Geophysical Investigations and Monitoring of Selected Areas Associated with the Dry Prairie Rural Water System Tie-In Construction Project at Fort Union Trading Post National Historic Site, Roosevelt County, Montana, and Williams County, North Dakota

Summary

The National Park Service’s Midwest Archeological Center and Fort Union Trading Post National Historic Site staffs conducted geophysical investigations and construction project monitoring at the Fort Union Trading National Historic Site in Roosevelt County, Montana, and Williams County, North Dakota. The geophysical and archeological investigations were conducted between October 30 and November 16, 2007. The archeological investigations were requested by the park staff for selected areas within the park along the installation route of the Dry Prairie rural water system tie-in with the park’s existing water system in Roosevelt County, Montana, and Williams County, North Dakota. The project location extends across the southern portion of the Mondak townsite, the open prairie between the Mondak townsite and the Fort Union Trading Post site, the open prairie between the Fort Union Trading Post site and the park well near the Garden Coulee site, and the Garden Coulee site to the park’s maintenance facility and the well house.

During the investigations, 8,400 square meters or 2.08 acres were surveyed with a fluxgate gradiometer. The magnetic data collected at the selected project areas provided information of the physical properties (magnetic) of the subsurface materials. Several scale magnetic anomalies were identified. During the trenching activities associated with the waterline installation, two anomalies were excavated in Grid Area 5 and Grid Area 2. The feature (Feature 1 within the boundary of Site 32WI17) identified in Grid Area 5 was a small trash filled basin dating to the trading post occupation period between 1829 and 1867. The small charcoal filled pit (Feature 3 within the boundary of Site 32WI17) in Grid Area 2 was also associated with the occupation of the trading post in the mid 1800s. The third feature, found next to the well house during the monitoring of the trench for the installation of waterline hardware (valves), contained materials that dated to the late 1800s and early 1900s. The site was documented and recorded as Site 32WI996. This large trash dump feature may have been associated with the trading post, the Crow-Flies-High village site above Garden Coulee, and the 20th century community of Mondak. It is also possible that the feature represented the disposal of debris from the late 1800s and 1900s agricultural field activities. The presence of numerous magnetic anomalies along the west side of Grid Area 5 suggested the presence of buried materials associated with the occupation of the trading post. It is recommended that additional archeological investigations be undertaken should the park staff decide to construct a fire-suppression vehicle access and parking pad in this area. Due to the successful nature of the magnetic survey, it is also recommended that the park staff develop a plan for the complete magnetic survey of the unsurveyed portions of the park.

This Resource is Part of the Following Collections

• CRM Archaeology and tDAR   •
• Midwest Archeological Center Technical Reports

Keywords

Spatial Coverage

Individual & Institutional Roles

Contributor(s): Kenneth P. Cannon

Repository(s): Midwest Archeological Center

Record Identifiers

MWAC Accession Number(s): 1197

File Information