Archaeomagnetic data from three Punic sites in Tunisia

Archaeomagnetic analyses on bricks and slag fragments from kilns have been undertaken. Four new archaeomagnetic directions and two new archaeomagnetic intensities have been reported for three Punic sites in Tunisia. The SCHA.DIF.3K archaeomagnetic model gives the most consistent age estimates, in agreement with the archaeological ages for three of the four analyzed kilns. The archaeomagnetic models appeared to be surprisingly proficient both using archaeodirections and intensities for El Maklouba. The existence of kilns from different chronological archaeological phases (4th–3th century BC and 2nd–3rd century AD) has been confirmed for this site. The archaeological hypothesis that associates the kiln in El Gaala with the neighboring Punic necropolis is compatible with the archaeomagnetic data obtained from the kiln, though a modern use or remagnetisation of the kiln cannot be excluded.     

Archaeological and archaeomagnetic dating at a site from the ager Tarraconensis (Tarragona,Spain): El Vila-sec Roman pottery

A very accurate archaeological dating of a Roman site in NE Spain (El Vila-sec) was made based on the typology of pottery artifacts. Three different phases were identified with activity ranging from the mid-1st century BC to the early-3rd century AD. Analyses of bricks from kilns at El Vila-sec produced data on their stored archaeomagnetic vector. These data were compared with the secular variation curve for the Iberian Peninsula and the SCHA.DIF.3K regional archaeomagnetic model. Both, the reference curve and the model, produced probability distributions for the final period of use for two kilns from the second archaeological phase that were not used during the third phase. At a 95% confidence level, both time distributions cover a wide chronological range including the presumed archaeological age. Both the Iberian secular variation curve and the SCHA.DIF.3K regional model proved to be suitable models for dating the site, although on their own they do not produce a single unambiguous solution. This archaeomagnetic approach could also be applied to neighbouring archaeological sites that have an imprecise archaeological age.     

Archaeomagnetic dating of Dogmersfield Park brick kiln (Southern England)

Archaeomagnetic dating of samples from a brick kiln discovered at Dogmersfield Park has been achieved using both field direction and intensity. Detailed rock-magnetic properties and microwave archaeointensities have already been studied and published elsewhere [Ll. Casas, J. Shaw, M. Gich, J.A. Share, High-quality microwave archaeointensity determinations from an early 18th century brick kiln, Geophys. J. Int. 161 (2005) 653–661]. The archaeomagnetic measurements were assigned time-probability distributions by comparing with predictions from a global model at the sampling site, this procedure suppresses errors arising from relocation to a common central reference location. All three probability distributions consistently indicate the same age (∼AD 1700). Once the probability distributions are combined a narrower probability distribution is obtained, stressing the importance of pursuing combined (directional and intensity) archaeomagnetic analyses. The inferred age is also highly consistent with available historical evidence.     

Combined archaeomagnetic and thermoluminescence study of a brick kiln excavated at Fontanetto Po (Vercelli,Northern Italy)

A combined archaeomagnetic and thermoluminescence study was carried out as part of a rescue archaeological excavation on a kiln discovered during the installation of methane gas pipelines beneath a rice field, along the southern border of Fontanetto Po village (Vercelli province, Italy). A total of 23 independent brick samples have been collected, oriented in situ with an inclinometer; the use of magnetic and sun compass was not possible due to the existence of metallic tubes beneath the kiln and a plastic cover above it. Standard archaeomagnetic procedures have been used for the determination of the archaeomagnetic inclination and absolute geomagnetic intensity. Stepwise thermal demagnetization shows a very stable characteristic remanent magnetization and the calculated mean inclination of the 23 samples is I = 65.3° with α₉₅ = 2.4° and k = 156. Archaeointensity experiments have been performed using the classical Thellier method as modified by Coe, with regular partial thermoremanent magnetization (pTRM) checks. The cooling rate and remanence anisotropy effects upon thermoremanent magnetization (TRM) have been investigated in all the specimens. A total of 19 archaeointensity determinations (at specimen level) that correspond to linear NRM–TRM plots were used for the calculation of the site mean archaeointensity that is 46.4 ± 2.9 μT. Archaeomagnetic dating results show two possible dating intervals for the last 1000 years, calculated at 95% confidence interval: a first one from 1511 to 1614 AD, and a second one from 1768 to 1872 AD. Thermoluminescence (TL) study has been also performed on two brick samples from the kiln's internal wall, using conventional laboratory procedures. According to the thermoluminescence results the kiln's last usage lies between 1796 and 1914 AD. This age is in good agreement with the second dating interval obtained by the archaeomagnetic analysis. The combined archaeomagnetic and thermoluminescence results suggest that the last firing of the kiln could have occurred between the end of the 18th century and the beginning of 20th century.     

A comprehensive numerical chronology for the pre-Columbian cultures of the Palpa valleys,south coast of Peru

Before the arrival of the Spaniards in Peru in 1532, many different societies flourished in the coastal desert of southern Peru. Of these, one of the best known is the Nasca culture (living in the area between about 260 cal BC and 640 cal BC.), which created the famous geoglyphs on the desert floor. In this paper we present a numerical chronology for the cultural development in the valleys of Palpa, in the northern part of the Nazca region, which spans the time from the Archaic Period (starting there around 3760 cal BC) to the Late Intermediate Period (terminating with the arrival of the Spaniards in 1532 AD). The chronology is based on more than 150 ¹⁴C samples collected by our project from well-documented archaeological excavations of 17 different sites in and around Palpa. Thanks to the advanced AMS-¹⁴C dating technique, demanding only few milligrams of organic material, we could focus on samples of plants, like beans, corn, or reed, representing single years of growth or use, and also on delicate materials like straw from clay bricks (adobe) and textiles. All single ¹⁴C dates were combined to cultural phases using a Bayesian statistical model, implementing the a priori information of the archaeological contexts, and adopting the relative ceramic chronologies available for this area.     

Combining an archaeomagnetic and radiocarbon study: dating of medieval fireplaces at the Mühlegasse,Zürich

During the restoration of the Radium cinema located in the old Town of Zürich, a stratigraphic sequence of medieval fireplaces came to light. Based on ceramic finds, a preliminary age of about 1000 AD was assigned. In this paper we show the results from archaeomagnetic and radiocarbon dating, which combined with the stratigraphic information yield a better constrain of the period of use of these fireplaces. Whilst the radiocarbon technique continues to be the most widespread methodology for dating young archeological artifacts, archaeomagnetic dating is becoming increasingly more established in Europe thanks to the increased number of available measurements. A Bayesian model on the period of use of these fireplaces was produced with OxCal, by a combination of magnetic and radiocarbon ages, together with the stratigraphic information. The results show that the fireplaces were probably used during 1 to 2 generations (e.g. 20–40 years each), and are in good agreement with the archaeological context of this site. To make use of the magnetic measurements for future reconstructions of the field, we carried out an additional age model using only the radiocarbon and the stratigraphic information. Although some of the structures show large directional scatter due to poor baking in antiquity, the results confirm the trend of the geomagnetic field around 1000 AD.     

NEW ARCHAEOMAGNETIC STUDIES NEAR XI'AN,CHINA*

Archaeomagnetic and mineral magnetic studies were made of known-age samples from fired structures and sediments from archaeological sites near Xi'an, China. The fired materials retained a stable record of the direction of the past geomagnetic field, which compared well with previous investigations and could contribute to an archaeomagnetic calibration curve. However, discrepancies with documented observations of the field were noted.     

Archaeomagnetic dating of archaeological sites from Switzerland and Bulgaria

Baked materials from three archaeological sites in Switzerland and one in Bulgaria have been examined and dated archaeomagnetically. The detailed rock-magnetic properties of the burnt clay collected have already been studied therefore and have been published elsewhere (Geophysical Journal International 153 (2003) 146). The main aim of this paper is to determine the terminus ante quem for the last firing of the clay collected from pottery kilns or burnt layers. The directional and intensity results of the ancient geomagnetic field corresponding to the time of the structure's last firing are given for each site. These geomagnetic parameters are then compared with reference curves to provide archaeomagnetic dates for the last use of the kilns. Application of archaeomagnetism as a dating tool is only possible for those regions that already have reference curves. Bulgaria is fortunate in having established reference curves covering almost the last 8000 years. Two Swiss sites were dated using only directional results on the basis of existing palaeodirectional results for Switzerland as well as the French directional reference curves. The archaeomagnetic dates of three of the sites were then compared to archaeological evidence and available radiocarbon dates. The palaeointensity data obtained from this study will enrich the existing archaeomagnetic database for western Europe.     

The emerald and gold necklace from Oplontis,Vesuvian Area,Naples, Italy

The present study refers to the characterization of an emerald and gold necklace, dating from the first century AD, found in Oplontis (Torre Annunziata, Naples, Italy), using non-destructive methodologies such as EPMA and microFTIR. Reference samples, from mines known to be active in the Roman Imperial period, were collected and analyzed using the same techniques. Experimental data were also statistically treated in order to classify the emeralds' mines. The comparison of archaeological and reference data allowed to hypothesize, with high probability, an Egyptian origin for the Oplontis emeralds – even if the Habachtal mine cannot be definitively excluded.     

Insights into immigration and social class at Machu Picchu,Peru based on oxygen,strontium, and lead isotopic analysis

The Inca Empire (AD 1438–1532) made common practice of relocating individuals, households and entire communities throughout their expansive realm for different reasons depending on subjects' assigned social class. Reconstructing patterns of immigration at Inca-period sites could therefore permit some estimation of the social class(es) among their constituents, and thereby provide insights into the functional dynamics of Inca political economy. However, this is a difficult endeavor using only archaeological lines of evidence. This study presents oxygen, strontium and lead isotopic results from the well-preserved, well-contextualized skeletal population (N = 74) from the Inca site of Machu Picchu, Peru. Isotopic data are used to reconstruct patterns of immigration at the site, which are in turn used to directly estimate the social class of the population. The resulting isotopic data are widely distributed with no apparent modality, matching the expected distribution of a particular class of nonelite retainers. A novel application of multivariate statistics coupled with geological and faunal isotopic reference data also permits tentative estimation of individuals' regions of origin. This study provides empirical and analytical frameworks for future research in reconstructing residential movement and class dynamics in the late prehistoric Andes.     

Pottery firing temperatures: a new method for determining the firing temperature of ceramics and burnt clay

A new method for determining the maximum firing temperature of ceramics and burnt clay is presented. The technique relies on measuring the magnetic susceptibility on a step-wise re-fired sample. The validity of the method has been tested by determining firing temperatures of two sets of clay samples fired at temperatures ranging from 400 to 1000 °C. Aliquots of the same samples have been studied petrographically by optical microscopy on thin sections and analyzed by powder X-ray diffraction in order to monitor structural and mineralogical changes as a function of temperature. The method is demonstrated on samples from four geographically widely different sites and it is applied to a larger set of ceramics of Late (ca. AD 900–AD 1450) and Inca (ca. AD 1480–AD 1532) periods from the Northwestern Argentine region, dating to a limited period of time prior to the fall of the Inca Empire. The method is shown to be a powerful tool in revealing archaeological information about the change in firing technologies in the pre-Hispanic societies in the Andean area through time.     

A pre-Columbian fisheries baseline from the Caribbean

A pre-Columbian (ca. AD 500–1500) fishery baseline is established for Anguilla, British West Indies from analyses of the remains of captured fishes from five archaeological sites. The zooarchaeological fishery baseline shows pre-Columbian communities captured diverse fishes, many of which are vulnerable to overexploitation. Composition of the captured fish community varies by site underscoring the potential importance of including samples from sites located adjacent to different marine habitats. Analyses of abundance–biomass relationships, community trophic structure, fish size and taxonomic composition indicate the Anguillian pre-Columbian fishery and coral reef ecosystem was healthy and sustainable. By providing a thorough baseline of Amerindian use of fishes on Anguilla, we provide a foundation that aids researchers asking questions about long-term change in Caribbean coral reef fisheries.     

Chemical analyses of the earliest pigment residues from the uttermost part of the planet (Beagle Channel region,Tierra del Fuego,Southern South America)

This paper presents the results of chemical analyses of the organic and inorganic fractions of pigment residues found in three archaeological sites located in the Beagle Channel region, Tierra del Fuego, Southern South America. Twenty-one archaeological samples have been analysed through XRD, SEM–EDX, FT-IR and GC–MS in order to characterise their inorganic colouring components and to search for the presence of organic substances used as binders. Lipids found in some samples are considered as potential binders. These organic components are compared to those found in archaeological sediment samples from the same layers where the pigments have been found, in order to search for potential taphonomic contaminations of the latter by the former. Results show that such contaminations are unlikely, hence the lipid contents are deemed of anthropic origin. The pigment sample results are also compared to data from analyses of natural sediment samples collected in several localities of the Beagle Channel in order to search for potential natural pigment sources. Results show that organic and inorganic components of these sediments are not the same than those present in the archaeological pigment samples, hence the pigment raw material sources have not been yet located. All these data provide for the first time evidence of the existence of ancient activities of pigment sourcing and paint preparation with organic binders which range from 6000 BP to 1900 BP in the southernmost region of the planet.     

Archaeomagnetic versus luminescence methods: the case of an Early Byzantine ceramic workshop in Thessaloniki,Greece

In this contribution, we present a combined archaeomagnetic and luminescence study of archaeologically dated structures. The investigated area is a ceramic workshop comprising several Early Byzantine kilns. Based on (a) the archaeological–anthropogenic stratigraphy of the site, (b) the structural characteristics of the kilns and (c) the few ceramic findings revealed within their context, the operation of this brick and tile factory is approximately dated between the middle of the fifth century until the first decades of the sixth century AD. Three of the well-preserved workshop kilns have been studied archaeomagnetically. The full vector of the geomagnetic field, accompanied by rock magnetic analyses of the studied material, has been defined. The archaeomagnetic study revealed similar directions among the three kilns indicating and confirming their contemporary use. Additionally, several luminescence measurements were obtained on material from the same kilns. The dating of the site was performed with both methods. The archaeomagnetic dating is convergent with the archaeological estimation only when its upper limit is considered. Concerning the luminescence dating, the calculated ages (corrected for anomalous fading and for the ⁴⁰K content) with their standard deviations are convergent with the archaeological estimations for the first kiln, while for the other two, the results seem to be incompatible. The possible factors that provoked this divergence are thoroughly discussed.     

RESEARCH REPORT: MAGNETIC INVESTIGATIONS AND THE AGE OF A MEDIEVAL KILN AT KUNGAHÄLLA (SOUTH‐WEST SWEDEN)*

The results from a magnetic survey and archaeomagnetic investigation of a medieval brick kiln at Kungahälla in Bohuslän (south‐west Sweden) are reported. Detailed magnetic total field and magnetic gradient measurements over known traces of the kiln showed marked local magnetic anomalies of up to 200 nT, revealing the rectangular shape of the kiln remains. Palaeomagnetic investigations of the remanent magnetization of 12 bricks from the kiln floor gave precise definitions of both the direction of the archaeomagnetic field [(D_m, I_m) = (66.7°, 8.8°), k = 655, α₉₅= 1.7°] and the palaeointensity [B_m= 69.0 ± 3.6 µT]. An archaeomagnetic date is obtained by comparing the direction of the archaeomagnetic field found in the kiln with a geocentral dipole‐transformation of the British master‐curve for secular variation. Of two possible archaeomagnetic dates (ad 1280 ± 50 or ad 1480 ± 50), the ad 1280 ± 50 age is in good accordance with the C‐14 ages and archaeological dates as well as with direct historical evidence, whereas a c. 100 years younger TL date appears to be too young.     

A bioarchaeological study of a Western Basin tradition cemetery on the Detroit River

Archaeological monitoring of construction in a Windsor city park on the Detroit River led to the discovery of an isolated cemetery containing the remains of eight individuals assigned to the Late Woodland Western Basin Tradition. At the request and consent of the contemporary First Nation community, tissue samples from five individuals were subjected to radiocarbon dating, mtDNA, and stable isotope analysis to confirm cultural affiliation and further understand the subsistence practices of these people. Radiocarbon dating placed the cemetery at the transition from the Younge phase (AD 900–1200) to the Springwells phase (AD 1200–1400). The stable carbon and nitrogen isotope results provide an unexpected but fuller understanding of Late Woodland Western Basin Tradition subsistence. All individuals were as enriched in carbon as those found on Iroquoian horticulturalist sites to the east, suggesting a very high reliance on maize. Nitrogen isotope values indicate that the protein component of the diet was comprised largely of high trophic level food sources, likely fish. An in situ osteological analysis identified a high number of carious lesions in the visible teeth, also suggesting a diet high in carbohydrates. The mtDNA findings support the antiquity of the Western Basin presence in Northeast North America through genetic links with the Hind Site, an Archaic site in southern Ontario. These results underscore the importance of such studies for providing novel insight into the archaeological histories and lifeways of this distinct Late Woodland tradition. This study also emphazises the need to work with descendant communities to provide them with information on the past that reflects their distinct heritage in the lower Great Lakes region.     

Landscapes of death: GIS-based analyses of chullpas in the western Lake Titicaca basin

The western Lake Titicaca basin is marked by above-ground funerary towers, known as chullpas, located in a variety of geographical contexts and dating to the Late Intermediate Period, or LIP (AD 1100–1450), and Late Horizon (AD 1450–1532). Over the years, interpretations of these tombs have concentrated upon their roles as loci for ancestral veneration and their abilities to perpetuate memory, delineate social ties and territories, and demarcate access to resources. These views share the implicit or explicit assumption that these mortuary structures were intended to be highly visible. Yet this assumption has never been formally tested. By using GIS-based geospatial tools and statistical analysis, this paper investigates the extent to which chullpas surveyed in the western Lake Titicaca basin visually dominated the landscape. These tombs were not positioned in random locations; they exhibit a high degree of clustering and were built in highly visible areas that could be seen from sites of occupation and regions of economic importance such as Lake Umayo. This paper suggests that this landscape of death was deliberately constructed to have an enduring social impact.     

Archaeomagnetic data from four Roman sites in Tunisia

Archaeomagnetic analyses on bricks and slag fragments from kilns have been undertaken. The initial aim of the paper was to constraint the age of four Roman sites in Tunisia (Neapolis, Pheradi Majus, Leptiminus and Sullecthum) using either archaeodirections or archaeointensities. However, the archaeomagnetic models appeared to be only proficient using directions. It has been established that the Neapolis' studied kiln was probably active until the early 6th century AD, whereas the kilns investigated in Pheradi Majus were probably active until the middle 5th century AD. Measured archaeointensities point to higher values than those predicted by the models during the whole range of possible ages for the studied sites.