Geophysics
New South Associates (NSA) utilizes state-of-the-art geophysical methods in archaeological surveys.
Have you ever wondered what’s buried below the ground and how it would be possible to know without digging? Well, we have that covered!
Geophysical methods allow us to map potential buried archaeological resources without digging and disturbing the ground or collecting artifacts. Geophysics can be helpful for providing highly detailed information about archaeological sites that can be used to answer research questions, as well as for guiding further investigation such as intensive excavations in targeted areas. Geophysical data can be used to pinpoint the locations of precontact and historic buried features. Evidence of former buildings, rail lines, pit features, foundations, kilns, unmarked graves, and other buried features have been successfully documented by NSA using geophysical methods.
Geophysics Services
NSA was an early adopter of geophysical methods in archaeology and has conducted innovative studies on how these methods can be used in archaeological settings. NSA uses ground-penetrating radar (GPR), magnetic gradiometer, resistivity, and electromagnetic conductivity to investigate the subsurface for our clients.
All of NSA’s geophysical data are mapped with high accuracy real-time kinematic (RTK) GPS systems and/or total stations. NSA strives to ensure that all geophysical results meet the spatial accuracy requirements of our clients.
Ground-Penetrating Radar
GPR works by transmitting pulses of electromagnetic energy (waves) from the surface. The waves reflect off buried objects or features. Reflection strength is used to map below the ground surface, and the results are interpreted by NSA’s experienced geophysical archaeologists. NSA uses GPR at a variety of archaeological sites and cemeteries. GPR can be used in many environments, including urban and rural areas, wooded areas and open fields, and on grass, mulch, and paved surfaces. NSA uses GPR in many settings and site sizes, from small family cemeteries to large, complex landscapes.
Instruments NSA uses:
- GSSI SIR 4000 (200-megahertz [MHz] and 350-MHz HyperStacking antennas/900 and 400-MHz analog antennas)
- MALA MIRA HDR GPR Array
Magnetic Gradiometer
A magnetic gradiometer measures subtle variations in the ground’s magnetism. Cultural activities such as burning and earth moving can cause magnetic variation. NSA uses magnetic gradiometer at precontact and rural early historic sites. It is a great method for covering large areas efficiently and is best suited to rural and undeveloped archaeological sites. The presence of ferrous metals can impact the efficacy of magnetic gradiometer.
Instruments NSA uses:
- Bartington GRAD-601 Dual Fluxgate Gradiometer
- Sensys Magneto MXPDA Five-Sensor Pushcart
Electrical Resistivity
Electrical resistivity measures the ground’s resistance to an electrical current. Archaeological features such as burning or disturbed soils may change the ground’s resistance. NSA uses resistance to map cemeteries and precontact sites. It requires the ground to be accessible to the insertion of small probes.
Instruments NSA uses:
- TAR-3 Resistance Meter
Electromagnetic Conductivity
Electromagnetic conductivity measures the soil’s ability to conduct an electromagnetic current. Soil disturbances or archaeological features can cause contrast in the soil’s resistance. Cultural activities, such as digging graves, pits, constructing floors and buildings, or modifying the landscape, can cause increased or decreased conductivity from the surrounding soils.
Instruments NSA uses:
- Geonics Limited EM38 Conductivity Meter