor Cave, which are chronologically among the earliest combustion structures found in Europe. The present work discusses how the presence of black pine and / or scots pine in both levels sheds light on the characterisation of the local landscape. Additional analyses focussing on the pre- and post-depositional processes affecting charcoal preservation point to biodegradation patterns. The aim of this work is to provide the first discussion concerning the anthracological data derived from Bolomor Cave in order to contribute to the general debate regarding the use of fire during the European Middle Pleistocene.     

Palaeolimnological impacts of early prehistoric farming at Lough Dargan,County Sligo,Ireland

This study provides a unique method of inquiry for archaeological investigation with an aim to assess the intensity and effects of Neolithic and Bronze Age farming practices at Lough Dargan, northwest Ireland, through a multi-proxy analysis of a lake sediment core. Chironomid (non-biting midge fly) subfossils and lake sediment geochemistry (δ¹³C, δ¹⁵N and C:N ratios) were used to assess changes in limnological conditions through time. The limnological data were compared with macroscopic charcoal concentration and pollen data to examine the potential influence that early farmers had on a freshwater lake system within a prehistorically active catchment. Results from the chironomid analysis show that the first substantial period of agricultural activity in the early Neolithic (c. 3730–3190 BC) resulted in a temporary shift to more eutrophic lake conditions. There is evidence of animal husbandry with substantial levels of animal waste reaching the lake, leaving an imprint in the geochemical record of increased δ¹⁵N values and decreased δ¹³C values and C:N ratios during this time. The chironomid community reverted back to its pre-impacted state c. 3190 BC in response to a period of reduced farming (c. 3390–3000 BC) which eventually led to a distinct lull in activity, with possible cessation of farming from 3000 to 2700 BC. A return to eutrophic conditions coincided with the gradual return of agriculture, with more permanently altered lake conditions dominating from 2400 BC, even during a 250-year period of reduced human activity commencing at c. 1440 BC. Increased sedimentation rate, along with increases in δ¹³C, δ¹⁵N and C:N, the presence of chironomid taxa indicative of erosion, more eutrophic lake conditions and high concentrations of macroscopic charcoal all point to more intensive land use practices during the Bronze Age. Palaeolimnological data exhibited an immediate response to intensified farming during this time, and were especially responsive to pastoral farming due either to scale of activity or proximity to the lakeside. The success of this study demonstrates the effectiveness of palaeolimnological analysis in the investigation of prehistoric farming. This approach will help inform Neolithic and Bronze Age land-use practice and human–environment relations in the region, and highlights the potential for chironomid-based archaeological research.     

Fires at Neumark-Nord 2, Germany: An analysis of fire proxies from a Last Interglacial Middle Palaeolithic basin site

Few sites with evidence for fire use are known from the Last Interglacial in Europe. Hearth features are rarely preserved, probably as a result of post-depositional processes. The small postglacial basins (<300?m in diameter) that dominate the sedimentary context of the Eemian record in Europe are high-resolution environmental archives often containing charcoal particles. This case study presents the macroscopic charcoal record of the Neumark-Nord 2 basin, Germany, and the correlation of this record with the distinct find levels of the basin margin that also contain thermally altered archaeological material. Increased charcoal quantities are shown to correspond to phases of hominin presence—a pattern that fits best with recurrent anthropogenic fires within the watershed. This research shows the potential of small basin localities in the reconstruction of local fire histories, where clear archaeological features like hearths are missing.     

Stable carbon and oxygen isotopic compositions of wood ash: an experimental study with archaeological implications

Wood ash, composed mainly of the mineral calcite, is an important component in many archaeological sites. Identification of wood ash in the archaeological record is often difficult due to mixing of ash with other calcitic components of geogenic origin and/or due to diagenetic changes. A recent empirical study using the stable isotope compositions of carbon (δ¹³C) and oxygen (δ¹⁸O) in wood ash enabled the identification of mixtures of wood ash with geogenic calcite and to follow diagenetic changes due to partial dissolution and re-precipitation of ash in two prehistoric cave sites in Israel. Little however is known about the processes responsible for the isotopic compositions of wood ash in relation to formation at various temperatures and the influence on isotopic composition of ash from a variety of plant species. Here we present an experimental study of wood ash formed by burning three C3 tree species and one C4 desert bush at different temperatures. The results indicate that there are significant differences in the isotopic compositions of carbon and oxygen between wood ash that forms by combustion at a relatively low temperature (500 °C) and at a higher temperature (900 °C). In addition, we show that the isotopic composition of carbon and oxygen in high temperature wood ash approaches equilibrium over a period of several months and that the carbon isotopic composition of low temperature wood ash may reflect the photosynthetic pathway of the burnt woody species. Lastly, we show that the isotopic compositions obtained from wood ash prepared at different temperatures do not reflect a temperature dependent fractionation process, but a mixing line between calcite that formed by low temperature combustion and calcite formed by high temperature combustion which later underwent re-carbonation with atmospheric CO₂. In addition, we suggest that exchange processes may possibly occur during combustion between decomposing calcium-oxalate and atmospheric O₂, CO₂ and CO. The archaeological implications of this study are discussed in relation to identification of wood ash in the archaeological record, identification of fuel sources and burning temperatures, and diagenetic changes expected in karstic cave environments. The method presented here can be applied at any archaeological site.     

Radiocarbon dating and the “old shell” problem: direct dating of artifacts and cultural chronologies in coastal and other aquatic regions

Archaeologists have long recognized the problem of the “old wood” effect in radiocarbon dating charcoal and wood samples, the age of which may be hundreds of years older than their use by humans. Such problems have resulted in significant changes in how most researchers select wood and charcoal samples for ¹⁴C dating, with many now using relatively short-lived carbonized materials for dating. Despite the significant strides made in our understanding of the potential biases of the “old wood” effect, little emphasis has been placed on the possible impacts of dating “old shell” in archaeological deposits. The use of marine shell for ¹⁴C dating is widespread in coastal areas around the world, including a growing emphasis on the dating of individual shell artifacts via Accelerator Mass Spectrometry (AMS). In dating shell artifacts, we have obtained several dates older than associated ¹⁴C dates for short-lived subsistence remains from the same deposits, including great disparities (>10,000 years) and more subtle differences (≥100 years). These discrepancies appear to be due to the use of old shells by humans to make beads and other artifacts, including shells collected from fossil deposits, older archaeological sites, and beaches. The problems caused by the use of old shells to make beads and other artifacts are surmountable through careful sample selection, analysis of multiple ¹⁴C dates on a variety of materials, and proper calibration procedures.     

The Quaternary fossil record of the genus Testudo in the Iberian Peninsula. Archaeological implications and diachronic distribution in the western Mediterranean

This paper explores the presence of tortoise remains and its meaning in Palaeolithic archaeological contexts. We focus on two topics: (1) the presence or absence of the genus Testudo from the Early Pleistocene to the Holocene in SW Europe; and (2) the relationship between Testudo and the palaeoclimatic and palaeoenvironmental conditions diachronically. In order to address this objective, we collected published and unpublished data from different sites on the eastern Iberian Peninsula. The results obtained by this study demonstrate that Testudo hermanni was the only tortoise present in this area until recent times and its presence in archaeological sites is almost always related to anthropic activities. Finally, the disappearance of Testudo from archaeological sites in some areas is related to climatic changes and events that occurred during the last stages of the Pleistocene.     

Microstructural,chemical and isotopic evidence for the origin of late neolithic leather recovered from an ice field in the Swiss Alps

Archaeological leather samples recovered from the ice field at the Schnidejoch Pass (altitude 2756 m amsl) in the western Swiss Alps were studied using optical, chemical molecular and isotopic (δ¹³C and δ¹⁵N of the bulk leather, and compound-specific δ¹³C analyses of the organic-solvent extracted fatty acids) methods to obtain insight into the origin of the leather and ancient tanning procedures. For comparison, leathers from modern native animals in alpine environment (red deer, goat, sheep, chamois, and calf/cow) were analyzed using the same approach. Optical and electron microscopically comparisons of Schnidejoch and modern leathers showed that the gross structure (pattern of collagen fibrils and intra-fibrils material) of archaeological leather had survived essentially intact for five millennia. The SEM studies of the hairs from the most important archaeological find, a Neolithic leather legging, show a wave structure of the hair cuticle, which is a diagnostic feature for goatskins. The variations of the bulk δ¹³C and δ¹⁵N values, and δ¹³C values of the main fatty acids are within the range expected for pre-industrial temperate C₃ environment. The archaeological leather samples contain a mixture of indigenous (from the animal) and exogenous plant/animal lipids. An important amount of waxy n-alkanes, n-alkan-1-ols and phytosterols (β-sitosterol, sitostanol) in all samples, and abundant biomarker of conifers (nonacosan-10-ol) in the legging leathers clearly indicate that the Neolithic people were active in a subalpine coniferous forest, and that they used an aqueous extract of diverse plant material for tanning leather.     

Archaeobotanical inference of Bronze Age land use and land cover in the eastern Mediterranean

Charcoal and charred seeds at five Bronze Age archaeological sites discern ancient land use in the eastern Mediterranean. Seed frequencies of orchard crops, annual cereals and pulses, and wild or weedy plants are used to characterize plant utilization at different archaeological sites on the island of Cyprus, in the Rift Valley of Jordan, and in the Jabbul Plain and along the upper Euphrates River valley in Syria. Seed to charcoal ratios provide proxies to determine the relative usage of dung versus wood for fuel across the ancient Mediterranean landscape. Greater charcoal and lower charred seed values are interpreted to represent a wooded environment, while higher amounts of charred seeds and minimal wood charcoal suggest a much great use of dung as a fuel source. Interestingly, Politiko-Troullia (Cyprus, Cypriot archaeological sites are, by convention, named for the nearest modern village (Politiko), followed by an italicized toponym (Troullia) referring to the plot of land that incorporates the site) has the lowest seed to charcoal ratio, suggesting its residents primarily burned wood and that the landscape surrounding Troullia remained relatively wooded during the Bronze Age. In contrast, villagers at Tell el-Hayyat (Jordan) utilized a mixture of wood and dung, in contrast to Tell Abu en-Ni’aj (Jordan), and especially Umm el-Marra and Tell es-Sweyhat (Syria), where inhabitants relied solely on dung fuel. Comparative analysis and interpretation of seed and charcoal evidence thus illustrates the variety of fuel use strategies necessitated by the dynamic and diverse Bronze Age landscapes of the Eastern Mediterranean.     

Oxygen and strontium isotopes as provenance indicators of fish at archaeological sites: the case study of Sagalassos,SW Turkey

In this paper, we investigate the potential use of oxygen and strontium isotope ratios (δ¹⁸O_p and ⁸⁷Sr/⁸⁶Sr) measured in archaeological fish enamel as provenance indicators. δ¹⁸O_p and ⁸⁷Sr/⁸⁶Sr were measured in a suite of archaeological carp remains recovered from the Anatolian townsite of Sagalassos dated to the Early Byzantine period (AD 450–650) and compared to that of modern fish, river and lake waters from the Anatolian region. We used sequential leaches in weak acetic acid to remove diagenetic Sr from fossil tooth enamel, monitoring the effectiveness of this approach by measuring the Sr/Ca ratios of the leachates via an isotope dilution thermal ionization mass spectrometry method (ID-TIMS). δ¹⁸O_p values mostly excluded a riverine origin. ⁸⁷Sr/⁸⁶Sr ratios of one fish overlapped with the ⁸⁷Sr/⁸⁶Sr signatures of two lakes in the Anatolian region, and at least one lake (Gölcük) could be removed as a candidate owing to a very distinctive ⁸⁷Sr/⁸⁶Sr signature not found in any of the fish remains. Most of the tooth samples analyzed could not be assigned a precise geographical origin since the ⁸⁷Sr/⁸⁶Sr ratios measured in enamel did not match that of any of the local lakes selected as potential origin. This result suggests that carp may have originated from lakes that have not yet been sampled, although this conclusion is not supported by other archaeological evidence. Alternatively, the lack of correspondence between lakes and fish Sr isotope ratios highlights several possible sources of uncertainties including spatial heterogeneity in ⁸⁷Sr/⁸⁶Sr ratio within a lake, the contribution of dietary strontium to the ⁸⁷Sr/⁸⁶Sr ratio of fish tooth enamel, and post-mortem alteration of the tooth Sr isotope signal during fossilization. In spite of the high precision of the strontium isotope analyses and the wide range of variation in the surface waters of the Anatolian lakes and rivers, this method may remain limited to distinguishing between lakes situated in regions of bedrock of very distinct age and geology until these sources of uncertainty are more fully investigated.     

Morphological,chemical and physical changes during charcoalification of wood and its relevance to archaeological contexts

Wood exposed to a heat source can be transformed into charcoal if subject to conditions of carbonisation (in the absence of air) or charring (in restricted air). Charcoal recovered from archaeological sites can yield fundamental information to our understanding of human economic and cultural development over time and (ecological) setting. This work describes the morphological (anatomy, degree of shrinkage), physical (reflectance) and chemical (elemental, molecular composition) properties of charcoal in relation to heat source and wood variables. In this study charcoal and charcoal fuel were experimentally produced whereby temperature (160–1200 °C), time of exposure (2–1440 min), heating rate (high and low) and wood type (angiosperm and conifer) were varied. The results show that charcoal, often described as an inert, black material, has different chemical and physical properties in relation to the investigated variables. By using these different properties it is possible to distinguish between the different types of fires (domestic and industrial) exploited by humans in the past. Morphological analyses and reflectance measurements are effective tools for this purpose and can be used in wood exposed to temperatures of 300 °C and above—temperatures which are relevant to archaeological research. Angiosperm and conifer wood react in different ways when exposed to heat and thus the taxonomic identity of archaeological material needs to be known. Chemical analyses can be used for wood exposed to temperatures below 400 °C whereas elemental analyses of the carbon content can be used for wood exposed to temperatures up to a maximum of 650 °C.     

Seasoned or green? Radial cracks analysis as a method for identifying the use of green wood as fuel in archaeological charcoal

For several years, sociological questions have been central in anthracology. The development of socio-economic approaches based on the recognition of anatomical signatures in wood has made it possible to focus on topics related to firewood use and its management. The presence of radial cracks (RC) on archaeological charcoal is generally interpreted as the result of the burning of green wood. The present study proposes a verification of this theory by the experimental combustion of seasoned and green wood of Scots Pine (Pinus sylvestris L.). Experimenting with this species was a research priority since it was the dominant taxon (representing 80-100% of the charcoal remains) identified in the Palaeolithic European sites under consideration.The experiments were conducted using two different methods: (i) inside a muffle furnace that allowed us to control the combustions, but in which the combustion process is quite different from most archaeological situations and (ii) in an open fireplace, less controllable but closer to the archaeological conditions. The systematic quantification of the number, length and width of the radial cracks (RC) measured on the transversal sections of the experimental samples demonstrates that (i) radial cracks occur independently of the moisture content of the wood before the combustion (on green and seasoned wood); (ii) however, the average number of radial cracks (RC/cm²) allows distinguishing seasoned from green wood; (iii) in the muffle furnace, the size of the RC appeared to be a good criterion for discriminating seasoned and green wood, but this observation was not confirmed by the open-air combustions. Our results clearly show that the appearance of radial cracks is not diagnostic of the combustion of green wood. Nevertheless, the number of radial cracks (RC/cm²) could represent a new method that might help identifying the combustion of green wood in archaeological charcoal samples.     

Pre-screening techniques for identification of samples suitable for radiocarbon dating of poorly preserved bones

Under certain environmental conditions, post-depositional diagenetic loss of bone collagen can severely reduce the number of bones from a particular archaeological site that are suitable for stable isotopic analysis or radiocarbon dating. This study examined nearly 300 bones from 12 archaeological sites across southern England known to yield poor or variable preservation to try to identify one, or more, pre-screening technique(s) that would indicate suitable collagen preservation for radiocarbon dating. The most reliable method was shown to be the percent nitrogen (%N) of whole bone powder, which has an 84% chance of successfully predicting whether or not a bone will yield sufficient (i.e. >1% weight) collagen for dating.     

Three-dimensional Distribution of Minerals in the Sediments of Hayonim Cave,Israel: Diagenetic Processes and Archaeological Implications

The mineral components of the sediments that accumulate in an archaeological site constitute a potentially rich source of information on the diagenesis, and in turn the archaeology of the site. This detailed three-dimensional study of the mineral assemblages in mainly the Mousterian sediments of Hayonim Cave incorporates more than 2100 infrared analyses performed on-site during the excavation, as well as diverse analyses in the laboratory. Three major mineral assemblages are identified: the calcite-dahllite (CD) assemblage, the assemblage comprising mainly montgomeryite, leucophosphite and siliceous aggregates (LMVS), and a highly altered sediment in which the clays have broken down and silica was released. The boundaries between these assemblages were mapped in detail. The overall picture is one of extreme heterogeneity with sharp variations occurring over distances of a few centimetres. The relation between the CD and LMVS assemblages shows that it is a product of post-depositional diagenesis, whereas the altered clay assemblage formed beneath an erosional unconformity. The CD and LMVS assemblages were derived primarily from an accumulation several metres thick of ash deposits produced by humans. Ash is thus shown to be a major component of the sediments of this cave. The distribution of the CD assemblage reflects to a large extent the locations of two active springs/seepages in the cave. The distribution of the CD assemblage also faithfully maps the distribution of bones in the cave, showing that their distribution is a function of preservational conditions and not human activities (Stineret al ., 2001). The conditions that produced the erosional unconformity, also resulted in severe alteration of the clays and other mineral components of these sediments. The erosion process and the fact that the thickness of this altered zone decreases towards the centre of the cave, indicates that the diagenetic driving force was probably climatic. The three-dimensional distributions of the mineral assemblages have a direct bearing on the dating of the cave by thermoluminescence and electron spin resonance.     

Developing baseline data to understand environmental change: a geochemical study of archaeological otoliths from the Coorong,South Australia

Otoliths are calcium carbonate structures found in the inner ear of teleost fish. While they are routinely studied by marine scientists, analyses of otoliths recovered from archaeological sites in Australia and the Pacific have generally been restricted to identification of species and sometimes the fish age. Otoliths can also provide information on the season of catch, and, through trace element analysis, allow the reconstruction of environmental conditions experienced by fish. In this study, we use otoliths from mid- to late Holocene aged archaeological shell middens at the Coorong (South Australia) to examine species present, season of catch, age of fish and environmental conditions experienced by fish. Results demonstrate that the majority of the fish (identified as Argyrosomus japonicus and Acanthopagrus butcheri) were caught in freshwater environments during the warm season, and had grown to an age and size indicative of their having reached sexual maturity. This study provides data indicating fluctuating levels of salinity in the estuary, which are significantly lower than the hypersaline conditions experienced today. Ultimately, this project highlights the usefulness of conducting more detailed investigations of otoliths, including geochemical analyses, to address a wide range of research questions in archaeology and palaeoenvironmental research.