Case Study
Songbird Rings
Big Horn County, Montana
Songbird Rings (24BH1162) is a prehistoric archaeological
site in southeastern Montana. The "rings" referred to
in the name of the site are stone rings (also called stone circles
or tipi rings), a type of archaeological feature characteristic
of prehistoric campsites on the Great Plains. Composed of natural
stones arranged in a circular pattern, they are usually interpreted
as having weighted down the edges of tipis or other types of circular
tents (although there are exceptions where this seems unlikely).
Where the rock that comprises the stone ring is of
igneous origin, it may be detectable by magnetometer survey, allowing
these features to be mapped even where they are not exposed. Even
when partially exposed, circular patterning may not be readily apparent,
and magnetic mapping can be valuable in distinguishing cultural
from natural distributions of stones. Sedimentary rocks are generally
more difficult to detect by magnetic methods, although in the case
of Songbird Rings, the stone rings were composed of scoria - sedimentary
rock thermally altered by burning coal seams, rendering it highly
magnetic.
A magnetic gradiometer was used to survey several areas
within the Songbird Rings site. The results from one of these survey
areas are shown below. At this time, preliminary testing has largely
confirmed magnetic survey interpretations, but the site has not
been excavated or extensively tested.
Mouse over image to display interpretations
- Two stone rings are readily apparent as roughly circular patterns
of bipolar anomalies. The positive and negative components of
these anomalies represent the poles of the magnetic fields of
individual rocks within the ring.
- Four anomalies are present (circled in yellow) that have been
confirmed by subsurface testing as prehistoric hearths. Hearth
features are often detectable magnetically, typically appearing
as moderately strong circular magnetic highs (although other expressions
are also seen).
- Several anomalies circled in black are suspected as prehistoric
features, but have either not been tested, or initial testing
results have been inconclusive.
Geophysical survey of the Songbird Rings site was performed by
Archaeo-Physics as part of an archaeological investigation under
the direction of Gene Munson of GCM Services, Inc. The project was
commissioned by Westmoreland Resources, Inc. as part of an assessment
of cultural resources in areas of potential impact by mining.
Related content:
Papers and publications - Geophysical
Survey as an Approach to the Ephemeral Campsite Problem: Case
Studies from the Northern Plains
