Spatially resolved texture analysis of Napoleonic War era copper bolts

The spatial resolution achievable by a time-of-flight neutron strain scanner has been harnessed using a new data analysis methodology (NyRTex) to determine, nondestructively, the spatial variation of crystallographic texture in objects of cultural heritage. Previous studies on the crystallographic texture at the centre of three Napoleonic War era copper bolts, which demonstrated the value of this technique in differentiating between the different production processes of the different types of bolts, were extended to four copper bolts from the wrecks of HMS Impregnable (completed 1786), HMS Amethyst (1799), HMS Pomone (1805) and HMS Maeander (1840) along with a cylindrical `segment' of a further incomplete bolt from HMS Pomone. These included bolts with works stamps, allowing comparison with documentary accounts of the manufacturing processes used, and the results demonstrated unequivocally that bolts with a `Westwood and Collins' patent stamp were made using the Collins rather than the Westwood process. In some bolts there was a pronounced variation in texture across the cross section. In some cases this is consistent with what is known of the types of hot and cold working used, but the results from the latest study might also suggest that, even in the mature phase of this technology, some hand finishing was sometimes necessary. This examination of bolts from a wider range of dates is an important step in increasing our understanding of the introduction and evolution of copper fastenings in Royal Navy warships

EAC Guidelines for the use of Geophysics in Archaeology: Questions to Ask and Points to Consider.

These guidelines provide an overview of the issues to be considered when undertaking or commissioning geophysical survey in archaeology. As every project diff ers in its requirements (e.g. from fi nding sites to creating detailed maps of individual structures) and variations in geological and environmental conditions lead to diff erent geophysical responses, there is no single ‘best’ survey technique or methodology. Th is guide, in its European approach, highlights the various questions to be asked before a survey is undertaken. It does not provide recipebook advice on how to do a geophysical survey or a tick list of which technique is suitable under what conditions. Experienced archaeological geophysicists should be consulted to address the questions that are being posed. Using geophysical techniques and methods inappropriately will lead to disappointment and may, ultimately, result in archaeologists not using them at all. “If all you have is a hammer (or magnetometer), driving a screw becomes impossible”. Especially in the American literature the term ‘remote sensing’ is oft en used to describe geophysical as well as air and space based exploration of underground features (e.g. Wiseman and El-Baz 2007). By contrast, and in line with European traditions, a clear distinction is made here between ground-based geophysical techniques and remote sensing techniques. Th is is based on the imaging principles underlying the respective technologies. Ground based systems usually collect one spatially registered data sample from each sensor location (e.g. a single reading for each magnetometer, or a single trace from each GPR antenna). Remote sensing techniques, by contrast, collect spatially resolved data from a whole area of investigation from each sensor location, using either the system’s optical aperture (e.g. photography) or a scanning device (e.g. laser sampling). These guidelines are based on the experience of the authors in archaeological geophysics and infl uenced by various published sources

Localization of magnetic sources underground by a data adaptive tomographic scanner

A tomography method is proposed to image magnetic anomaly sources buried below a non-flat ground surface, by developing the expression of the total power associated with a measured magnetic field. By discretising the integral relating a static magnetic field to its source terms, the total power can be written as a sum of crosscorrelation products between the magnetic field data set and the theoretical expression of the magnetic field generated by a source element of unitary strength. Then, applying Schwarz's inequality, an occurrence probability function is derived for imaging any distribution of magnetic anomaly sources in the subsurface. The tomographic procedure consists in scanning the half-space below the survey area by the unitary source and in computing the occurrence probability function at the nodes of a regular grid within the half-space. The grid values are finally contoured in order to single out the zones with high probability of occurrence of buried magnetic anomaly sources. Synthetic and field examples are discussed to test the resolution power of the proposed tomography.Comment: 15 pages, 17 figure

GEOPHYSICAL EVALUATION OF FOUR AREAS WITHIN THE TRADE FAIR LOCALITY AT PECOS NATIONAL HISTORICAL PARK, SAN MIGUEL COUNTY, NEW MEXICO

The geophysical survey of the four selected areas within the Trade Fair Locality at Pecos National Historical Park was conducted between June 24 and 30, 2012. The Midwest Archeological Center provided technical assistance for the geophysical investigations of the four geophysical project areas. The geophysical investigations consisted primarily of a magnetic survey with a dual fluxgate gradiometer. A limited conductivity survey with an electromagnetic induction meter was also conducted on two of the four geophysical project areas. An area equal to 8,876 m2 or 2.19 ac was surveyed during the geophysical investigations of the four geophysical project areas. The geophysical survey resulted in the identification of numerous subsurface archeological features associated with the Pecos Pueblo occupation, historic Spanish and American activities, and the modern National Park Serv ice use of the property

Técnicas de excavación en yacimientos paleolíticos. Algunos casos de estudio

Les tècniques d’excavació utilitzades en jaciments arqueològics poques vegades s’especifiquen en les publicacions acadèmiques, sota l’entesa tàcita que els mètodes de treball de camp estan prou estandarditzats per fer-ne la descripció innecessària. No obstant això, tot i que aquest és probablement el cas de l’arqueologia d’urgència, és una suposició injustificada pel que fa a l’arqueologia acadèmica, i deixa de banda l’àmplia gamma de diferents tècniques de camp utilitzades durant les excavacions arqueològiques per cada equip d’investigació. En aquest treball presentem els mètodes de camp utilitzats pel nostre grup de recerca en l’excavació de jaciments paleolítics a Espanya i a l’Àfrica oriental, des de la selecció dels llocs per a l’excavació fins al processament digital de les dades espacials i arqueològiques resultants. El nostre objectiu és contribuir a la consolidació d’un corpus de pràctiques estandarditzades en les excavacions acadèmiques modernes el control de qualitat de les quals és essencial per garantir l’èxit de la recollida de les dades utilitzades per a la interpretació de les restes arqueològiques.Field techniques used in the excavation of archaeological sites are rarely specified in academic publications, under the tacit understanding that fieldwork methods are standardized enough to make their description unnecessary. Although that is probably the case in commercial archaeology, it is however an unwarranted assumption as far as academic archaeology is concern, and neglects the wide range of different field techniques used during archaeological excavations by each research team. In this paper, we outline field methods used by our research group in the excavation of Palaeolithic sites in Spain and East Africa, from the selection of localities for excavation to the digital processing of the resulting spatial and archaeological data. Our aim is to contribute to consolidating a corpus of standard practices in modern research archaeological excavation, whose quality control is essential to guarantee a successful collection of data used for the interpretation of archaeological remains.Las técnicas de excavación utilizadas en los yacimientos arqueológicos rara vez se especifican en las publicaciones académicas, bajo el entendimiento tácito de que los métodos de trabajo de campo están suficientemente estandarizados para hacer su descripción innecesaria. Sin embargo, aunque éste es probablemente el caso de la arqueología de urgencia, es una suposición injustificada en cuanto a la arqueología académica, y obvia la amplia gama de diferentes técnicas de campo utilizadas durante las excavaciones arqueológicas por cada equipo de investigación. En este trabajo presentamos los métodos de campo utilizados por nuestro grupo de investigación en la excavación de yacimientos paleolíticos en España y África oriental, desde la selección de los sitios para la excavación hasta el procesado digital de los datos espaciales y arqueológicos obtenidos. Nuestro objetivo es contribuir a la consolidación de un corpus de prácticas estandarizadas en las excavaciones académicas modernas, cuyo control de calidad es esencial para garantizar el éxito en la recogida de los datos utilizados para la interpretación de los restos arqueológicos

Archaeological fieldwork techniques in Stone Age sites : some case studies

Field techniques used in the excavation of archaeological sites are rarely specified in academic publications, under the tacit understanding that fieldwork methods are standardized enough to make their description unnecessary. Although that is probably the case in commercial archaeology, it is however an unwarranted assumption as far as academic archaeology is concern, and neglects the wide range of different field techniques used during archaeological excavations by each research team. In this paper, we outline field methods used by our research group in the excavation of Palaeolithic sites in Spain and East Africa, from the selection of localities for excavation to the digital processing of the resulting spatial and archaeological data. Our aim is to contribute to consolidating a corpus of standard practices in modern research archaeological excavation, whose quality control is essential to guarantee a successful collection of data used for the interpretation of archaeological remains.Les tècniques d'excavació utilitzades en jaciments arqueològics poques vegades s'especifiquen en les publicacions acadèmiques, sota l'entesa tàcita que els mètodes de treball de camp estan prou estandarditzats per fer-ne la descripció innecessària. No obstant això, tot i que aquest és probablement el cas de l'arqueologia d'urgència, és una suposició injustificada pel que fa a l'arqueologia acadèmica, i deixa de banda l'àmplia gamma de diferents tècniques de camp utilitzades durant les excavacions arqueològiques per cada equip d'investigació. En aquest treball presentem els mètodes de camp utilitzats pel nostre grup de recerca en l'excavació de jaciments paleolítics a Espanya i a l'Àfrica oriental, des de la selecció dels llocs per a l'excavació fins al processament digital de les dades espacials i arqueològiques resultants. El nostre objectiu és contribuir a la consolidació d'un corpus de pràctiques estandarditzades en les excavacions acadèmiques modernes el control de qualitat de les quals és essencial per garantir l'èxit de la recollida de les dades utilitzades per a la interpretació de les restes arqueològiques.Las técnicas de excavación utilizadas en los yacimientos arqueológicos rara vez se especifican en las publicaciones académicas, bajo el entendimiento tácito de que los métodos de trabajo de campo están suficientemente estandarizados para hacer su descripción innecesaria. Sin embargo, aunque éste es probablemente el caso de la arqueología de urgencia, es una suposición injustificada en cuanto a la arqueología académica, y obvia la amplia gama de diferentes técnicas de campo utilizadas durante las excavaciones arqueológicas por cada equipo de investigación. En este trabajo presentamos los métodos de campo utilizados por nuestro grupo de investigación en la excavación de yacimientos paleolíticos en España y África oriental, desde la selección de los sitios para la excavación hasta el procesado digital de los datos espaciales y arqueológicos obtenidos. Nuestro objetivo es contribuir a la consolidación de un corpus de prácticas estandarizadas en las excavaciones académicas modernas, cuyo control de calidad es esencial para garantizar el éxito en la recogida de los datos utilizados para la interpretación de los restos arqueológicos

Exploration and reduction of data using principal component analysis

In a data set with two variables only, a scatterplot between the two variables can be easily plotted to represent the data visually. When the number of variables in the data set is large, however, it is more difficult to represent visually. The method of principal component analysis (PCA) can sometimes be used to represent the data faithfully in few dimensions (eg. three or less), with little or no loss of information. This reduction in dimensionality is best achieved when the original variables are highly correlated, positively or negatively. In this case, it is quite conceivable that 20 or 30 original variables can be adequately represented by two or three new variables, which are suitable combinations of the original ones, and which are called principal components. Principal components are uncorrelated between themselves, so that each component describes a different dimension of the data. The principal components can also be arranged in descending order of their variance. The first component has the largest variance, and is the most important, followed by the second component with the second largest variance, and so on. The first two components can then be evaluated for each case in the data set and plotted against each other in a scattergraph, the score for the first component being plotted along the horizontal axis, the score of the second component being plotted on the vertical axis. This scatterplot is a parsimonious two-dimensional picture of the variables and cases in the original data set. We illustrate the method by applying it to simulated datasets, and to a dataset containing national track record times for males and females in various countries.peer-reviewe