Archaeo-Physics, LLC - geophysical survey and subsurface mapping

Case Study

Central Park

19th Century brewery complex, Grand Forks, North Dakota

An electrical resistance survey was performed in Central Park, Grand Forks, North Dakota. The purpose of the survey was to locate and assess the integrity of archaeological features in an area that may be impacted by a proposed flood control project.

Resistance / resistivity results showing unban industrial archaeological features

Because of the very uniform geologic background within the survey area, even very subtle, low contrast cultural features appeared strikingly in the geophysical data. The survey was successful in identifying a number of cultural features of historic origin, some of which may be associated with a 19th Century brewery complex. Building foundations, utility lines, and a city street were apparent in the resistance data. Although the sources of these anomalies are shallowly buried (less than 1 meter in depth) and evidently retain some some integrity, they are not expressed on the surface.

The survey also identified several resistance anomalies which may be of Native American origin. Subsurface testing of these anomalies has not yet been performed, but other investigations suggest that there may have been a Native American occupation in the vicinity. Interpretations are overlaid on the geophysical data on the smaller map.

resistance / resistivity results with interpretations  

Geophysical anomalies traced in yellow are thought to represent late 19th and early 20th century features associated with the Jacob Dobmeier Brewery complex and the former city street on which it was located. The outlines of 3rd street and associated utility lines are plainly visible. A rectangular "grid" of linear resistance highs at 50 N, 135 E may be associated with the refrigeration equipment belonging to the brewery's ice house.

Those features traced in blue are thought to be "modern" 20th century features related to the sites present use as an urban park.

Geophysical anomalous regions traced in red are possibly cultural features, but of an indeterminate origin. Included in this category are two rectangular anomalies, located at 95 N, 150 E and 80 N, 160 E, both of which may be historic building foundations

Features traced in green may represent prehistoric or proto-historic Native American cultural features. Soil coring data collected prior to the geophysical survey suggests that there may have been a Native American occupation within the survey area.

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