Building a high-resolution chronology at the Maya archaeological site of El Palmar,Mexico

This paper discusses how detailed analyses of archaeological contexts and macrobotanical remains are critical for building a high-resolution chronology in archaeological research. While the application of Bayesian modelling has improved chronology-building significantly, archaeologists have sometimes neglected different dates recovered from the same depositional layer without further scrutiny. Based on 78 radiocarbon samples, this problem is challenged by building a high-resolution chronology of the Guzmán Group, a small plaza compound of the ancient Maya city of El Palmar, Mexico. The results permit a deeper understanding of relationships between dynastic interactions and the emergence of non-royal elites in Classic Maya society.     

Applying new approaches to modeling diet and status: isotopic evidence for commoner resiliency and elite variability in the Classic Maya lowlands

Classic Maya states were characterized by a high degree of socioeconomic stratification. This paper investigates the degree to which status, as defined by grave goods and tomb construction, influenced dietary patterns of elites and commoners throughout the Classic Period (200–900/1000 AD) of the southern lowlands. We compile a database (N = 102) of previously-published stable isotope ratios (δ¹³C collagen, δ¹³C apatite, and δ¹⁵N collagen) from Maya bone mineral and collagen, and interrogate these data through two new isotopic modeling techniques: a simple carbon isotope model ( Kellner and Schoeninger, 2007; Froehle et al., 2010) and a multivariate isotope model ( Froehle et al., 2012). We find that Maya elite diet varied significantly through time in terms of maize consumption and trophic level, while commoner diet remained remarkably stable. These findings provide new information relevant to studies of ancient Maya class structure and to studies of subsistence strategies of the pre-Columbian Americas.     

A Bayesian C chronology of Early and Middle Bronze Age in Sicily. Towards an independent absolute dating

This paper proposes a Bayesian model for the ¹⁴C chronology of Sicilian Early and Middle Bronze Age, with a specific focus on the northeastern sector of the island. Building on the available ¹⁴C determinations, the model allows addressing a number of chronological questions left open in literature, making a first step towards an independent absolute chronology. The analysis put the start of the earlier part of Early Bronze Age (Capo Graziano 1-Casa Lopez phase) between 2400 and 2175 cal BC, and the end at about 1960 cal BC. The advanced stage of the same period (Capo Graziano 1-Filo Braccio phase) is likely to have started and ended around 1960 and 1730 cal BC respectively. The model indicates that the time slot with the highest posterior probability for the start of the Middle Bronze Age–Milazzese (Portella phase) is between 1490 and 1460 cal BC. This turns up to be earlier than held to date. Notably, the model enables for the first time to bracket the development of the later stage of Early Bronze (Capo Graziano 2-M. di Capo Graziano phase) between 1730 (end of Filo Braccio phase) and 1490/60 cal BC (start of Middle Bronze Age–Portella phase). The latter date is earlier than usually held for the end of Capo Graziano 2. The existence of a narrow gap between the end of the latter and the start of Middle Bronze Age-Portella phase is tentatively proposed only on stratigraphic grounds. Further, the analysis enables for the first time to pinpoint and quantify the lag that is likely to have existed between the start of those Sicilian prehistoric phases and the appearance of Late Helladic imports. The comparison with the Aegean ¹⁴C Bayesian chronology indicates that a time lag (about 45 yr) is likely to have occurred between the start of Capo Graziano 2 and of the Late Helladic period. A time lag between 20 and 70 yr is likely to have existed between the start of the Sicilian Middle Bronze Age and of the Late Helladic III. Arguments tentatively supporting the narrower interval are also discussed.     

New radiometric dating of water management features at the prehistoric Purrón Dam Complex,Tehuacán Valley,Puebla, México

Recent investigations at the prehistoric Purrón Dam Complex in the Tehuacán Valley of southern Puebla, México applied radiometric dating to more securely date the complex. Ceramic-based dating in the 1960′s placed the Dam's origin to the Formative Period. While Formative Period origins are widely accepted, the chronology lacks resolution and direct dates. Samples from impounded sediments behind the dam and from prehistoric canal fill were dated through Optically Stimulated Luminescence (OSL) as well as both standard ¹⁴C and accelerated mass spectrometry (AMS) assays. These samples directly date the functioning of the water management features within the complex. The results confirm the Formative Period origins of the Purrón Dam, and offer new insights into the construction and functioning of the dam and irrigation system.     

Radiocarbon dating of prehistoric hearths in alpine northern Sweden: problems and possibilities

The chronology of prehistoric Sami settlement sites has previously been established by conventional radiocarbon dating of bulk charcoal samples associated with hearths from sunken hut floors (stállo-foundations). Here we present results of a comprehensive dating exercise of stállo-foundations in the alpine area of northern Scandinavia using Accelerator Mass Spectrometry (AMS) radiocarbon dating of charcoal. Over a 3 km² study area, AMS calibrated ages of hearth charcoal from 22 stállo-foundations across 12 sites securely date these features to between cal. AD 640 and AD 1180. Only small variations in age were found between charcoal samples from different areas of a given hearth. Statistical analysis of all the charcoal AMS radiocarbon dates obtained reveals that 12 stállo-foundations across nine sites are contemporaneous and date to the Viking Period (AD 800–AD 1050). The tightly constrained AMS-based chronology of stállo-foundations contrasts with the existing chronology based on conventional radiocarbon analysis, which places these features within a significantly greater time-frame of between AD 600 and AD 1900, with most dates ranging between AD 800 and AD 1350.This discrepancy is likely to result from the necessity of collecting composite hearth charcoal particles, which may originate from different phases of occupation, in order to achieve the required final carbon content for conventional radiocarbon analysis. We argue that the new AMS-based radiocarbon chronology of stállo-foundations presented here supersedes the existing chronology based on conventional (Gas Proportional counting) radiocarbon analysis and we advocate the use of AMS radiocarbon dating in future hearth investigations.     

Holocene land-use evolution and associated soil erosion in the French Prealps inferred from Lake Paladru sediments and archaeological evidences

A source-to-sink multi-proxy approach has been performed within Lake Paladru (492 m a.s.l., French Prealps) catchment and a 6-m long sediment sequence retrieved from the central lacustrine basin. The combination of minerogenic signal, specific organic markers of autochthonous and allochthonous supply and archaeological data allows the reconstruction of a continuous record of past human disturbances. Over the last 10,000 years, the lacustrine sedimentation was dominated by autochthonous carbonates and the watershed was mostly forest-covered. However, seven phases of higher accumulation rate, soil erosion, algal productivity and landscape disturbances have been identified and dated from 8400 to 7900, 6000 to 4800, 4500 to 3200, 2700 to 2050 cal BP as well as AD 350–850, AD 1250–1850 and after AD 1970. Before 5200 cal BP, soil erosion is interpreted as resulting from climatic deterioration phases towards cooler and wetter conditions. During the Mid-Late Holocene period, erosion fluxes and landscape disturbances are always associated with prehistorical and historical human activities and amplified by climatic oscillations. Such changes in human land-used led to increasing minerogenic supply and nutrients loading that affected lacustrine trophic levels, especially during the last 1600 years. In addition, organic and molecular markers document previously unknown human settlements around Lake Paladru during the Bronze and the Iron Ages.     

Assessing the applicability of portable X-ray fluorescence spectrometry for obsidian provenance research in the Maya lowlands

Recent innovations in portable energy-dispersive X-ray fluorescence (PXRF) spectrometry have increased its utility for the geochemical characterization of obsidian artifacts for archaeological provenance research. However, concerns over the utility of PXRF instrumental analyses have been raised, focused on the validity and reliability of the geochemical data produced. Here we adopt the framework of Richard Hughes (On Reliability, Validity, and Scale in Obsidian Sourcing Research, 1998), whereby reliability addresses instrument stability and issues of measurement while validity pertains to an instrument’s ability to discern geochemical source provenance. This is done in order to test the utility of PXRF instruments for archaeological provenance research. k-Means cluster analysis was used to test the accuracy of PXRF through statistical comparison of data acquired via laboratory and portable energy-dispersive XRF instruments. Multivariate analysis was employed to demonstrate obsidian source representation at two Classic Maya archaeological sites in southern Belize – Uxbenká and Ek Xux – and to test the validity of data obtained from a PXRF instrument in answering archaeological research questions pertaining to regional interactions between lowland Maya polities. Results suggest that portable XRF instruments produce internally consistent results. However, data acquired from a PXRF instrument are not statistically equivalent to other XRF instruments. This is to say that while PXRF is not a reliable technique, it is valid for questions pertaining to geochemical source representation.     

New dates from Ushki-1, Kamchatka,confirm 13,000 cal BP age for earliest Paleolithic occupation

For many years cultural layer 7 at the Ushki sites, Kamchatka was considered to represent the earliest human occupation of Beringia, because four radiocarbon dates indicated an age of 16,000–17,000 calendar years ago (cal BP). In 2003, however, Goebel et al. reported that layer 7 more likely formed only 13,000 cal BP, nearly 4000 years later than N.N. Dikov, the site’s primary excavator, originally reported. Some researchers have downplayed the significance of the new dates, continuing to regard Dikov’s early dates as evidence that at least some of the hearth and dwelling features previously excavated at Ushki-1 date to as early as 17,000 cal BP. Here we present four new radiocarbon dates (and two previously unpublished dates) on curated charcoal from hearth features excavated at Ushki-1 more than 20 years ago. They indicate that these hearths and associated dwelling features date to about 13,000 cal BP. We now know 15 radiocarbon dates on charcoal from a variety of features and profiles across Ushki-1 and Ushki-5 that indicate the age of layer 7 is about 13,000 cal BP. We discount the four 16,000–17,000 cal BP dates, first, because two of them came from a deeply dug human burial pit and were likely secondarily introduced into the burial; second, because provenience data for the other two dated samples were never reported and do not exist in the records of the radiocarbon laboratories that produced them; and, third, because sediments immediately underlying layer 7 at Ushki-1 are only a few centuries earlier than 13,000 cal BP, providing an important lower-limiting age for the layer-7 occupation. We conclude that the age of all of the layer-7 features at Ushki-1 and Ushki-5 should be considered to be about 13,000 cal BP, at least until the earlier obtained old dates of 16,000–17,000 cal BP can be replicated.     

A radiocarbon chronology for Sāmoan prehistory

The corpus of radiocarbon dates for Sāmoan archaeology has grown exponentially since the pioneering work of Green and Davidson in the 1960s, enabling us to re-analyze the archipelago's cultural chronology. A reliable and valid radiocarbon chronology forms the basis for describing and explaining cultural variability and change in the central Pacific. Towards that end, in this paper we compile the available radiocarbon dates from published and unpublished (“grey literature”) sources. We critically evaluate 236 radiocarbon dates following a chronometric hygiene protocol to identify the most secure and reliable age estimates. We accept 147 dates (62.3%) as a means of addressing two significant issues for Sāmoan prehistory: (1) the chronology of settlement and human expansion across the archipelago pre-2000 cal BP, which relates to issues of Lapita colonization, and the effect of island geomorphology on settlement; and (2) analysis of the so-called “Dark Ages” (ca. 1500–1000 cal BP), a period relevant to issues of social complexity and East Polynesian settlement. Our research highlights the need for a rigorous sampling protocol for radiocarbon dating.     

Stratigraphy and geochronology of La Playa archaeological site,Sonora, Mexico

La Playa archaeological site in northern Sonora, Mexico contains a long record of human activity that includes the Paleoindian period (terminal Pleistocene) and much of the Holocene. The size and complexity of La Playa has discouraged a systematic characterization of its stratigraphy and geochronology, a deficiency we redress in the study. We distinguished seven stratigraphic units ranging in age from >44,570 to 400 cal yr B.P. using ¹⁴C dates from charcoal and terrestrial gastropods found mostly in archaeological features. All of the buried (in situ) cultural remains are contained in Units B (4690–1580 cal yr B.P.) and C (1010–400 cal yr B.P.) and represent overbank deposition from the nearby Rio Boquillas. Occupation at the site peaks in Units B₄ and B₅, corresponding to the Cienega phase (2800–1800 cal yr B.P.) of the Early Agricultural period. This period coincides with the growth of early agricultural villages in the region and is marked at La Playa by thousands of archaeological features including roasting pits, human burials, and extensive canal irrigation systems. The presence of semi-aquatic and aquatic snails demonstrates that water was present year round in the canal systems constructed during this period. Stable and radiometric isotopic evidence suggests that early agriculturalists diverted ground water over several kilometers from the nearby Rio Boquillas. The extensive Cienega phase occupation ended after about 1700 cal yr B.P. with deep erosion of the site, an event also visible in alluvial records in southern Arizona that marked the end of the Early Agricultural period and significant changes in settlement organization in the region.     

Spatial Autocorrelation and the Classic Maya Collapse: One Technique, One Conclusion

A pair of articles appearing recently in this journal (Whitley & Clark, Journal of Archaeological Science12, 377-395, 1985; Kvamme, Journal of Archaeological Science17, 197-207, 1990) apply spatial autocorrelation analysis to the distribution of terminal long-count dates from southern Lowland Classic Maya monuments. The authors employ similar techniques yet arrive at contradictory conclusions regarding the presence of geographical patterning in the collapse of the Classic Maya civilization in this region. Kvamme's contention, however, that Whitley & Clark conducted an inappropriate analysis and arrived at an erroneous conclusion is unsubstantiated. Both articles present appropriate analyses and report results which support the presence of spatial patterning in the Lowland Maya dates.     

New age constraints for hominid footprints found on Jeju Island,South Korea

In 2004 numerous hominid footprints, along with diverse animal footprints, were found in the Late Quaternary strata of Jeju Island, South Korea. However, the age of the sediments in which the footprints were found is still controversial. Previous age estimates included radiocarbon ages of ca. 15,000 yr BP (Late Pleistocene) and quartz optically stimulated luminescence ages of ca. 7000 yr BP (mid-Holocene). In this study we report on 11 AMS ¹⁴C dating results from a new set of samples collected from the footprint-bearing strata and from associated sediments. Despite some variations and age reversal, all samples collected from the footprint-bearing strata yielded ¹⁴C ages of late Pleistocene. These ages are comparable with previous radiocarbon dating results. Furthermore, the presence of the proboscidean footprints attributable to woolly mammoths in the footprint-bearing strata supports the radiocarbon dating results. Based on the new radiocarbon dates and the presence of the alleged mammoth footprints, the age of the hominid footprints found at Jeju Island is thought to be late Pleistocene (about 19,000–25,000 cal yr BP). Therefore, this is the second discovery of hominid footprints dated to the Pleistocene age in Asia, and the first to be discovered in Korea.     

Raman microprobe analysis of stucco samples from the buildings of Maya Classic Copan

Micro-Raman spectroscopy has been applied to painted stucco samples from three buildings at the Maya site of Copan, Honduras. The buildings, Clavel (AD 450–550), Ani (AD550–650) and Structure 10L-22 (AD730,) date from three phases of the Classic Period (AD400–820) acropolis construction. The red pigment has been identified as haematite and the stucco as a mixture of calcite particles dispersed throughout a calcite based lime wash stucco. The physical structure of the stucco changed through time, indicating a refining of production techniques over this period. By combining Micro-Raman spectroscopy with other micro-ATR infrared spectroscopy and environmental scanning electron microscopy a detailed investigation of the materials and production techniques used to decorate these buildings has been made. Differences in the mineralogy of the red pigment used on each building indicate a different geological pigment source for each period.     

Environmental impacts around the time of Norse landnám in the Qorlortoq valley,Eastern Settlement,Greenland

Palynology, radiocarbon dating, and open-section stratigraphies from archaeological trenches are used to examine the impact of human activity around the time of Norse landnám on vegetation and landscape associated with a small farm (Ø34) in the Qorlortoq valley, Eastern Settlement, Greenland (61° N 45° W). Peat deposits from a mire abutting the Norse ruins revealed a discontinuous palaeoenvironmental record containing a possible hiatus from ca. AD 410–1020. Palaeovegetational data were recovered either side of this period. Pollen assemblages suggest that open Salix scrub dominated the landscape during the pre-settlement phase. The later phases of landnám resulted in the creation of hay fields and heavily-grazed grassy heath. Site abandonment is reflected by a re-expansion of Salix. This occurs shortly before the onset of deposition of a Sphagnum peat, dated to cal AD 1420–1630 (2σ) and reflecting an increase in mire surface wetness, probably in response to a deteriorating climate. Radiocarbon dates were obtained on peat and plant macrofossils sampled from either side of the proposed hiatus at two different but closely-spaced (<20 m) locations across the mire. These produced significantly different dates for the cessation of peat formation in the pre-landnám period (cal BC 2130–1770 and cal AD 240–410 respectively), but near-synchronous dates for the recommencement of peat growth (cal AD 890–1150 for peat and a probably more reliable interval of cal AD 1020–1190 based on plant macrofossils). It is suggested that this hiatus may represent the first direct evidence for peat cutting in Norse Greenland.     

Radiocarbon Dating of Architectural Mortar: A Case Study in the Maya Region,Quintana Roo,Mexico

Abstract

The use of radiocarbon dating to analyze mortar and charcoal inclusions within mortar or plaster is a useful way to date the construction of architecture, particularly when options for other chronometric methods are limited. In the Yalahau region of northern Quintana Roo, Mexico, members of the Yalahau Regional Human Ecology Project have faced challenges in dating buildings made of large blocks of stone in the Megalithic architectural style. The Megalithic style poses serious problems for any analysis, as excavating into structures with stones weighing several tons can be dangerous, expensive, and time consuming. Additionally, there are no associated sculptures, texts with dates, or other traditionally accessible chronological markers. These factors have resulted in a reliance on a ceramic chronology despite the uncertainty of the dating of many ceramic types in this region, as well as the questionable contextual associations between recovered ceramics and architectural construction phases. Megalithic-style structures at the ancient Maya site of El Naranjal have residual mortar with charcoal inclusions left behind during the mortar-making processes that can be extracted and dated with AMS ¹⁴C methods. Several samples of mortar and charcoal were obtained from structures 1 and 10 from exposed exterior walls and an interior vault. The resulting dates confirm the date for the construction based on ceramics excavated from the same site.     

Palaeolithic radiocarbon chronology: quantifying our confidence beyond two half-lives

It is now three decades since Waterbolk introduced evaluation criteria to ¹⁴C chronology. Despite this, and other subsequent attempts to introduce quality control in the use of ¹⁴C data, no systematic procedure has been adopted by the archaeological community. As a result, our databases may be significantly weakened by questionable dates and/or questionable associations between dated samples and the archaeological phenomena they are intended to represent. As the use of chronometric data in general becomes more ambitious, we must pause and assess how reliable these data are. Here, we forward a set of evaluation criteria which take into account archaeological (e.g. associational, stratigraphic) and chronometric (e.g. pre-treatment and measurement) criteria. We intend to use such criteria to evaluate a large ¹⁴C dataset we have assembled to investigate Late Glacial settlement in Europe, the Near East and North Africa, supported by the Leverhulme Trust. We suggest that the procedure presented here may at least form the basis of the development of more rigorous, scientific use of ¹⁴C dates.     

“The Good,the Bad,and the Ugly”: evaluating the radiocarbon chronology of the middle and late Upper Paleolithic in the Enisei River valley,south-central Siberia

The ¹⁴C record for the Upper Paleolithic in Siberia has remained largely unevaluated and includes good, bad, and ugly dates. Too often researchers accept either all published dates or only those dates that tend to support proposed chronological hypotheses, regardless of sample quality and association. This article systematically evaluates all published ¹⁴C dates (including several newly obtained AMS dates) from middle and late Upper Paleolithic sites in the Enisei River valley of south-central Siberia to establish a reliable chronology for the region and address the tempo of modern human dispersals in Siberia during late Pleistocene times. The revised chronology indicates humans were present before and after the Last Glacial Maximum, but absent during this climatic event. Results also suggest that human population in the region may have increased during the Oldest Dryas.     

Tunnel engineering in the Iron Age: geoarchaeology of the Siloam Tunnel,Jerusalem

The Siloam Tunnel (ST) is the best-identified biblical structure that can be entered today. We use geological, structural, and chemical features of ST and its internal deposits to show that it is an authentic engineering project, without any pre-existing natural conduit that could have guided its excavators. Radiometrically and historically dated to ∼700 BCE, ST pinpoints the technological advance in leveling techniques that was essential for the construction of such a long tunnel without intermediate shafts. A combination of geological and archaeological evidence demonstrates that the circuitous route of ST and the final meeting of the two excavating teams are associated with continuous modifications of the plan to allow acoustic communication between hewers and the surface teams. Hydraulic plaster was applied throughout the tunnel in order to seal voids of dissolution and tectonic origin. Organic material accidentally entrapped in the plaster was carbon 14 dated, and speleothems were dated by U–Th, both corroborating the historic and epigraphic evidence ascribing the engineering advance in tunneling techniques to the Judahite King Hezekiah.     

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.     

Dating the Trollesgave site and the Bromme culture – chronological fix-points for the Lateglacial settlement of Southern Scandinavia

The Bromme culture belongs to the Lateglacial, the period when people settled in the recently deglaciated Southern Scandinavia. Until now there have been only a few imprecise fix-points relating to the chronological position of this archaeological culture. This situation can now be improved with the aid of research results from a Bromme culture settlement at Trollesgave in SE Denmark. Using pollen and plant macrofossil data, Lateglacial lacustrine deposits containing waste material from the settlement can be assigned to the end of the climatically mild Allerød period. A series of ¹⁴C dates establishes the age of the settlement as c. 10 826 ± 49 ¹⁴C years BP (12 871–12 590 cal yr BP). By correlation with climate data from the Greenland ice cores, the occupation can be assigned to the early part of the cold climatic zone GS-1, thus demonstrating that the global ice-core climate zones are not absolutely synchronous with the regional division into biozones.