

Type of survey: Magnetic gradiometry; Instrument: Geoscan Research FM-36 fluxgate gradiometer; Prospection depth: up to 1.5 m; Sampling interval: 0.5 x 0.125 m; Area surveyed: 7,100 m2; Dates of survey: 7/99.
Comments: Huff village is a spectacular fortified village
located on the Missouri River in south-central North Dakota. The site
covers about 3.4 ha, exhibits at least 103 depressions on the surface
indicating the locations of rectangular houses, a fortification system
with ditch, palisade, and 10 bastion loops, and a large ceremonial lodge
near the central village plaza. Huff is know for its spatial organization
where orderly rows of houses parallel each other across the site.
Salvage work was conducted at Huff
in the 1960s by W.R. Wood who recognized it as an ancestral Mandan village.
Many of the above features and some of Wood's open excavations are
revealed in an aerial photograph from that time (first figure). Also depicted
in that photo, superimposed, are the results of the magnetic survey (in blue)
with 20 m grids indicated.
The magnetic survey of Huff (second figure, above) has provided a new perspective
on fortified village sites on the Missouri. About 85% of the more than 400
magnetic anomalies represent storage features (as indicated by an excavation
and coring program), an unexpectedly high number. Even more noteworthy is
their distribution, for the most part outside of the known houses
(as indicated by the surface depressions), a fact not previously realized owing
to a concentration of archaeological work within houses. With a typical depth
of 1.5 m and a diameter of 1.0 m (see photo to right), a considerable storage capacity is suggested
when projected to the entire village, testifying to the volume of horticultural
production. These magnetic data also clearly shown an absence of
ground-disturbing activity of any kind within the central village plaza area
(top of survey grid), pointing to another aspect of village organization.
A comparison of houses excavated by Wood with the magnetic data (third figure, above)
reveals commonalities in size, orientation, and in feature distributions,
with indications of centrally
placed hearths, laterally placed auxiliary hearths, interior storage features,
and entranceways.
Comparison with an historic magnetic data set. One house at Huff Village,
known as House 19, was magnetically surveyed by Nickel and Weymouth in 1977
using the older technology of a proton precession magnetometer and a 1 m
sampling interval. GIS methods were employed to register the data to our 1999
survey allowing comparison with our magnetic data (with 8 measurements/m2
). A side-by-side comparison (figure) reveals nearly identical
findings with all principal anomalies indicated, pointing to the relative
constancy of magnetic phenomena.
Type of survey: Resistivity; Instrument: Geoscan Research RM-15; Prospection depth: 1.5 m; Sampling interval: 0.5 x 0.5 m; Area surveyed: 1,600 m2; Dates of survey: 7/99.
Comments: The electrical resistivity survey at a 1.5 m probe spacing
(depth) was based on findings obtained in a six multi-depth resistivity
study (see below), where the 1.5 m depth was shown to most clearly portray
house form. The limited study area investigated clearly reveals four
rectangular houses as high resistivity features (shown in blue).
Interior features were not indicated at this prospection depth. Many of
the point anomalies merely reflect rodent burrows.
Type of survey: Resistivity tomography; Instrument: Geoscan Research RM-15 / MPX-15; Prospection depths: 0.25, 0.5, 0.75, 1.0, 1.25, 1.5 m; Sampling interval: 0.5 x 0.5 m; Area surveyed: 400 m2; Dates of survey: 7/99.
Comments: This survey was centered about the House 19 surface depression.
At each "depth" of survey a 40 x 40 matrix of resistance measurements was
obtained; with 6 depths a data volume was created. Computer processing
techniques were employed to literally "slice" the data cube along various axes
to investigate patters of resistivity (left figure). At shallow depths the data
indicate low resistivity (blue) within House 19, which is surrounded by
high resistivity measurements (red). The house floors (about 30-40 cm below
surface) at Huff are known to be compacted, probably serving as effective moisture
barriers. With the basin-shaped microtopography above them serving to concentrate
rainfall, the result is a concentration of moisture above the floor that lowers
the apparent resistivity. The surrounding
berm of elevated ground surrounding each house depression causes the reverse
to occur by decreasing ground moisture and raising apparent resistivity. At the
same time the compacted floors also serve to inhibit moisture penetration below
the floors causing a marked increase in resistivity at larger depths, and an
interesting resistivity reversal, revealed in both cross-sections in the
left figure, and dynamically in the animation.
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