Archaeological Geophysics
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Worthington, MN                 

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Anecdotal information suggested that a prehistoric site, possibly a village, existed on a bluff overlooking Lake Ocheda, a few miles outside of Worthington, Minnesota.  The property has been family owned for a hundred years and none of them had ever plowed it because access was impeded by a drainage and associated wetland.  It was an ideal site  for archaeology and geophysics. Magnetometer and resistance surveys were conducted as part of a thesis project for a student at Minnesota State University at Mankato. Don Johnson assisted the project by providing the geophysical equipment and helping with the geophysical survey.

 

Worthington Magnetics

Magnetometer data were collected as vertical gradient.  For the most part, the white spots (magnetic highs) in this image indicate metal.  Several were tested by excavating and bits of metal were found. Since this was supposed to be undisturbed (in historic times), the presence of metal was somewhat puzzling.  The area between about 30 to 60 East and 10 to 35 North appears generally disturbed and has some of the strongest (metal) responses.  Anomalies along the south edge of the map is related to bits of metal along the property line and fence.  Blank areas in the middle of the survey were due to fallen trees and a thicket.

Worthington Resistance

In addition to showing natural resistance variations across the site, the data also shows what appear to be a rectangular structure.  Again this is not what was expected from an undisturbed prehistoric site.  The rectangular anomaly is a resistance high centered at about 45 East and 25 North, which is located within the disturbed area mapped by the magnetometer survey.

Excavations

Excavations at the site found bricks that may either be the base of a chimney or the corner of a historic building.  Whatever the function, it showed that the site has been used in historic times, probably the latter part of the 19th century.  The bricks are thought to be the remains of a sod house, some of which used bricks to provide strength in the corners.  Although the site is not an undisturbed prehistoric site, it is an excellent opportunity to study an early pioneer site in the area.  The site is not yet fully studied.