The impact of manuring on nitrogen isotope ratios in cereals: archaeological implications for reconstruction of diet and crop management practices

Recent archaeological studies of human diet have used stable nitrogen isotope ratios (δ¹⁵N) from human bone collagen to infer the relative importance of terrestrial plant and animal foods. This approach is based on widely observed enrichment of δ¹⁵N up the food chain, plants having distinctly lower values than the herbivores that consume them. Studies of early farming diets in Britain, Denmark and Germany have tended to detect relatively high δ¹⁵N values (e.g. c. +9‰), interpreted as evidence of a diet largely based on animal products, though archaeobotanical evidence for crop cultivation (e.g. carbonised cereal grain and chaff) is widespread. This paper investigates the impact of manuring on δ¹⁵N values in modern cereals, and of charring on these cereal values. The results from two long-term experiments demonstrate that manuring significantly raises δ¹⁵N in cereal grain and chaff. Depending on manuring levels and frequency, it appears that human diets with a major component of such grain would conventionally be interpreted as indicating a largely animal-based diet or a mixed plant/animal diet. Moreover, preliminary analyses of experimentally charred grain and chaff from manured and unmanured conditions are promising for the extraction of reliable ancient δ¹⁵N values from archaeobotanical cereal remains. The wider implications of these results, and the need for further work, are discussed.     

Rice chaff in ceramics from the archaeological site of Sumhuram (Dhofar,Southern Oman)

The identification of the chaff used as temper in ancient ceramics represents a possible source of information about the area of origin of the pottery. This paper studies the occurrence of rice (Oryza sp.) chaff in potsherds from the archaeological site of Sumhuram (Dhofar, Sultanate of Oman). The information gathered at the site offers insight into commerce routes and networks to which the town belonged in the first centuries AD. The analysis of the plant material in the pottery and potsherds can also furnish interesting data on the ancient technologies of pottery production.     

4500-Year old domesticated pearl millet (Pennisetum glaucum) from the Tilemsi Valley,Mali: new insights into an alternative cereal domestication pathway

We report here new evidence from the Lower Tilemsi Valley in northeastern Mali, which constitutes the earliest archaeobotanical evidence for domesticated pearl millet (Pennisetum glaucum), predating other finds from Africa or India by several centuries. These materials provide further morphological details on the earliest cultivated pearl millet. Our results demonstrate that pearl millet non-shattering evolved earlier than the start of grain size increases and that once domesticated, pearl millet spread widely and rapidly. Additional attention is given to the dating of these materials, highlighting potential flaws in the use of organic chaff tempered pottery to date occurrences of pearl millet. A revised chronology, based on detailed Bayesian modelling, is presented for the Lower Tilemsi region.     

Observational evidence of local turbulence production due to gravity wave saturation in the summer mesosphere

Five foil chaff and two falling sphere rockets flown during the MAC/SINE Campaign on 15 July 1987 at Andenes, Northern Norway (69°17′N). From these rocket measurements, turbulent energy dissipation rates, vertical wind shears and Richardson numbers as functions of height were derived in the range from 82 to 92km. Turbulent energy dissipation rates generally range from 1.4 × 10⁻⁵ to 2.0 × 10⁻²W/kg and are consistent with other experiments performed at the same latitude. Strong wind shears of the order of 50–90 m/s/km are observed at various heights. Good correspondence between turbulence intensity peaks, regions of strong wind shear and low Richardson number is found. Vertical wavenumber spectra of the five scalar winds measured by the foil chaff rockets indicate that there is an excellent agreement with the saturation hypothesis, suggesting that the turbulence intensity peaks measured in this salvo are linked directly to the saturation of gravity wave motions via dynamical instabilities.     

Towards a distinction between digested and undigested glume bases in the archaeobotanical record from Neolithic northern Greece: A preliminary experimental investigation

Abstract

This study investigates the possibility of distinguishing digested from undigested glume wheat chaff in the archaeobotanical record. To this end the contents of dung pellets collected from a goat fed on einkorn spikelet forks and glume bases are analysed and the derived einkorn chaff examined macroscopically with the aid of scanning electron microscopy. The modern dung pellets contained recognisable glume bases which, compared with undigested ones, demonstrated a ‘rugged’ surface. When these dung pellets were charred, glume bases were still preserved in them. The experimental pellets show that dung can contribute glume bases in archaeobotanical assemblages and that these glume bases may be distinguishable from those derived from glume wheat dehusking by-products used as fuel. These results need to be further explored on archaeobotanical materials. Moreover, further experimentation with different charring regimes, as well as the examination of more experimental specimens is needed.     

Transition From Wild to Domesticated Pearl Millet (Pennisetum glaucum) Revealed in Ceramic Temper at Three Middle Holocene Sites in Northern Mali

Imprints of domesticated pearl millet (Pennisetum glaucum (L.) R. Br.) spikelets, observed as temper in ceramics dating to the third millennium BC, provide the earliest evidence for the cultivation and domestication process of this crop in northern Mali. Additional sherds from the same region dating to the fifth and fourth millennium BC were examined and found to have pearl millet chaff with wild morphologies. In addition to studying sherds by stereomicroscopy and subjecting surface casts to scanning electron microscopy (SEM), we also deployed X-ray microcomputed tomography (microCT) on eleven sherds. This significantly augmented the total dataset of archaeological pearl millet chaff remains from which to document the use of the wild pearl millet as ceramic temper and the evolution of its morphology over time. Grain sizes were also estimated from spikelets preserved in the ceramics. Altogether, we are now able to chart the evolution of domesticated pearl millet in western Africa using three characteristics: the evolution of nonshattering stalked involucres; the appearance of multiple spikelet involucres, usually paired spikelets; and the increase in grain size. By the fourth millennium BC, average grain breadth had increased by 28%, although spikelet features otherwise resemble the wild type. In the third millennium BC, the average width of seeds is 38% greater than that of wild seeds, while other qualitative features of domestication are indicated by the presence of paired spikelets and the appearance of nondehiscent, stalked involucres. Nonshattering spikelets had probably become fixed by around 2000 BC, while increases in average grain size continued into the second millennium BC. These data now provide a robust sequence for the morphological evolution of domesticated pearl millet, the first indigenous crop domesticated in western Africa.

     

Preliminary report on the archaeobotanical investigations at Tell Abraq with special attention to chaff impressions in mud brick

Examination of impressions from chaff-tempered mud brick proved rewarding, given the poor preservation of carbonised seed and grain material at Tell Abraq. Individual chaff elements were found to be recognisable from the impressions and it was shown that naked wheat and barley chaff were used as a tempering medium. Charcoal samples indicate that two species of mangrove were present, one of which is no longer found in the area. Tamarisk and Ziziphus were also present. Date charcoal was common. This study remains preliminary, and further sampling and analyses have been planned for the future.     

MINERALOGICAL INVESTIGATIONS OF MEDIEVAL BRICK SAMPLES FROM BÉKÉS COUNTY (SE HUNGARY)

Brick samples from nine archaeological sites representing seven contemporary medieval settlements in Békés County (SE Hungary) were analysed by quantitative X‐ray powder diffraction, optical microscopic, scanning electron microscopic and coupled thermal analytical – evolved gas analytical methods. The aims of this study were to give a mineralogical–petrographical characterization of the brick samples, to gain possible information on the raw clay and the admixed materials, and to determine the firing techniques applied in medieval southeastern Hungary. The mineralogical composition of the samples suggests that the locally extracted clay was mixed with fluvial sand and wheat (Triticum monococcum L.) chaff. The moulded bricks were fired in clamps. The different degrees of calcite consumption suggest that the firing temperature ranged from ～750°C to ～950°C. Moreover, the well‐developed reaction coronas on calcite grains indicate long firing times, lasting perhaps several days.     

What goes in does not always come out: The impact of the ruminant digestive system of sheep on plant material,and its importance for the interpretation of dung-derived archaeobotanical assemblages

Abstract

On archaeological sites where livestock dung was a major fuel source, plant material that survives digestion intact may well be preserved in the remnants of dung-fuelled fires. Preserved plant remains which were derived from dung relate to the diet of animals, and thus provide a way of investigating the agro-pastoral economies of the past. In order to improve our understanding of the taphonomic processes to which plant material is exposed to during digestion, we applied archaeobotanical methods to the analysis of dung from sheep fed a known diet of cereal and wild plant material. Two clear patterns emerge from these investigations. First, cereal material (grain or chaff) survives digestion poorly and was rarely found in the dung analysed. Second, large proportions of seeds of various wild species survive digestion in an identifiable form, probably due to their small size and/or protective coating. These findings are crucial for reliable interpretation of dung-derived plant material in archaeological settings.     

A spectral approach for studying middle and upper atmospheric phenomena

We report on the application of a newly developed spectral code to the study of the middle/upper atmosphere. The spectral approach offers conceptual and practical convenience for analyzing the generation and interaction of different components of atmospheric activity through the decomposition of the dynamical fields into components with different zonal wave numbers (m). As examples and tests, we obtain solutions for the m = 0 (the mean circulation) and 1 (the diurnal tides) components separately (no mutual interactions), as well as the m = 1 component under the influence of the mean circulation. By simulating gravity wave effects with Rayleigh friction and eddy diffusion peaking near 90 km altitude, the mean circulation thus generated can reproduce the observed mesospheric temperature anomaly under solstice conditions. The computed diurnal tides are in good agreement with results obtained earlier by other authors. The large temperature gradient (associated with the m = 0 component) set up by the mesospheric temperature anomaly under solstice conditions creates a condition favorable for the development of baroclinic instabilities in the mesopause layer, especially near the summer pole. In our time dependent calculation, waves with approximately 4-day period are generated in the m = 1 component, superimposing with the 1-day period tides.     

Simulation of ionospheric currents and geomagnetic field variations of Sq for different solar activity

Variations of ionospheric Sq electric currents and fields caused by changes in electric conductivity due to changes in solar activity are studied using the International Reference Ionosphere (IRI) model. Calculations are made for R (sunspot number) = 35 and 200 on the assumption of constant (1, −2)mode tidal winds. It is shown that electric fields grow when solar activity is high, because the ratio of the conductivity in the F-region to that in the E-region increases. Currents in the F-region become stronger than those in the E-region, and nocturnal currents are not negligible when solar activity becomes high. F-region currents also play an important role in the westward currents on the high latitude side of the current vortex. The calculated geomagneticH component at the equator has a depression around 1600 LT for R = 35, while it decreases smoothly from 1100 LT to 1900 LT for R = 200. This difference is consistent with the observed geomagnetic field variation. The ratio of total Sq currents obtained by our simulation is about 3.5, which is a little larger than is found in the observed results.     

On the intrinsic accuracy and precision of luminescence dating techniques for fired ceramics

Luminescence dating techniques have been used extensively for archaeological and geological samples. Such techniques are based on thermally or optically stimulated signals. This paper presents simulations of several luminescence techniques for equivalent dose (ED) estimation for ceramic materials containing quartz. The simulations are carried out using a recently published comprehensive kinetic model for quartz, consisting of 11 electron and hole traps and centers. The complete sequence of the experimental protocols for several thermoluminescence (TL) and optically stimulated luminescence (OSL) techniques are simulated using the same set of kinetic parameters. The specific simulated protocols are: additive dose TL protocol, predose technique (both additive and multiple activation versions), phototransfer protocol, single aliquot regenerative optically stimulated luminescence (SAR-OSL) protocol, and SAR thermoluminescence protocol (SAR-TL). One hundred random variants of the natural samples were generated by keeping the transition probabilities between energy levels fixed, while allowing simultaneous random variations of the concentrations of the 11 energy levels. The relative intrinsic accuracy and precision of the protocols are simulated by calculating the equivalent dose (ED) within the model, for a given natural burial dose of the sample. The intrinsic accuracy of these techniques is estimated by simulating natural irradiation of the samples with a known burial dose, followed by simulation of the luminescence method used to recover the estimated dose ED. The percent difference between the burial dose and the ED value represents the simulated accuracy of the luminescence technique. The relative intrinsic precision of these techniques is estimated by fitting Gaussian probability functions to the ED values obtained with the 100 model variants. It is found that the various techniques can reproduce natural paleodoses in the range 10 mGy–10 Gy with a typical intrinsic accuracy of +1 to 10%. Techniques based on single aliquot protocols were found in general to be more precise than techniques requiring the use of multiple aliquots. In addition, techniques based on interpolation of experimental data were found to be consistently both more precise and accurate than those based on extrapolation of experimental data.     

Recipe for predicting the IMF Bz polarity's change of direction following solar disturbances and at the onset of geomagnetic storms

A three-dimensional, time-dependent, MHD model of solar-disturbance-caused storms (Wu, 1993; Wu et al., 1996a) is used to predict the turning direction of the interplanetary magnetic field (IMF) at Earth. More explicitly, we examine the polarity of B_z caused by solar disturbances on the Sun. Three manifestations of solar disturbances, as studied by previous workers, are examined. Firstly, twenty-nine kilometric Type II events, associated (Cane, 1985) with geomagnetic storms, are studied within the context of our three-dimensional model. Then, an additional eleven long-duration X-ray events (LDEs) with radio fluxes greater than 100 solar flux units were examined; these events were not associated with interplanetary Type II events but were also associated (Cane, 1985) with geomagnetic storms. Finally, in situ interplanetary phenomena that caused ten large (Dst < −100 nT, the intensification of the storm) geomagnetic storm episodes (Tsurutani et al., 1988) near solar maximum are also studied via the B_z predictions of our 3D MHD model. The accuracy of these B_z turning-direction-predictions is found to be as follows: (1) for the kilometric Type II events, the model's prediction was successful for 26 of the 29 events studied; (2) 10/11 for the LDE events; and (3) 7/9 for the major geomagnetic storm events. The overall prediction accuracy of these three independent data sets is 43/49. Thus, consideration of these three independent data sets strongly suggests that the recipe proposed by the basic 3D MHD model may be valid for a zero-th order prediction scheme.     

Comparing different post-IR IRSL approaches for the dating of Holocene coastal foredunes from Ruhnu Island,Estonia

Different post-IR Infrared Stimulated Luminescence (IRSL) approaches are applied to sediments from a Holocene coastal foredune sequence on Ruhnu Island in the eastern Baltic Sea. The comparison of D _e-values and ages determined by the different approaches is complimented by fading and bleaching experiments. The fading experiments imply strong fading of IRSL (50°C) signals and no fading of any of the post-IR IRSL signals, but this is not confirmed by the determined D _e-values. In fact, post-IR IRSL (150°C) D _e-values agree within errors with those calculated for IRSL (50°C). From the bleaching experiments it is inferred that the higher values observed for post-IR IRSL at more elevated stimulation temperatures (225°C/290°C) are likely related to either thermal transfer and/or slow-to-bleach components within the signal. For the dating of the Holocene foredune sequence of Ruhnu Island, the post-IR IRSL (150°C) approach is preferred and these agree with the limited independent age control available from radiocarbon dating. Accordingly, the sequence formed between ca. 7.0 ka and 2.5 ka ago.     

Evidence for non-Maxwellian ion velocity distributions in the F-region

A study has been made of data taken with EISCAT using the Common Program CP-3-C (F-region meridian scan) which shows that regions of enhanced ion temperature (in excess of 3000K at all three EISCAT stations) are found on most days when K_p exceeds 2 or 3, usually accompanied by ion drift velocities of more than 1 km s⁻¹. These periods are often accompanied by anisotropy of the ion temperature and abnormally low apparent electron temperature, consistent with the presence of a non-Maxwellian ion velocity distribution such as would result from large but not exceptional ion drifts. Data for a selected period have been fitted using theoretical ion velocity distributions based on the relaxation collision model and assuming that the ion composition is 100% O⁺. The results confirm the presence of non-Maxwellian distributions, but a detailed comparison with theory reveals some discrepancies, indicating that the analysis may need to be extended to include effects due to, for example, molecular ions and instabilities.     

Plants as material culture in the Near Eastern Neolithic: Perspectives from the silica skeleton artifactual remains at Çatalhöyük

Investigating plants used for building and craft activities is important for understanding how environments surrounding archaeological settlements were exploited, as well as for considering the social practices involved in the creation and use of plant objects. Evidence for such plant uses has been observed at many Near Eastern Neolithic sites but not widely discussed. Survival may occur in a number of ways, including as impressions in clay, and as charred or desiccated macroremains. Another, less well-known, way in which plant artifacts can be found is as silica skeletons (phytoliths). Formed by the in situ decay of plants, their analysis may tell us about taxa exploited, and locations in which plant artifacts were used or discarded. At Çatalhöyük, an abundance of silicified traces of plants used in building materials and for craft activities survive, and are found in domestic and burial contexts. Their analysis demonstrates the routine use of wild plants, especially from wetland areas, for basketry (mats, baskets and cordage) and construction, as well as the secondary use of cereal husk chaff in certain types of building materials. The numerous finds suggest that plant-based containers played an important role as an artifactual class, even after the adoption of early pottery.     

The D e (T,t) plot: A straightforward self-diagnose tool for post-IR IRSL dating procedures

This study presents a new self-diagnose method for the recently developed post-IR infrared stimulated luminescence (pIRIR) dating protocols. This criterion studies the dependence of equivalent dose (D _e) on measurement-temperature (T) and time (t), by applying the D _e (t) analysis to the IRLS and pIRIR signals measured under different temperatures, and combines these D _e (t) plots into one, so-called the D _e (T, t) plot. The pattern of the D _e (T, t) plot is shown to be affected by anomalous fading, partial bleaching and non-bleachable signal. A D _e plateau can be achieved in the D _e (T, t) plot only when the effects of these factors are insignificant. Therefore, this plot can be used as a self-diagnose tool for the validity of pIRIR results. The D _e (T, t) analysis has been applied to four recently developed pIRIR protocols, using aeolian samples with different ages. The results show that this self-diagnose tool can be applied to different pIRIR protocols for validating the pIRIR dating results and evaluating the pIRIR measurement conditions.     

Numerical rise time calculations for obliquely propagating BY pulses

For planning spread spectrum communication systems over ionospheric HF channels it is important to determine pulse rise times or dispersive bandwidths which are characteristic for wideband propagation. 1(n this paper a numerical technique for the calculation of pulse rise times is proposed. This technique has been developed on the basis of known theoretical results concerning the pulse propagation through a plane stratified ionosphere. The calculations were carried out for several cases of propagation through the lower E-region, using the Jones-Stephenson three-dimensional ray-tracing program. The obtained rise times are in the range from a few μs (for the wave-packet reflected from sporadic-E) to several tens of μs (for the wave-packet propagating nearly along the Pedersen path in the lower E-region). The results are shown to be in good agreement with those previously obtained by other authors, either by measurements or theoretical approaches.     

Adaptive separation of regular and irregular magnetic activity for K indices

A numerical data adaptive separation method is developed for the discrimination of quasi-regular magnetic variations from the irregular variations for the determination of the K indices. The method is based on a pattern comparison and discrimination technique using harmonic analyses and is more objective than the hand-scaling method. The wave characteristics of a quiet regular or reference day are compared with those of the disturbed day being examined. The harmonic components that are consistent with those of the reference day are determined by a cosine weighting function. The Fourier coefficients are calculated from these modified harmonics and are then transformed back to the time domain. This ‘regular variation’ is subtracted from the data before the ranges are determined for the semi-logarithmic K scale. The method is tested on digital data from the Canadian magnetic observatories Victoria, Meanook and Ottawa over a 4 month period. The data are at a 10 s sampling interval and encompass the full range of K values (0–9). These K values are compared and checked with hand-scaled values, which were carefully and independently determined from reconstructed magnetograms from the same data. The two methods were found to agree ∼ 97% of the time, with most errors occurring during very irregular periods. This is comparable with values carefully determined by highly skilled observers. It is proposed that the method is suitable for use on a regular basis.