North American Database of Archaeological Geophysics
North American Database of Archaeological Geophysics
Abstract/Summary:
Project Name: Fort Clark Trading Post (32ME2), ND;
Reference: Kvamme, K.L. (2001). Interim Report of Geophysical Investigations at the Fort Clark and Primeau's Trading Posts, Fort Clark State Historic Site (32ME2): 2000 Investigations. ArcheoImaging Lab, Department of Anthropology and Center for Advanced Spatial Technologies, University of Arkansas, Fayetteville, Arkansas. Submitted to PaleoCultural Research Group, Flagstaff, Arizona, and State Historical Society of North Dakota, Bismarck, North Dakota.
Ahler, S.A., Kvamme, K.L, and J.C. Kvamme (2000) Summary Report on 2000 Field Investigations at Fort Clark State Historic Site, 32ME2, Mercer County, North Dakota. ArcheoImaging Lab, Department of Anthropology and Center for Advanced Spatial Technologies, University of Arkansas, Fayetteville, Arkansas. Submitted to the State Historical Society of North Dakota, Bismarck, North Dakota.
The Fort Clark Trading Post was named after William Clark of the Lewis and Clark expedition. It is located in central North Dakota and was one of several important trading centers on the upper Missouri River. Founded by the American Fur Company and supplied by steamboats from St. Louis, it was sited about 200 m south of the the Mandan village of Mit-tutta-hang-kush in 1830 or 1831. Many first-hand written accounts exist about this site. Its visitors included Prince Maximilian of Wied, and the artists Catlin and Bodmer who left depictions of this trading post in paintings. The magnetic survey results include three principal zones of interest. First, the outlines of the centrally placed trading post are apparent, with a number of walls and rooms clearly visible. Fort Clark was burned in 1860 and, although its remains were used as a fuel source for steamboat traffic, the firing may have left some of the large magnetic signatures seen. A small amount of rubble on the site indicates, however, that foundation stones were composed of a magnetic sandstone and numerous iron artifacts undoubtedly litter the area, contributing to the signal. Although the Missouri River presently flows about a mile from the site, during the 19th century it flowed adjacent to the bluff edge to the east. A Euroamerican cemetery, located on the high bluff edge immediately across a draw from the trading post, illustrates a number of graves suggested by the data, only some of which are visible as depressions in the surface.
The magnetic data also illustrate Garreau's lodge and enclosure. Garreau was a full-blooded Arikara who took the name of his step-father, an employee of the trading post. The locus of this circular, earth-covered lodge is readily seen, as is its entryway to the east, central hearth, a number of probable sub-floor cache pits, and a plethora of iron artifacts. Also visible is a faint suggestion of the surrounding enclosure.
The magnetic susceptibility (MS) survey utilized the in-phase component of data logged with the EM-38B. Unlike the magnetic gradiometry survey, which utilized a passive technique, the MS survey employed an active method that injected a signal into the earth and measured subsurface responses to the signal. While the MS data parallel the magnetic findings many new details and subtle features are also revealed, including better definition of a number of likely rooms, room blocks, and other features.
The electrical resistivity data perhaps more clearly reveal some of the individual walls of the trading post, with multiple rooms suggested. Confusing the picture, however, are a number of linear trenches excavated throughout the site by archaeologists in the 1970s. Nevertheless, the data compare well with extant historical maps, including a sketch prepared by Prince Maximilian in 1833-4.
Electromagnetic (EM) conductivity data were acquired by using the out-of-phase (or quadrature) component of the data logged with the EM-38B. These data were obtained simultaneously with the magnetic susceptibility data. While soil resistivity and conductivity are the theoretical inverse of each other, the results of these surveys include important differences stemming from the very different instrumentation employed to obtain each data set and variations in the soil volumes evaluated.
A small section of Fort Clark was surveyed by GPR in 40 transects, each 30 m long focused on a portion of the fort's perimeter room blocks. Interpolation methods were then employed to generate a time slice between the profiles at 10-15 nS (TWTT). Clearly visible are the principal alignments of some of the trading post's walls, but only a subset are revealed in comparison with the resistivity survey findings.
The community of Mit-tutta-hang-kush was occupied by the Mitutanika Mandan from the summer of 1822 until 1837, the year of a disastrous smallpox epidemic. The site is located on a high terrace above the Missouri River, which provided good defense on two sides of the village from attacks by native enemies. The remaining village perimeter was protected by a palisade. The Fort Clark Trading Post and Primeau's Trading Post were located adjacent to this village. Many first-hand written accounts exist about this site. Its visitors included Prince Maximilian of Wied, and the artists Catlin and Bodmer who left depictions of the village and its occupants in paintings. In June of 1837 the steamboat St. Peters arrived at Fort Clark carrying three Arikara women recovering from smallpox. By July the disease broke out in the village. At the epidemic's height, in August, the survivors moved to their winter village ahead of schedule. Before they returned to Mit-tutta-hang-kush the following spring, it was occupied by their rivals, the Arikara, who continued occupying this site until 1860. It is estimated that the smallpox epidemic reduced the approximately 1,600 Mandan to about 125. Today this large site, measuring nearly 400 x 300 m, exhibits numerous "house" depressions" in the landscape indicating the loci of the former earthlodges of the Mandan and Arikara. Some of of these topographic features can be seen in aerial photographs.
The magnetic survey represents a transect 400 m long by 20 m wide through the center of this site. Many of the circular earthlodges, about 15-20 m in diameter, are indicated, as are some of their internal features like centrally placed and auxiliary hearths, storage pits, and internal support posts. Also revealed is a portion of the perimeter fortification ditch and the village plaza of the Mandan. The presence of numerous iron artifacts is indicated by a large number of dipole anomalies; it is clear that some lodges possessed many more iron artifacts than others, perhaps indicating greater associations with the nearby trading posts.
The resistance survey covers much the same area as the magnetic survey. Many of the earthlodges are clearly indicated, paralleling and augmenting the magnetic evidence. Importantly, there is at least one instance of overlapping lodges which may indicate the placement of a later Arikara house over an earlier Mandan lodge. A trail feature, known to lead to a nearby contemporary village, also is revealed. The expression of a large Arikara ceremonial lodge is particularly clear, including some of its internal features like the central hearth.