Archaeological Geophysics
Silvernale Site, MN       

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In 2002, Ron Schirmer, Don Johnson, and Clark Dobbs led the first investigation at Silvernale in 25 years.  This investigation included shovel testing, geophysical surveying (magnetics and resistance), and combining existing maps and air photos to determine site boundaries and patterning within the site.  A summary of this project is provided in this web site on the Publications page.

The most significant conclusions of the subsurface examinations in 2002 were that intact archaeological deposits are abundant at the site and that they are substantially below the surfaces disturbed by cultivation.  Therefore, Minnesota State University - Mankato chose Silvernale as the site for their archaeology field course in 2003, with Ron Schirmer as the PI.

Four areas were excavated during the 2003 field season: two targeted geophysical anomalies, one targeted a feature encountered during shovel testing in 2002, and one investigated the nature of the site buried by the earth berm created by the construction of the railroad in 1882.

Block 1 Resistance

Block 1 consists of three 1-meter excavations units that were dug to investigate a feature encountered during shovel testing.  These units encountered a 15-20 centimeter thick surface midden immediately beneath the plow zone.  Beneath the midden and separated from it by a distinct contact was a pit feature.  The feature contained typical domestic refuse and the pit walls showed evidence of intense heating, thus it may have been an earth oven or maybe a fire pit.  Comparison of excavation results to the resistance data indicates the resistance low west of the excavation block is related to the midden.  The strong resistance low to the northeast is modern fill.

Block 4 Resistance

The target for Block 4 was an oval resistance low.  Excavation revealed a surface midden immediately beneath the plow zone and about 15 to 20 cm thick - similar to the midden encountered at Block 1.  Two features were encountered beneath the midden: a pit containing organic-rich material (resistance low) and a pit containing burned pottery and other burned material (weak resistance high).  The excavations did not extend sufficiently to the north to determine the nature of the linear resistance contact (to be examined in the 2004 field season), but this is interpreted as the edge of the midden.

Midden Map

Reviewing the resistance data along with excavation results leads to the interpretation that an elongated resistance low may be a midden covering an area some 60 meters long and between 10 and 15 meters wide.  Based on excavations, the midden covers earlier features.

Block 4 Resistance

Block 3 consists of three 1-meter excavations targeting a distinctive resistance low.  A house floor was encountered within the southern 2 excavation units while the northern unit was outside the structure.  The floor was somewhat more compacted and organic rich relative to soils from the north unit.  Post molds were noted in the sidewalls of the block between the north and middle units.  Full exposure and investigation of this structure is a primary activity scheduled for the summer of 2004.

Block 2

Construction of the railroad in 1882 required that a trench be dug through the middle of the Silvernale village.  A berm was formed when soil from the trench was dumped on the north side of the railroad tracks.  Excavation Block 2 was positioned to determine the nature of the materials covered by the berm.  Excavations revealed that the berm is composed of a mix of soil containing artifacts.  Immediately beneath the berm, dark organic-rich soil was encountered.  The contact between the berm and the darker soil upon which the berm rests is easily seen in this photo.  The soil beneath the berm shows no evidence of being plowed - that is, it is undisturbed village.  IF this is true and IF the same is true for the remainder of the area covered by the berm, then there is some 5000 sq. meters of undisturbed village through the middle of the site!!