Sequential, Bayesian Geostatistics: A Principled Method for Large Data Sets

The principled statistical application of Gaussian random field models used in geostatistics has historically been limited to data sets of a small size. This limitation is imposed by the requirement to store and invert the covariance matrix of all the samples to obtain a predictive distribution at unsampled locations, or to use likelihood-based covariance estimation. Various ad hoc approaches to solve this problem have been adopted, such as selecting a neighborhood region and/or a small number of observations to use in the kriging process, but these have no sound theoretical basis and it is unclear what information is being lost. In this article, we present a Bayesian method for estimating the posterior mean and covariance structures of a Gaussian random field using a sequential estimation algorithm. By imposing sparsity in a well-defined framework, the algorithm retains a subset of " basis vectors " that best represent the " true " posterior Gaussian random field model in the relative entropy sense. This allows a principled treatment of Gaussian random field models on very large data sets. The method is particularly appropriate when the Gaussian random field model is regarded as a latent variable model, which may be nonlinearly related to the observations. We show the application of the sequential, sparse Bayesian estimation in Gaussian random field models and discuss its merits and drawbacks.     

Discriminant function analyses in archaeology: are classification rates too good to be true?

The use of discriminant function analyses (DFA) in archaeological and related research is on the increase, however many of the assumptions of this method receive a mixed treatment in the literature. Statisticians frequently use complex statistical models to investigate analytical parameters, but such idealised datasets may be hard to relate to “real-life” examples and the literature difficult to assess. Using two faunal datasets that are more typical of archaeological and related research, one comprised of size-corrected linear measurements of bovid humeri and another of 3D geometric morphometric (GMM) shape data of African monkey skulls, and two simulated datasets, we illustrate some of the most important but often ignored issues of DFA. We specifically show why it is paramount to address “over-fitting” by cross-validation when applying this method and how the probability of correctly classifying cases by chance can be properly and explicitly taken into account.     

The Effect on Attribute Prediction of Location Uncertainty in Spatial Data

A datum is considered spatial if it contains location information. Typically, there is also attribute information, whose distribution depends on its location. Thus, error in location information can lead to error in attribute information, which is reflected ultimately in the inference drawn from the data. We propose a statistical model for incorporating location error into spatial data analysis. We investigate the effect of location error on the spatial lag, the covariance function, and optimal spatial linear prediction (that is, kriging). We show that the form of kriging after adjusting for location error is the same as that of kriging without adjusting for location error. However, location error changes entries in the matrix of explanatory variables, the matrix of co‐variances between the sample sites, and the vector of covariances between the sample sites and the prediction location. We investigate, through simulation, the effect that varying trend, measurement error, location error, range of spatial dependence, sample size, and prediction location have on kriging after and without adjusting for location error. When the location error is large, kriging after adjusting for location error performs markedly better than kriging without adjusting for location error, in terms of both the prediction bias and the mean squared prediction error.     

A New Method For Combining Lead Isotope and Lead Abundance Data to Characterize Archaeological Copper Alloys*

We present a new methodology for interpreting lead isotope data from archaeological copper alloy objects. It is not based on the conventional isotope ratio biplots, which were originally devised to allow the calculation of the geological age of the lead mineralization, but is derived from isotope mixing models, more often used for presenting strontium isotope data. We illustrate the method by reworking published data on Sardinian Nuragic oxhide ingots and copper alloy artefacts. While we confirm the consensus assumption that the oxhide ingot fragments found on Sardinia are isotopically consistent with Cypriot copper ores (although we see no isotopic reason to favour only Apliki, as originally suggested), we also show that there is evidence for mixing between local and ingot copper in some objects, which was previously not detected. More broadly, we suspect that the apparent mismatch between some source allocations for copper drawn from isotope geochemistry and the rest of the archaeological data in some cases might be due to mixed isotopic signals being incorrectly assigned to a specific source, and suggest that the method presented here will reduce the chances of this happening.     

Trace element and Pb isotope provenance analyses of native copper in northwestern North America: results of a recent pilot study using INAA,ICP-MS,and LA-MC-ICP-MS

Several indigenous groups in northwestern North America used native copper prior to EuroAmerican contact. The Arctic, Subarctic, and Northwest Coast culture areas all have archaeological finds and geological sources of native copper. The copper-rich region of south-central Alaska and southwestern Yukon has often been credited as the source of archaeological native copper found on the Northwest Coast despite the presence of native copper sources further south. This paper presents the results of a pilot study using INAA, ICP-MS, and LA-MC-ICP-MS to assess the potential for native copper provenance research in Alaska and the Yukon Territory. Discrete native copper sources could be distinguished from one another intra-regionally. Difficulties associated with future native copper provenance research in northwestern North America are discussed.     

Reconstruction of local environments of ancient population in a changeable river valley landscape (The Middle Vychegda River,Northern Russia)

In river valleys, both human occupation and subsequent preservation of archaeological sites are affected by active landscape transformation caused by river lateral migration, incision/aggradation cycles and changes of river hydrological regime. In the middle Vychegda River valley (Northern Russia), there are numerous traces of human presence since the Mesolithic. We exploit multi-disciplinary archaeological, geomorphological and geochronological approach to elucidate the environmental preferences of settlements positioning during different epochs of the Holocene. High resolution space image supplemented with data on alluvial stratigraphy derived from bank exposures and hand cores, as well as 51 radiocarbon dates were used to make the geomorphic map showing ages of floodplain/terrace segments and palaeochannels. Using this map together with sediment facial interpretation, position of archaeological sites was analysed in the context of local geomorphic and hydrologic situation. The majority of archaeological sites and modern settlements are found on terraces at river banks or at oxbow lakes which were well connected to the river. Few exceptions from this rule may be explained by seasonal character of dwelling functioning, ritual burial practice or specialization of settlements. Geomorphic situation was used as a background for planning further prospection of different-age archaeological objects.     

Authenticity,antiquity and archaeology

If nationalism shaped the assumptions and methods of archaeology for well over a century, archaeological concepts and practices made a significant contribution to the nationalist ideal of the distinctive, territorial nation. This is partly because nationalism and archaeology shared a belief in the ethnic uniqueness and tangibility of archaeological cultures, and partly because of the influence of key archaeological concepts and practices. The latter included a profound concern with the authenticity of material cultures; the related belief in ethnic rootedness in the historic territory; archaeology's well‐known interest in the antiquity of civilisations; and its use of the stratigraphic method to analyse continuity and change. Aside from these contributions, the archaeological domain provides a repertoire of vivid symbolism in its often spectacular ‘finds’, which have been able to express and embody the nation's unique culture and the intimate nature of the national bond.     

A human-centered GIS approach to modeling mobility on southern Baffin Island,Nunavut, Canada

Southern Baffin Island has been occupied for several millennia, but its enormous size, coupled with scarcity of identified inland archaeological sites that can be confidently linked to coastal occupations, makes modeling ancient seasonal mobility across the region through traditional cost-surface least-cost pathway approaches impractical. We present a method that combines weighted multi-criteria cost surface analysis with a watershed function to create a “mobility-shed” of non-winter travel pathways covering the study area. We evaluate the predictive utility of the resulting pathways for future archaeological survey by assessing their spatial relationships to known archaeological sites. The results of this comparison suggest that elevation and land cover criteria should be augmented with ethnographic and resource availability data to model mobility in this region.     

CROSS‐CHANNEL CONNECTIVITY: WEALDEN WHETSTONE IMPORTS FROM ROMAN BRITAIN TO THE CONTINENT

The purpose of this paper is to demonstrate cross‐Channel exchange of calcareous sandstone‐type whetstones derived from the Weald (Sussex, UK) in the Roman period. The presence of this particular type of whetstone at several Roman sites on the Continent – more specifically, in Belgium, France and the Netherlands – is reported for the first time. The morphology, geological provenance, petrographic characteristics and distribution patterns are discussed, based on a comparative analysis with archaeological and geological reference material. The geological analysis identifies a common geological source for the Continental finds: the very fine‐grained, thin‐bedded, flagstone‐like calcareous sandstone beds of the Lower Cretaceous Wealden Clay Formation. These sandstones were, most probably, extracted in the north‐western part of the Weald area. The distribution pattern of the archaeological material implies the importance of personal mobility, with potential military affinities.     

Excavating Under Gunfire: Archaeologists in the Aegean During the First World War

Abstract

The Gallipoli campaign in 1915 revealed remains of the cemeteries of the Greek settlement of Elaious. French troops from the Corps expéditionnaire d'Orient were assigned to investigate the site, often under Turkish gunfire. This work was supervised by former students of the École française d'Athènes. Detailed plans were made, the finds catalogued, and a published report issued. During the subsequent campaign in Macedonia, the French team made a detailed study of the archaeological remains and objects discovered in the French sector. Ernest Gardner, the former director of the British School at Athens, had been posted to Salonica as a member of the Eastern Mediterranean Special Intelligence Bureau (EMSIB). He studied the finds from the British sector and created a museum for the finds in Salonica. Some other archaeological work continued in Greece during the war years, though not close to the front. Such dedicated archaeological work in a battlefield situation was the precursor to more specialized units that developed during the Second World War.     

Using event-history analysis to examine the causes of semi-sedentism among shifting cultivators: a case study of the Haudenosaunee,AD 1500–1700

Event-history analysis is often used in the social sciences to study the occurrence of particular events over the lifespan of individuals and the impact of various factors on the rate at which those events occur. Like individuals, settlements can be analyzed and important events, such as founding or abandonment, can be studied using this method. Thus, as Richard Paine (1992) has noted, the technique can be useful in archaeological investigations of settlement processes. In this research we use it to explore the causes of settlement abandonment among a temperate shifting cultivators in an attempt to better understand the ecology of this adaptation and in order to evaluate the merits of the method. The sixteenth- and seventeenth-century Haudenosaunee (Iroquois) of northeastern North America present an interesting case study for applying event-history analysis to archaeological settlement dynamics because of the wealth of archaeological settlement data and detailed historic record that allows us to parse out historical factors and analyze the remaining ecological factors. We use event-history analysis as an alternative means for evaluating the relative and absolute effects of several variables that may have been predictive of the lifespan of settlements and the timing of their removal. The results suggest that the decision to move from a village was a complex process in which the population size of a village may have been the single most important, but not the only, determinant of settlement duration.     

Geostatistical Smoothing of Areal Data: Mapping Employment Density with Factorial Kriging

This article summarizes area-to-point (ATP) factorial kriging that allows the smoothing of aggregate, areal data into a continuous spatial surface. Unlike some other smoothing methods, ATP factorial kriging does not suppose that all of the data within an area are located at a centroid or other arbitrary point. Also, unlike some other smoothing methods, factorial kriging allows the user to utilize an autocovariance function to control the smoothness of the output. This is beneficial because the covariance function is a physically meaningful statement of spatial relationship, which is not the case when other spatial kernel functions are used for smoothing. Given a known covariance function, factorial kriging gives the smooth surface that is best in terms of minimizing the expected mean squared prediction error. I present an application of the factorial kriging methodology for visualizing the structure of employment density in the Denver metropolitan area.     

ELECTROCHEMISTRY AND AUTHENTICATION OF ARCHAEOLOGICAL LEAD USING VOLTAMMETRY OF MICROPARTICLES: APPLICATION TO THE TOSSAL DE SANT MIQUEL IBERIAN PLATE

An essentially non‐invasive electrochemical methodology addressed to the authentication of archaeological lead is described. The method is based on the record of the voltammetric response of nanosamples from the archaeological artefact mechanically transferred to a graphite ‘pencil’ electrode in contact with aqueous buffers. Three diagnostic criteria for authentication are described based on the appearance of: (i) oxidative dissolution signals for trace metals like copper, arsenic, antimony and, often, tin and silver accompanying stripping peaks for lead, (ii) peak potential shifts for reduction peaks for patination products, and (iii) the presence of reduction peaks for PbO₂. The method is applied to the authentication of an Iberian lead plate from the Tossal de Sant Miquel (Llíria, Spain) site using a series of genuine and false pieces from different provenances in the Valencian region (Spain).     

Hesitant hunters: a review of the introduction of agriculture in western Norway

Abstract

Evidence for the introduction of agriculture in western Norway is presented, using three categories of data: (1) palaeobotanical data, including pollen diagrams from lakes, bogs and archaeological sites, focusing on the presence of cereals, Plantago lanceolata L. and anthropogenic pollen indicators, and charred macro remains of cereals from archaeological sites; (2) osteological data, focusing on the occurrences of bones of cattle, sheep and goats in three rock-shelters, and the bone material from one open-air Neolithic site; (3) archaeological data, including artefacts indicating agricultural practices, distribution of residential settlement sites, and stray finds. The evidence for agricultural activity at the beginning of the fourth millennium BC (Early Neolithic, EN) is low, whereas the presence of both cereals and animal husbandry is indicated in the palaeobotanical material from the Middle Neolithic A (MNA, 3400–2600 cal. BC). The earliest record of domesticated animal bones is dated to the Middle Neolithic B (MNB, 2600–2200 cal. BC), while palynological and archaeological data also indicate an expansion in the area cultivated by early farmers. All data confirm the establishment of an agrarian society and animal husbandry in the Late Neolithic (LN, 2200–1700 cal. BC). It is concluded that agriculture was introduced into western Norway by the indigenous hunter-fisher populations. During this process, social and ideological factors played principal roles.     

A Tale of Two Yusifs: Recovering Arab Agency in Palestine Exploration Fund Excavations 1890–1924

The scholarly literature on the history of archaeology and archaeological organisations in late nineteenth/early twentieth century Palestine focuses almost exclusively on the Western excavators and scholars who headed this work. But Arab workers did the bulk of the actual digging, and on a daily basis they were often overseen by fellow Arabs as foremen and gang leaders. This paper applies lessons from relational history as it has been used in Levantine intellectual and labour contexts to understand the roles of two particular men, Yusif ‘abu Selim' Khazin and Yusif Khattar Kanaan, who worked for the Palestine Exploration Fund between 1890 and World War One, acting as foremen, researchers, site directors and many other roles for Frederick Bliss, R.A.S Macalister, and Duncan Mackenzie. Despite their often slim and ghostly presence in the records, in which both men are often referred to only by their shared first name, the writings of Bliss and Macalister reveal them to have been indispensable on-site and as offering insights and knowledge which influenced how both archaeological finds and indigenous life in Palestine was understood.     

Spatial autocorrelation tests and the Classic Maya collapse: Methods and inferences

Spatial autocorrelation, resulting in pattern or structure in geographically distributed data, is discussed in theoretical and practical terms. Tests for spatial autocorrelation are presented, along with an explication of the relationship between autocorrelation models, the product-moment correlation coefficient and the spatial autocorrelation test statistic. Two archaeological examples illustrate the application of the auto-correlation test statistic. The first uses a hypothetical data set, which shows the type of map patterns that appear with various levels of spatial autocorrelation, and the second examines the terminal distribution of long-count-dated monuments at lowland Classic Maya sites. The results of the second example fail to support arguments for simple patterning in the cessation of the erection of these monuments and, by inference, in the Maya collapse itself. Finally, it is argued that while the identification of spatial autocorrelation is often the goal of spatial analyses, the presence of autocorrelation violates the assumptions of certain statistics used in such analyses.     

A Bayesian Updating Applied to Earthquake Ground-Motion Prediction Equations for Iran

This article presents new ground-motion prediction equations for three distinct seismic regions of Iran via updating the previous global model using observed data for each region by means of Bayesian updating. The Bayesian theory has the advantage that it results in more accurate results even in situations when little data is available. This leads the way for updating global models to obtain new local models for seismotectonic regions with little available data like Iran. The proposed updated model was compared against currently available models for Iran and the results reveal the overall stability and quality performance of the proposed model.     

The application of LiDAR-based DEMs on WWII conflict sites in the Netherlands

Airborne Laser Scanning or Light Detecting And Ranging (LiDAR) is quite a new technique for most archaeologists. Digital Elevation Models (DEMs), derived from the LiDAR-data, can be very useful to map archaeological sites in order to get a better overview of what is left and how these remains should be protected and researched further. LiDAR-based DEMs can be extremely useful to conflict archaeologists, especially in the Netherlands where excavation of the remains of World War II (WWII) is often problematic. Using DEMs it is possible to make both an indication of the archaeological and the heritage value of a conflict site. The use of DEMs will improve the prospection, mapping and monitoring of archaeological sites.     

The ESR geochronology and geology of the open‐air Palaeolithic deposits in Bollschweil,Germany*

This paper presents ESR (electron spin resonance) ages of rhinoceros and equine tooth enamel from the open‐air Palaeolithic site of Bollschweil on the western edge of the Black Forest near Freiburg, Germany. Bollschweil is one of very few archaeological sites in southern Germany to yield Lower or Middle Palaeolithic faunal and lithic materials from a buried, open‐air context. The geological context of the archaeological remains indicates that the loessic sediments have been reworked. Excavation at this site yielded a cold‐period fauna characterized by bones of mammoth, horse, large bovids and wooly rhinoceros. In the absence of any clear chronostratigraphic marker horizons, the age of the finds could not be determined without the use of a chronometric dating method. Lithic artefacts from the site, including a handaxe and a side scraper, suggest either a Middle Pleistocene or early Late Pleistocene age. The ESR dating results indicate that the deposit enclosing the archaeological finds should be assigned to oxygen isotope stage (OIS) 6, although there exists some possibility that some teeth were deposited later, in OIS 5.     

THE BAYESIAN APPROACH TO THE INTERPRETATION OF ARCHAEOLOGICAL DATA

Archaeologists are increasingly becoming aware of an approach to data investigation known as Bayesian statistics. In this paper we outline both the philosophical and statistical background to the approach. We show that it provides a logical and coherent framework in which to make inferences on the basis of both data and a priori expert knowledge. We note that adoption of the Bayesian framework is particularly timely since there have been recent dramatic developments in numerical methods which mean that a number of previous implementation problems have now been solved. As a result, many questions of archaeological interest, which require the use of complex statistical models, are being investigated using this methodology. We use a variety of recently published examples from a range of archaeological areas to illustrate the type of questions that can be answered and the nature of the methodologies used, and we make comparisons with the results obtained using more traditional statistical techniques.