Magnetic Gradient Surveys (aka Magnetometer Surveys)
Magnetometers are the most versatile of the geophysical instruments available to archaeologists. They are highly portable, very fast, and sensitive enough to detect even very subtle prehistoric Native American features thousands of years old. While some might argue that magnetometers are not as useful on historic-era sites because of the magnetic clutter (metal) at these sites, in reality magnetic surveys can be quite revealing at most kinds of historic-era sites, including farmsteads, urban sites, and industrial sites.
FM 256 Fluxgate Gradiometer (a type of magnetometer) made by Geoscan Research. Handheld system that is very maneuverable. Good for cemeteries, woodlots, and areas with many obstacles.
Survey in Old Washington Cemetery, Washington Court House, Ohio
Foerster Ferex-DLG 4.032 4-probe fluxgate magnetometer system with a cart. Very speedy! Excellent for open fields (hay fields, harvested bean fields, or mowed corn stubble). It really is four times faster!
Surveying at Cahokia Mounds, a World Heritage site in southern Illinois.
Examples of Magnetic Gradient Surveys
- Prehistoric Native American Residential Sites (e.g., villages and camps)
- Prehistoric Native American Earthworks and Mounds
- Historic-era Graves and Cemeteries
- Historic-era Farmsteads
- Other Historic-era Settings, Building and Structure Foundations
- Urban Lots and Industrial Sites