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Integration of different kinds of data is an important issue in archaeological prospection. However, the current methodological approaches are underdeveloped and rarely use the data to their maximum potential. Common approaches to integration in the geophysical sciences are mostly just various forms of comparison. We argue that true integration should involve the mathematical manipulation of input data such that the original values of the input data are changed, or that new variables are produced. To address this important research gap, we present an innovative approach to the analysis of geochemical and geophysical datasets in prospection-focused disciplines. Our approach, which we refer to as "multiscalar integration" to differentiate it from simpler methods, involves the application of mathematical methods and tools to process the data in a unified way. To demonstrate our approach, we focus on integrating geophysical data (magnetometry) with geochemical data (elemental content). Our approach comprises three main stages: Quantification of the data deviation from random distributions, linear modelling of geophysical and geochemical data and integration based on weighting of the different elements derived in previous steps. All the steps of the workflow can be also applied separately and independently as needed or preferred. Our approach is implemented in the R environment for statistical computing. All data, functions and scripts used in the work are available from open access repositories (Zenodo.org and Github.com) so that others can test, modify and apply our proposed methods to new cases and problems. Our approach has the following advantages: (1) It allows the rapid exploration of multiple data sources in an unified way; (2) it can increase the utility of geochemical data across diverse prospection disciplines; (3) it facilitates the identification of links between geochemical and geophysical data (or generally, between point-based and raster data); (4) it innovatively integrates various datasets by weighting the information provided by each; (5) it is simple to apply following a step-by-step framework; (6) the code and workflow is fully open to allow for customization, improvements and additions. [ABSTRACT FROM AUTHOR]

Spatial information on soils generally results from local observations that are destructive and time consuming especially in the case of heterogeneous soils. Geophysical technics can be a great help for soil mapping since they are non-destructive and fast. Large areas can be surveyed with a high density of measurements. Electrical resistivity is particularly interesting for soil study because it covers a wide range of values (several decades) and depends on many characteristics of the soil. The main objective of this paper was to study soil spatial variability using an original approach to electrical data processing. Electrical data from a 3-depth survey, usually treated as three apparent resistivity maps, were considered as many electrical soundings each with three apparent resistivity values. The study of the vertical succession of these values led to define nine reference geophysical taxa. This taxonomy relies on a parameter (α) which discriminates soil layers and is defined as the interval (in Ωm) beyond which two successive apparent resistivity values on a sounding are considered different. Geophysical taxa mapping highlighted their spatial coherence, which was related to pedological characteristics such as the presence of a clay layer or the depth of the soil profile. The comparison between the spatial distribution of geophysical taxa and a pre-existing soil map showed that the delineations of taxa clusters closely matched soil unit boundaries but were much less smooth. This method allowed the assignment to each soil type of a specific apparent electrical resistivity profile which was consistent with soil profile description. The method is straightly applicable to data from other surveys, and opens the way to the development of semi-automatic soil mapping from electrical resistivity data. [ABSTRACT FROM AUTHOR]

Abstract: Electromagnetic induction (EMI) is one of the geophysical techniques widely used in soil studies, the slingram devices being held horizontally over the soil surface, i.e. with the coils located at the same height above the ground surface. Our study aims assessing the abilities of slingram devices when held vertically. 1D and 3D modelling have been achieved in order to compare the theoretical responses of vertical devices to the horizontal ones. Some comparative surveys were also undertaken in archaeological contexts to confirm the reliability of theoretical conclusions. Both approaches show that vertical slingram devices are suitable for survey and can constitute an alternative to the usual horizontal orientation. We give a table in Appendix A which contains the calibration coefficient allowing transforming of the values given by some of commercially available devices which would be advantageous to use in vertical orientation [Copyright &y& Elsevier]

Abstract: Logging opens wide paths for cyclostratigraphic studies of sedimentary successions. In clay-dominated rocks, magnetic susceptibility (MS) is very informative and the quality of the results can be further enhanced by deconvolution, where the deformation of the original susceptibility versus depth variation by the instrument is filtered out by its impulse response (thin layer response). This is illustrated by processing the data acquired in the PEP1002 borehole (Bure, Meuse, France) using two coils 0.25m apart where high-frequency, 0.5 to 0.8m, period precession cycles (21kyr) can be identified, as well as the 2.5 to 4m period eccentricity (95kyr) ones. [Copyright &y& Elsevier]

This article addresses the characterization of resistive archaeological targets and near surface structures by electromagnetic induction (EMI). It presents tests achieved with the DualEM-421S instrument (Dualem Inc., Milton, Canada) in order to be able to quantitatively compare these measurements to the standard technique of direct-current (d.c.) resistivity. The test was done over the Gallo-roman site of Vieil-Evreux in Normandy, France and one-dimensional (1D) and three-dimensional (3D) inversions were applied to the data set obtained. We have first investigated the signal-to-noise ratio of each of the six DualEM receiver coils both in a static mode and for a quad-pulled system. The dependence on the roll angle was also measured and it is shown that rotation of DualEM must be taken into account if the roll angle is more than ±10°. Absolute calibration and in-phase/quadrature (out of phase) component discrimination was checked by measuring the response of a small conductive and non-magnetic sphere. Several electromagnetic soundings by measuring the instrument response at different heights were done in order to check the quadrature (out-of-phase) response of the instrument. Inversions of these electromagnetic soundings were compared to d.c. vertical electric soundings (VESs) over four locations and found in accordance. Several maps using different coil configurations (HCP, VCP, PERP) and different heights were performed and inverted, both for a wide mesh (5 m) and for a finer one (0.5 m). The wide mesh allows a global and rapid description of the surface geology context (continuous d.c. measurements cannot deliver equivalent depth of investigation). The fine mesh conductivity maps clearly show the walls of a fanum (temple) as well as other structures and prove that the DualEM-421S is able to map correctly archaeological resistive targets. These maps and their interpretations were compared to previous results obtained by d.c. technique. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Measuring magnetic viscosity significantly improves the information brought by the magnetic susceptibility about the history of soils. In the field its mapping can be achieved by TDEM measurement. Here we study the applicability of multi-frequency FDEM viscosity measurement in the low frequency range using a commercial EMI instrument. The dependence of the in-phase and quadrature out-of-phase components of the ratio of secondary magnetic field to primary magnetic field, electrical conductivity, magnetic susceptibility and magnetic viscosity is first described. The procedure allowing the determination of the three apparent properties is then proposed. It delivers first the conductivity using the differences between the quadrature responses at two different frequencies. Then, after removing the conductivity effects both in the in-phase and quadrature components, it provides the values of the magnetic susceptibility and viscosity. This procedure is tested on 1D and 3D synthetic cases to assess any arising uncertainty. The application of the method is attested in two archaeological case histories in Thessaly in conductive and magnetic soil contexts. The apparent magnetic viscosity maps are significantly different from magnetic susceptibility and conductivity maps thus bringing new information into the game. [ABSTRACT FROM AUTHOR]

Abstract: Geophysical survey by Automatic Resistivity Profiling (ARP©) system of the Pierrelaye–Bessancourt area revealed remarkable conductive polygon patterns of 20- to 30-m diameter detected between 0.5- and 1.7-m depth. Trenches dug down to the limestone substrate allowed detailing of the pedological and lithological units that compose such polygonal features. The patterns are formed by greenish glauconite and carbonated sand hollows where clay-rich pedological horizons bend downward, forming narrow tongs extending up to 2- to 3-m depth. Such structures were interpreted as a buried polygonal ice-wedge network (thermokarst depressions). Geometrical relationships between the lithological units and consecutive erosional surfaces allowed the identification of successive landscape events and a landscape chronology. The sequence started during the Saalian glaciation with (1) the development of patterned grounds by thermokarstic cryoturbation; (2) the consecutive deflation/erosion during post-permafrost aridity; (3) the loess and eolian sand deposits; (4) the weathering of the former deposits with development of pedogenic horizons during the Eemian interglacial; (5) the recurrent cryoturbation and thermal cracking leading to infolding of the pedogenic horizons during the Pleniglacial optimum (Weichselian); and finally (5) the erosion that levelled the periglacial microreliefs, most probably during the last glacial stage (Weichselian), leading to the modern landscape. In this agricultural area, urban waste water has been spread for more than 100years by flooding irrigation for food crop production and has led to high levels of metal pollution in the surface horizons of the soils. The polygonal cryogenic structures have major impacts on soil hydrology and dispersion/distribution of heavy metals toward the geological substrate. Such structures are essential to consider when conceiving proposals for future soil management of this polluted area. [Copyright &y& Elsevier]

ABSTRACT Statute laws concerning preventative archaeology adopted in France in 2001 for threatened sites required development of evaluation techniques. The common methodology used during the past 10 years has been extensive excavation. This method delivers a direct record of the discovered archaeological features and of their distribution. However, the success of visual observation can be variable, depending on geological context and the feasibility of envisaging the entire archaeological settlement from the part that is observed. We report here a case study from an early Middle Age settlement located on a floodplain. It was partially excavated and the alluvial context makes the features difficult to recognize for archaeologists. We show how the geophysical survey complemented the archaeological survey and allowed the detection of previously unrecognized features. In a second step, we compare the results of surveys with magnetic and electromagnetic methods on a topsoil stripped area and the neighbouring surface. From this analysis we conclude that a significant part of the unrecognized features discovered were present above the level of stripping. This example underlines that the practice of topsoil stripping has to be reconsidered, and should be integrated with geophysical survey to limit the potential loss of archaeological information. Copyright © 2012 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Water management enabled the development of ancient societies allowing them to ensure agropastoral production and manufacturing activities. In the Andes, near the shore of Lake Titicaca, the city of Tiwanaku (Bolivia) is one of the largest pre-Hispanic urban centres in South America. Abrupt climate changes in the high-altitude Altiplano during the late Holocene likely forced the population to develop water management strategies. So far, knowledge concerning the existence of a water network around the city of Tiwanaku is limited to hypotheses derived from surface and aerial observations. In this study, geoscience techniques (morphology, geophysics, sedimentology and chronostratigraphy) helped to reconstruct the canals' morphology and their flow dynamics, along with their chronology of operation in a context of hydroclimatic change. Two ca. 30 m large canals bypassing the monumental core and supplied by a shallow water table and multiple tributaries, connected the agricultural and the urban areas. The structure and organization of the network testify to an elaborate knowledge of the local hydrology by the former builders of the city. It ensured water supply and flood management in relation to the extreme intra- and inter-annual variability of precipitations in the central Andes. The palaeogeographical and landscape reconstruction demonstrates that canals were set from natural features during the early Late Formative period (200 BCE to 200 CE) during a wet period likely for water resource management needs. During the Tiwanaku state (before 800 CE), the filling of the canal network with soil and sediment suggests a major change in its use, and possibly its partial abandonment, during a major restructuration of the site, in a period of increased regional precipitation. • The city of Tiwanaku is one of the largest pre-Hispanic centres in the Americas. • A sophisticated water network was characterized with geoscientific tools. • The network was supplied by outcropping water tables and tributaries. • It was built from existing channels between 200 BCE to 300 CE during a wet period. • Reorganization occurred before 800 CE with a partial abandonment of the canals or a major change in their use. [ABSTRACT FROM AUTHOR]