A Simple(R) Model to Predict the Source of Dietary Carbon in Individual Consumers

Quantitative individual human diet reconstruction using isotopic data and a Bayesian approach typically requires the inclusion of several model parameters, such as individual isotopic data, isotopic and macronutrient composition of food groups, diet‐to‐tissue isotopic offsets and dietary routing. In an archaeological context, sparse data may hamper a widespread application of such models. However, simpler models may be proposed to address specific archaeological questions. As a consequence of the intake of marine foods, individuals from the first century ad Roman site of Herculaneum showed well‐defined bone collagen radiocarbon age offsets from the expected terrestrial value. Taking as reference these radiocarbon offsets and using as model input stable isotope data (δ¹³C and δ¹⁵N), the performance of two Bayesian mixing model instances (routed and concentration‐dependent model versus non‐routed and concentration‐independent) was compared to predict the carbon contribution of marine foods to bone collagen. Predictions generated by both models were in good agreement with observed values. The model with higher complexity showed only a slightly better performance in terms of accuracy and precision. This demonstrates that under similar circumstances, a simple Bayesian approach can be applied to quantify the carbon contribution of marine foods to human bone collagen.     

Carbon accumulation and C/N ratios of peat bogs in North‐West Scotland

Three different Scottish peat bogs were sampled, dated and analysed for carbon (C) and nitrogen (N) concentrations. The mean long‐term apparent rate of C accumulation (LARCA) for the three bogs is 213 g C m^～2 yr^‐1’ over the past eight to nine thousand years, comparable to estimates from other parts of the world with similar climate conditions. Within the catotelm portion of peat sequences, the LARCA is variable, ranging from 4.1 to 72.5 g C m^～2 yr^～1. Rates were highest in the early Holocene, in peat rich in woody fragments, and lowest in the mid‐Holocene during drier periods, followed by increased rates during the late Holocene. Analysis of C/N ratios shows a significant positive correlation with peat humification. This may be because past changes in bog wetness affected the C/N ratios of newly forming peat by altering rates of N mineralisation and loss before incorporation of peat into the catotelm.     

New and past geochemical data on fresh to brine waters of the Salar de Atacama and Andean Altiplano,northern Chile

The paper deals with the major chemistry and stable isotopes (hydrogen, oxygen, carbon, sulfur, strontium) of waters and solutes from the Salar de Atacama basin (Rio Pedro, Honar Creek and Laguna Chaxa) and Andean Altiplano (Laguna Miñique and Laguna Miscanti). The water inflows of the Salar are chemically quite different, the Rio San Pedro being of Na‐Cl type and the Honar Creek of Na‐HCO₃ type, in keeping with the sedimentary‐evaporitic and volcanic nature of the catchment rocks respectively. The δ³⁴S and δ¹⁸O values of sulfate and the ⁸⁷Sr/⁸⁶Sr ratio of strontium in the streams match those of drained rocks, whereas the δ¹³C values of dissolved carbonate are largely controlled by vegetation. The lagoons are evaporated meteoric water bodies, and the relative air humidity estimated from the slope of the isotopic evaporation line is in accordance with historical data on air humidity in the area. The Laguna Chaxa is Na‐Cl rich, and its isotopic composition are consistent with a mixed sedimentary‐volcanic provenance of sulfur and strontium solutes. The Laguna Miñique is Na‐SO₄ rich, and its sulfate δ³⁴S is nearly identical to that of Laguna Chaxa. The δ¹³C(HCO₃) values are quite different in the Laguna Chaxa and Laguna Miñique, with the former being notably enriched in ¹³C probably because of preferential uptake of ¹²C by the high biological productivity occurring in the lagoon. The limited set of new data is interpreted in the context of a much larger literature database. In particular, previous chemical data on inflows and brines in the Salar de Atacama were revisited, and compared with evaporation path models and mineral stability diagrams (boron, lithium and Mg‐minerals) computed using updated software and thermodynamic databases. The modeling shows that the removal of boron and lithium from sulfate‐rich brines possibly occurs, respectively, as ulexite and sulfate salts, and carnallite should be the final magnesium phase of the brine evolution.     

A 6000 Year‐old Fossil Dugong from Botany Bay: Inferences about Changes in Sydney's Climate,Sea Levels and Waterways

The excavation in the 1890s of a skeleton of the warm‐water marine mammal Dugong dugon, associated with Aboriginal artefacts, from a Botany Bay salt marsh, marked the beginning of speculation about climate and sea level change in Australia over the period of human occupation. The dugong bones have recently been dated, giving a conventional ¹⁴C age of 5520±70 years BP, which is consistent with three older ¹⁴C dates for a layer of buried trees that underlies much of the north Botany sediments. The carefully drawn cross‐sections of depositional strata produced by the original discoverers allow further interpretation of the pattern of Holocene sea‐level fluctuations in the Sydney region. Layers of estuarine sediment, such as the one containing the dugong skeleton, are inter‐bedded with peat layers containing in situ roots and stumps, suggesting that the site alternated between sub‐aerial exposure and submergence throughout the Holocene. The presence of the dugong is suggestive of warmer conditions, and its inland location indicates a more extensive Botany Bay in the recent past. This is in agreement with other work from southern New South Wales describing both warm‐water marine species and higher sea levels several thousand years ago.

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Potential Use of Radiometric Data for Wildlife Habitat Modelling

The potential use of existing radiometric data sets, previously collected for prospecting purposes, has very rarely been used as a variable predictor in wildlife habitat modelling. The utility of radiometric data for predicting vegetation community patterns and wildlife habitat was investigated in the Australian arid zone using the Burt Plain bioregion as a case study. Using spatial datasets and a Species Distribution Modelling Toolkit, arid zone vertebrate species were modelled with Generalised Linear Modelling (GLM) regression modelling techniques. These models were used to predict the probability of occurrence of a species at any given location, defined in terms of its environmental attributes. A statistical correlation between the radioactive elements uranium, thorium and potassium, and terrain aspect was found. No statistical correlations were established between the radioactive elements and vegetation patterns; although we suspect these exist at finer scales of mapping. Radiometric data were identified as explanatory variables in the habitat models of all of the 32 vertebrate species examined, and used as illustration in the development of probabilistic spatial predictions of three species (Red Kangaroo, Macropus rufus; Lesser Hairy‐footed Dunnart, Sminthopsis youngsoni; and Rabbit, Oryctolagus cuniculus) in the bioregion. Our analyses suggest that radiometric data sets involving the radioactive elements: (uranium, thorium, and potassium), and vegetation could be used as predictors of biodiversity patterns at the bioregional and landscape level. This is an important finding given the challenges posed in undertaking broad‐scale biological surveys in the arid zone of Australia.     

Developing Direct Displacement-Based Procedures for Simplified Loss Assessment in Performance-Based Earthquake Engineering

Various loss assessment methodologies have been proposed and developed over the past decades to provide risk assessment on a regional scale. There is an increasing need, however, to provide engineers with practical tools for building-specific loss assessment. Recently, progress has been made towards probabilistic loss models such as the PEER framework. However, as comprehensive probabilistic methodologies could be too complex for practicing engineers, this article presents a simplified probabilistic loss assessment methodology that builds on a direct displacement-based framework. The methodology is tested via examination of two RC frame buildings and encouragingly shows similar results to the PEER methodology.     

MEASURING CHRONOLOGICAL UNCERTAINTY IN INTENSIVE SURVEY FINDS: A CASE STUDY FROM ANTIKYTHERA,GREECE*

This paper considers how to make the most out of the rather imprecise chronological knowledge that we often have about the past. We focus here on the relative dating of artefacts during archaeological fieldwork, with particular emphasis on new ways to express and analyse chronological uncertainty. A probabilistic method for assigning artefacts to particular chronological periods is advocated and implemented for a large pottery data set from an intensive survey of the Greek island of Antikythera. We also highlight several statistical methods for exploring how uncertainty is shared amongst different periods in this data set and how these observed associations can prompt more sensitive interpretations of landscape‐scale patterns. The concluding discussion re‐emphasizes why these issues are relevant to wider methodological debates in archaeological field practice.     

Zoos as heritage tourism attractions: A neglected area of research?

Abstract

Zoos are a form of museum.¹ The main difference between zoos and other forms of museum is that zoos exhibit living objects. These objects are examples of natural heritage. Unlike other museums, the focus of much research in the past decade, zoos appear under‐researched. Zoos, however, are significant tourist attractions. There are over 10,000 zoos worldwide,² many in major world cities and some attract millions of visitors annually. Zoos date back at least three thousand years, but their role has been changing in the past twenty‐five years from menageries to conservation centres. Concern recently has focused on animal welfare when wildlife is in captivity, and this has led to a re‐examination of the purpose of zoos. This article examines the aims of zoos, their nature as heritage‐tourism attractions and the profile of zoo visitors. In an attempt to establish a new research agenda, the article also examines issues about the future of zoos, including questions concerning potential and real conflict between their educational, scientific and entertainment roles.     

Some Remarks About the Future of Geographical Analysis: The Journal and the Sub‐Discipline

This paper expands upon a GA 50^th Anniversary panel presentation made at the 2018 New Orleans American Association of Geographers meeting. It notes that retrospectives for this topic already exist, both in terms of the journal and the sub‐discipline. This paper presents discussion about the following selected prominent transitional themes bridging the past and the future of geographical analysis: space–time data; geographic uncertainty and error; and, dimensional reduction spatial statistical modeling. It also presents discussion about the following three themes that are expected to receive considerable future attention: negative spatial autocorrelation; synergies between spatial statistics and spatial optimization; and, big spatial data. The first two of these topics essentially have been ignored in the literature to date.     

THE ARCHAEOINTENSITY OF THE EARTH'S MAGNETIC FIELD RETRIEVED FROM PAMPEAN CERAMICS (SOUTH AMERICA)

Absolute intensity determinations using the Coe variant of the Thellier method have been carried out on some selected pottery fragments collected in the wetlands of the lower Paraná (Pampean region, Argentina) in order to construct the first archaeointensity master curve for South America. Associated radiometric ages range between 1640 ± 70 and 730 ± 70 bp . Twenty‐one samples (five fragments) out of 46 studied (eight fragments) provided successful absolute intensity determinations. The fragment‐mean archaeointensity values obtained in this study range from 21.9 ± 2.3 to 42.6 ± 5.4 μT, with corresponding virtual axial dipole moments (VADMs) ranging from 4.0 ± 0.5 to 8.1 ± 1.0 x 10²²Am². This corresponds to a mean VADM of (6.4 ± 1.8) × 10²² Am². The synthetic record retrieved from southern Argentina and Brazil consists of 17 mean archaeointensities distributed between approximately ad 700 and ad 1700. The data set shows several distinct periods of fluctuations of quite large intensity. However, most data are concentrated into a relatively narrow time period from ad 950 to ad 1300. Three general features may be detected: the time intervals from about ad 950 to 1130 and 1350 to 1480 are characterized by quite monotonic increases of geomagnetic intensity, while some decrease is observed from ad 1150 to 1280. These variations may be speculatively correlated to climate changes over multi‐decadal time scales. Important differences are observed between the data and the geomagnetic field predictions derived from recently reported global models, which reinforces the importance of regional reference curves for dating purposes.     

Salt tectonics and shallow subseafloor fluid convection: models of coupled fluid‐heat‐salt transport

Thermohaline convection associated with salt domes has the potential to drive significant fluid flow and mass and heat transport in continental margins, but previous studies of fluid flow associated with salt structures have focused on continental settings or deep flow systems of importance to petroleum exploration. Motivated by recent geophysical and geochemical observations that suggest a convective pattern to near‐seafloor pore fluid flow in the northern Gulf of Mexico (GoMex), we devise numerical models that fully couple thermal and chemical processes to quantify the effects of salt geometry and seafloor relief on fluid flow beneath the seafloor. Steady‐state models that ignore halite dissolution demonstrate that seafloor relief plays an important role in the evolution of shallow geothermal convection cells and that salt at depth can contribute a thermal component to this convection. The inclusion of faults causes significant, but highly localized, increases in flow rates at seafloor discharge zones. Transient models that include halite dissolution show the evolution of flow during brine formation from early salt‐driven convection to later geothermal convection, characteristics of which are controlled by the interplay of seafloor relief and salt geometry. Predicted flow rates are on the order of a few millimeters per year or less for homogeneous sediments with a permeability of 10^?15 m², comparable to compaction‐driven flow rates. Sediment permeabilities likely fall below 10^?15 m² at depth in the GoMex basin, but such thermohaline convection can drive pervasive mass transport across the seafloor, affecting sediment diagenesis in shallow sediments. In more permeable settings, such flow could affect methane hydrate stability, seafloor chemosynthetic communities, and the longevity of fluid seeps.     

Pore pressure evolution and fluid flow during visco‐elastic single‐layer buckle folding

Pore pressure and fluid flow during the deformational history of geologic structures are directly influenced by tectonic deformation events. In this contribution, 2D plane strain finite element analysis is used to study the influence of different permeability distributions on the pore pressure field and associated flow regimes during the evolution of visco‐elastic single‐layer buckle folds. The buckling‐induced fluid flow regimes indicate that flow directions and, to a lesser degree, their magnitudes vary significantly throughout the deformation and as a function of the stratigraphic permeability distribution. The modelling results suggest that the volumetric strain and the permeability distribution significantly affect the resulting flow regime at different stages of fold development. For homogeneous permeability models (k > 10^?21 m²), low strain results in a mostly pervasive fluid flow regime and is in agreement with previous studies. For larger strain conditions, fluid focusing occurs in the buckling layer towards the top of the fold hinge. For low permeabilities (<10^?21 m²), local focused flow regimes inside the buckling layer emerge throughout the deformation history. For models featuring a low‐permeability layer embedded in a high‐permeability matrix or sandwiched between high‐permeability layers, focused flow regimes inside the folded layer result throughout the deformation history, but with significant differences in the flow vectors of the surrounding layers. Fluid flow vectors induced by the fold can result in different, even reversed, directions depending on the amount of strain. In summary, fluid flow regimes during single‐layer buckling can change from pervasive to focused and fluid flow vectors can be opposite at different strain levels, that is the flow vectors change significantly through time. Thus, a complete understanding of fluid flow regimes associated with single‐layer buckle folds requires consideration of the complete deformation history of the fold.     

KLAVS RANDSBORG AND THE NINTH CENTURY AD

Archaeology over the past fifty years has shown that in the early 9^th century Western Europe experimented with a coalescing of states affirmed by a common reform ideology and with it increased communication to regions beyond. At different speeds, regions of Western Europe adopted this new strategy known as the correctio. Within a generation, the correctio gave rise to a new ‘feudal’ economy and significantly a new regionalism. The archaeology of Europe shows that there were winners and losers in these fast‐changing regions. The losers, in many cases, controlled the written narratives and ascribed their altered socio‐economic condition to the Others of the time, not least because the Others were leading exponents of the post‐correctio economic agenda. This paper revisits Klavs Randsborg's groundbreaking book, The Viking Age of Denmark, in the context of post‐war approaches to Europe's post‐classical narrative.     

Patterns of plant δN values on a Greenland Norse farm

In a further empirical study of the impact of past human activities on modern plant δ¹⁵N values, plants were collected in each of two growing seasons from several defined contexts of an inland Norse farm in southwest Greenland. The δ¹⁵N measures of the plants show a clear distinction between areas with definite evidence of past human activity and those without. The data for the plants on this farm's infield indicates that it was purposely fertilized. The intriguing intra- and inter-variations in the ¹⁵N values of plants from several structures are not easily explained, but the differences appear to reflect the different functions of the various farm structures. The findings of this study suggest practical applications for future use of plant δ¹⁵N values in archaeology.     

New Statistical Approaches to Intra‐individual Isotopic Analysis and Modelling of Birth Seasonality in Studies of Herd Animals

This paper introduces improved methods for statistically assessing birth seasonality and intra‐annual variation in δ¹⁸O from faunal tooth enamel. The first method estimates input parameters for use with a previously developed parametric approach by C. Tornero et al. The second method uses a non‐parametric clustering procedure to group individuals with similar time‐series data and estimate birth seasonality. This method was successful in analysing data from a modern sample with known season of birth, as well as two heterogeneous archaeological data sets. Modelling indicates that the non‐parametric approach estimates birth seasonality more successfully than the parametric method when less of the tooth row is preserved. The new approach offers a high level of statistical rigour and flexibility in dealing with the time‐series data produced through intra‐individual sampling in isotopic analysis.     

Hydrothermal monitoring in a quiescent volcanic arc: Cascade Range,northwestern United States

Ongoing (1996–present) volcanic unrest near South Sister, Oregon, is accompanied by a striking set of hydrothermal anomalies, including elevated temperatures, elevated major ion concentrations, and ³He/⁴He ratios as large as 8.6 R_A in slightly thermal springs. These observations prompted the US Geological Survey to begin a systematic hydrothermal‐monitoring effort encompassing 25 sites and 10 of the highest‐risk volcanoes in the Cascade volcanic arc, from Mount Baker near the Canadian border to Lassen Peak in northern California. A concerted effort was made to develop hourly, multiyear records of temperature and/or hydrothermal solute flux, suitable for retrospective comparison with other continuous geophysical monitoring data. Targets included summit fumarole groups and springs/streams that show clear evidence of magmatic influence in the form of high ³He/⁴He ratios and/or anomalous fluxes of magmatic CO₂ or heat. As of 2009–2012, summit fumarole temperatures in the Cascade Range were generally near or below the local pure water boiling point; the maximum observed superheat was <2.5°C at Mount Baker. Variability in ground temperature records from the summit fumarole sites is temperature‐dependent, with the hottest sites tending to show less variability. Seasonal variability in the hydrothermal solute flux from magmatically influenced springs varied from essentially undetectable to a factor of 5–10. This range of observed behavior owes mainly to the local climate regime, with strongly snowmelt‐influenced springs and streams exhibiting more variability. As of the end of the 2012 field season, there had been 87 occurrences of local seismic energy densities approximately ≥ 0.001 J/m³ during periods of hourly record. Hydrothermal responses to these small seismic stimuli were generally undetectable or ambiguous. Evaluation of multiyear to multidecadal trends indicates that whereas the hydrothermal system at Mount St. Helens is still fast‐evolving in response to the 1980–present eruptive cycle, there is no clear evidence of ongoing long‐term trends in hydrothermal activity at other Cascade Range volcanoes that have been active or restless during the past century (Baker, South Sister, and Lassen). Experience gained during the Cascade Range hydrothermal‐monitoring experiment informs ongoing efforts to capture entire unrest cycles at more active but generally less accessible volcanoes such as those in the Aleutian arc.     

INVESTIGATING SEASONALITY AND SEASON OF BIRTH IN PAST HERDS: A REFERENCE SET OF SHEEP ENAMEL STABLE OXYGEN ISOTOPE RATIOS

Intra‐tooth sequential analysis of enamel δ¹⁸O is currently used to investigate birth seasonality in past animal populations, offering new insights into seasonal availability of animal resources, herd management and seasonality of site occupation. Reference data sets are still required to address two major difficulties: (1) that inter‐individual variability in the record of the seasonal cycle is affected by tooth size; and (2) that the season of birth cannot be directly estimated from the timing of tooth growth, because of a delay in enamel mineralization. We present a data set acquired on the lower second molar of 10 modern sheep from Rousay (Orkney) born within a few weeks of each other in April/May and submitted to the same environmental conditions until death. All sheep have recorded a sinusoidal pattern of δ¹⁸O variation spanning approximately a year. From the difference between the expected and the measured time sequence, the delay of enamel mineralization is estimated to be 5–6 months. The data set is then described using a model mainly based on a cosine function. The period, corresponding to the length of the M2 crown formed over a year, averaged 35.8 mm. A very slight variation of tooth growth rate with time and no attenuation of the isotopic signal towards the cervical margin of the crown could be detected in this data set. The lowest δ¹⁸O values, corresponding to the sheep's first winter, were tracked at a distance from the enamel/root junction that varied between 23.0 and 30.3 mm (x_min mean = 27.6 mm); the highest δ¹⁸O values, corresponding to the sheep's second summer, were between 6.3 and 11.6 mm (x_max mean = 9.9 mm). Most of the variability can be attributed to tooth size. When normalized on the period, x_min and x_max are 0.28 (± 0.05) and 0.78 (± 0.05) on average, meaning that the Rousay sheep have recorded the minimum and maximum δ¹⁸O values on average at 78% and 28%, respectively, of the end of the periodic cycle recorded in the second molar.     

Mathematical modeling of phase separation of seawater near an igneous dike

We provide a simplified treatment of phase separation of seawater near an igneous dike to obtain rough estimates of the thickness and duration of the two‐phase zone, the volume fractions of vapor and brine formed, and their distribution in the subsurface. Under the assumption that heat transfer occurs mainly by thermal conduction we show that, for a 2‐m wide dike, the maximum width of the two phase zone is approximately 20 cm and that a zone of halite is initially deposited near the dike wall. The two‐phase zone is mainly filled with vapor. For a value of thermal diffusivity of a = 10^?6 m² sec^?1, the two‐phase zone begins to disappear at the base of the system after 13 days, and disappears completely by 16 days. For a lower value of thermal diffusivity, the width of the two‐phase region does not change appreciably but its duration increases as a^?1. The width of the two‐phase zone determined by this simplified model agrees reasonably well with transient numerical solutions for the analogous two‐phase flow in a pure water system; however the duration of two‐phase flow is matched better using a smaller value of a. We compare the seafloor values of vapor salinity and temperature given by the model with vapor salinity data from the ‘A’ vent at 9–10°N on the East Pacific Rise (EPR) and argue that either non‐equilibrium thermodynamic behavior or near‐surface mixing of brine with vapor in the two‐phase region may explain the discrepancies between model predictions and data.     

Unmanaging the past: Truth,data and the human being

Management systems in archaeology seek to impose the scientific objective‐reductionist paradigm on archaeologists and their data. This orthodoxy has been enshrined in English Heritage's document Management of Archaeological Projects (English Heritage 1991) which prescribes rigorous application of a standardized methodology. MAP II, as it is known, is based on a processual model in which ‘data’ enter at one end and valuable archaeology emerges at the other. Such a view not only lacks any appreciation of the distinctions between ‘data’ and ‘information’ but also fails to acknowledge the beliefs and values which underpin the decision‐making criteria crucial to the model. In this paper we argue for an approach which un‐manages the past — by building relativistic humans into our strategies for dealing with the past. Examples are given which demonstrate how such an approach might work in practice.     

ART‐P‐MAP Neural Networks Modeling of Land‐Use Change: Accounting for Spatial Heterogeneity and Uncertainty

Spatial land‐use models over large geographic areas and at fine spatial resolutions face the challenges of spatial heterogeneity, model predictability, data quality, and of the ensuing uncertainty. We propose an improved neural network model, ART‐Probability‐Map (ART‐P‐MAP), tailored to address these issues in the context of spatial modeling of land‐use change. First, it adaptively forms its own network structure to account for spatial heterogeneity. Second, it explicitly infers posterior probabilities of land conversion that facilitates the quantification of prediction uncertainty. Extensive calibration under various test settings is conducted on the proposed model to optimize its utility in seeking useful information within a spatially heterogeneous environment. The calibration strategy involves building a bagging ensemble for training and stratified sampling with varying category proportions for experimentation. Through a temporal validation approach, we examine models’ performance within a systematic assessment framework consisting of global metrics and cell‐level uncertainty measurement. Compared with two baselines, ART‐P‐MAP achieves consistently good and stable performance across experiments and exhibits superior capability to handle the spatial heterogeneity and uncertainty involved in the land‐use change problem. Finally, we conclude that, as a general probabilistic regression model, ART‐P‐MAP is applicable to a broad range of land‐use change modeling approaches, which deserves future research.