Archaeological Geophysics and Geochemistry Earthsound carry out geophysical and geochemical surveys to evaluate the unseen archaeology of a site beneath the soil. A geophysical assessment, which identifies the extent of archaeology across a site, is often required as part of a planning application or environmental impact assessment. Archaeological site assessments occur in advance of various development projects such as road or pipe corridors, a single house or estates, industrial zones or mineral extraction sites. We also carry out site research and monument delimiting surveys, to assess the preservation and extent of known archaeology. Earthsound have assessed sites on behalf of a wide range of clients including archaeological contractors, architects, engineers, developers, government agencies and individuals. Our resources, facilities and expertise offer clients a reliable service that produces cost effective solutions within strict time limits. There are a number of different geophysical and geochemical techniques, which can suit the varied circumstances unique to each project, such as the type of archaeology being sought, the geology of the area and the size of the site. Our qualified geophysicists will be able to advise you on the most suitable technique to meet your needs. Geophysical Surveys Geochemical Surveys Geophysical Surveys Geophysical surveys can be used to assess: Commercial / Industrial Developments Housing Development (both large and small scale) Road/Pipe Corridors Mineral Extraction Sites Research Sites Geophysical surveys are divided into two broad techniques, reconnaissance and detailed survey types. These techniques can often be used together, especially over large areas such as road/pipe corridors. Reconnaissance techniques, such as Magnetic Susceptibility, provide a broad assessment of archaeological activity across a site, such as zones of magnetic enhancement that indicate areas influenced by human occupation. The results of a reconnaissance survey are used to target areas for more detailed geophysical techniques. Detailed survey techniques, such as Magnetic Gradiometer, Earth Resistance, Ground Penetrating Radar (GPR) and Electromagnetics, identify discrete archaeological features such as ditches, pits, walls, souterrains, hearths and kilns. Each technique measures variations in the magnetism and/or electrical conductance of the soil, which suggests trends and anomalies that represent different types of archaeological features under the soil. Magnetic Susceptibility Magnetic susceptibility is a reconnaissance technique which assesses the magnetism of the topsoil - an indicator of human intervention - an ideal method for locating areas of Burning Industry Occupation sites Field systems Soil variations Zones of potential archaeology (blue/red) This is a rapid method suitable for a preliminary assessment of large sites, which can be used to develop a detailed geophysical strategy. Magnetic susceptibility surveys can also be used within an excavation context, mapping the susceptibility content of individual features. Earthsound often supplement other survey techniques, such as magnetic gradiometer, with magnetic susceptibility surveys, as they are a useful indicator of archaeological trends. Magnetic Gradiometer Magnetic gradiometer survey is the most frequently used geophysical technique in Ireland, allowing rapid mapping of magnetic anomalies contained within the sub-soil, which can represent archaeological features. Magnetic gradiometer surveys are ideal for detecting Ditches Hearths Pits Burnt or fired remains A number of different magnetometers can be used including Fluxgate Gradiometers and Caesium Vapour magnetometers These surveys can be conducted at a range of sample intervals, which allows for the detection of small features such as post-holes. Relict field systems Medieval town remains   Earth Resistance This technique can be used to complement magnetic gradiometer surveys and as a survey method in its own right. An earth resistance survey measures the resistance or conductance of the ground to an electrical current, mapping areas of differing moisture content, which can represent archaeological features such as ditches, souterrains or structures. Ringfort Earth resistance surveys allow for the detection of Stone or stone-filled features Ditches Pits Ponds Electrical Resistivity Tomography ERT is a form of earth resistance survey that records depth information across a feature or over a survey area. ERT Surveys are able to provide information on deeply buried archaeological remains or multiphase sites such as surfaces, water courses or buried walls. This technique allows cross section and stratigraphic information to be gained about archaeological and landscape features. ERT surveys allow for the assessment of features such as Souterrains Ditches Walls Structures Water features Mounds Cavities / Voids / Caves   Souterrain (red/purple)   Ground Penetrating Radar Ground Penetrating Radar (GPR) is a prospection method which allows depth information to be gained. Capable of detecting multiple buried layers at depth, this instrument can be used to assess archaeological remains in section or in plan and can also be used in urban areas covered by tramac or concrete, for example under roads or within buildings. Ground Penetrating Radar can detect a large number of possible archaeological features including Voids - caves, tomb shafts etc Souterrains Masonry Ditches Ditch and wall foundations under a reinforced concrete floor Metal Detection Survey Metal detectors can prove an invaluable tool for archaeological investigations. Capable of detecting and identifying metallic items within the ground this equipment can be used prior to archaeological investigation as part of a field assessment or field walking. It can also be used as part of a recovery scheme within excavations and/or scanning unexcavated contexts and spoil heaps for metallic finds. Allowing fast data collection with either immediate results or find position plotting via GPS this survey can detect metallic items such as Nails Coins Jewelry Military items - musket shots, cannon, swords etc   Distribution map of metal finds located through metal detecting Electromagnetic Survey Electromagnetic (EM) methods, as the technology develops, are being used in archaeological and environmental prospection. These methods cover a range of different instruments which all use electromagnetic waves to detect buried remains as either profiles or maps. These instruments are designed for fast data collection and can be combined with an onboard Global Positioning System (GPS), being either hand held or sled-drawn and are ideal for the detection of Voids - caves, tomb shafts etc Souterrains Iron Workings Ditches Structures Profile across a barrow showing a compacted central core and surrounding ditches Geophysical Survey Requirements If you would like to contact us for a quotation, the following information would be useful to help us accurately assess your needs and requirements: Size and Shape of Survey area Purpose of Survey Survey Location Ground Conditions - e.g. Pasture, Crop or Tarmac Other useful information includes maps of the site, the location of any structures in the survey area and any geological information. Contact Details Earthsound Archaeological Geophysics Prospect House Drumagh Claremorris County Mayo Ireland Tel: +353 (0) 94 936 2228 Geochemical Surveys Earthsound is able to offer a wide range of laboratory analysis services. Soil samples collected from archaeological sites can be analysed for physical and chemical variations suggestive of archaeological or anthropogenic activity, and complement both excavated evidence and geophysical surveys. By integrating geochemical analysis with on-site archaeological research, we can answer fundamental questions and build up a detailed picture concerning the use and development of an archaeological site. Earthsound's facilities provide an extensive range of routine and non-routine testing, research and related capabilities to a wide range of contractors and consultancies. Laboratory capabilities range from chemical analysis, physical properties testing and quality control to advanced materials analysis. Prospection Soil samples can be used across a large area as a prospection technique, to examine archaeologically unknown sites, or in post-excavation, to assess individual contexts for chemicals that may suggest burning, skeletal evidence, urine or faeces. Earthsound's systematic collection of multiple topsoil samples across a site can identify previously unknown features and trends suggestive of archaeology. Investigation By targeting excavated features such as half-sections of pits, ditches, graves, kilns, hearths or other individual contexts, we can appreciate how a site was used over time and identify context functions which may not be appreciable to the naked eye, such as hearths, burning, metallurgical activity, human burials and cremations, areas of refuse dumping, animal habitation, industry, and anthropogenic influences on soil formation and manipulation. Geochemical analyses can help clarify information where no internal/external architectural features remain, such as cess-pits, animal stalls, cooking and industrial areas. Geochemical soil samples can be collected by Earthsound technicians or by archaeological site staff. Each sample needs to be collected under controlled conditions to avoid potential cross-contamination - we can advise you on how best to achieve this and which technique(s) are appropriate to answer your project requirements. We also provide onsite tutorials to archaeological staff, on a one-to-one basis or in a group, for sampling strategies and best practice. The following laboratory work can be carried out Carbonate analysis Conductivity Heavy Metal analysis Loss on Ignition analysis (organic content) Magnetic Susceptibility content Particle Size analysis Phosphate analysis pH analysis Carbonate analysis Carbonates are inorganic remains that can indicate levels of human occupation across a site. The weight loss of heated carbon dioxide and ash components reflects the carbonate content of the soil as a percentage. Conductivity The electrical conductivity (or its inverse, resistivity), of a soil reflects it's moisture content. The moisture content is usually a direct reference to water flow and can be a useful indicator of paleochannels, and wet features such as sluices, tanning-pits, cess-pits and wetland. Heavy Metal analysis Heavy Metal analysis can be used to identify areas of human habitation, particularly suited to land which is unavailable for field walking e.g. pasture fields. Concentrations of human activity and occupation results in the accumulation of heavy metals including copper, lead and zinc. Depending upon project requirements different metals can be tested. This methodology can be especially useful in rural aceramic sites where a lack of diagnostic material exists. Loss on Ignition Sequential loss on ignition (LOI) is a common and widely used method to estimate the organic and carbonate content of sediments. Organic matter is oxidised at high temperature to carbon dioxide and ash. The weight loss during the reaction reflects the organic content of the soil as a percentage. The organic content of a soil can indicate the use of features such as pit / ditch fills.   Magnetic Susceptibility Magnetic susceptibility is widely used as an archaeological prospection methodology to assess anthropogenic activity within a subsoil, either in advance of detailed surveys or as a complement to them. A soil is measured for its susceptibility to an induced magnetic field, which can reveal levels of magnetic enhancement that can reflect, amongst other things, burning (discriminating between domestic and industrial burning) and occupation areas. Particle Size analysis The distribution of particle size determines the texture of the soil - whether it is predominantly sandy, loamy or clayey and is an important criteria for identifying depositional environments.   Phosphate analysis Phosphorous is an abundant element, contained within the body and excreted by animals and humans in the form or urine and fecal material. Analysis of phosphates can allow for the detection of a number of archaeological features, including habitation areas, animal husbandry pens, manure in soils and in some cases burial sites. This can be especially useful in determining the former presence of bones in pits on acidic soils. Geophysical applications may complement phosphate data in many cases, or in some situations act as an alternative method of prospection. pH analysis pH analysis determines the alkalinity or acidity of a soil which can be useful in determining the function of occupational / industrial contexts. Geochemical Survey Requirements If you would like to contact us for a quotation the following information would be useful to help us accurately assess your needs and requirements: Purpose of Survey Number of contexts/features or area requiring analysis Survey Location Ground conditions (for reconnaissance surveys only) Contact Details Earthsound Archaeological Geophysics Prospect House Drumagh Claremorris County Mayo Ireland Tel: +353 (0) 94 936 2228 | Archaeological Geophysics & Geochemistry | Geological Surveys | Environmental Surveys | Topographical Surveys | GPS Setting Out | Waterborne Surveys | Cultural Resource Management | Digital Graphics | Research & Development | Publications & Presentations | Education & Training | Project Management |