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Brooke Morgan's blog

Archaeology is Elemental: Geochemical Source Analysis of Obsidian Artifacts from North Dakota

Lithics, or stone tools and flaking debris, are among the most common artifacts found at archaeological sites in North Dakota. They can convey information to archaeologists about the people who made these objects, and they can also tell a much larger story of landscape use and cultural interaction. The rocks people eventually knapped into tools had to first be collected—sometimes this was done directly by the knappers themselves, and sometimes stone was acquired through trade with other groups of people. Lithic materials from North Dakota sites come from a vast area that includes the Northern Plains, Upper Great Lakes, and Rocky Mountains. Obsidian artifacts are occasionally found in North Dakota, but there are no obsidian sources within the state. Obsidian was prized by knappers for its properties. It is a high-quality, reliable stone with hardly any flaws, and it produces very sharp edges. It may have also been favored for its aesthetic value.

Map of regional lithic raw material sources

Regional lithic raw material sources. (State Historical Society of North Dakota)

Obsidian forms during volcanic eruptions when lava flows supercool upon contact with air or water, creating volcanic glass. Each volcanic flow has a distinct geologic and chemical signature, and the chemical composition of the obsidian formed from these flows is uniform throughout the source. Obsidian is composed mainly of silica (which gives it its glass-like appearance), but also contains trace elements such as zirconium, niobium, iron, and manganese. The ratios of these trace elements differ between obsidian sources, distinguishing them from each other on an elemental scale. Archaeologists specializing in geochemical techniques use instruments to analyze geological samples and determine a trace element profile for that source. Think of a trace element profile as a kind of fingerprint—although obsidian sources may be similar, no two are exactly alike. Once a geochemist has a fingerprint of the geologic source, it can be compared with artifacts made from obsidian. One of the most common instruments used to assess trace element composition is an energy dispersive x-ray fluorescence spectrometer (EDXRF). This analysis is non-destructive, which makes it especially useful for testing museum specimens.

Obsidian artifacts

Obsidian artifacts sent for sourcing (left to right: projectile point from Beadmaker; biface from Huff; biface from Shermer). (State Historical Society of North Dakota)

Previous research has shown that North Dakota knappers used obsidian from three main sources in the Yellowstone region: Obsidian Cliff (Wyoming), Bear Gulch (Idaho), and Malad (Idaho)1. This earlier study did not include artifacts from Mandan villages, and we were curious about trade patterns at these sites. The Mandans were key players in an expansive Northern Plains trade network during the Plains Village period, and certain villages may have controlled access to obsidian materials. Obsidian tools and flakes were selected from six Mandan villages and one Mandan campsite that date between AD 1300 and AD 1750. These 76 samples were analyzed by Richard Hughes, Ph.D., at the Geochemical Research Laboratory in Portola Valley, California.

Wyoming obsidian sources

Wyoming obsidian sources (courtesy Northwest Research Obsidian Studies Laboratory, www.obsidianlab.com)

Idaho obsidian sources

Idaho obsidian sources (courtesy Northwest Research Obsidian Studies Laboratory, www.obsidianlab.com)

Using EDXRF, Dr. Hughes concluded the obsidian artifacts from the Mandan sites came from the Obsidian Cliff and Bear Gulch sources. No artifacts were sourced to Malad. All sites but one had a combination of Obsidian Cliff and Bear Gulch artifacts, although in differing frequencies. The outlier was Huff, but only one artifact was submitted, and this was sourced to Obsidian Cliff.

What does this mean for patterns of exchange in the Mandan world? While this is a pilot study—that is, the first step of a larger project—we can hypothesize that use of Obsidian Cliff versus Bear Gulch materials at Mandan sites was not controlled by certain Mandan villages. Instead, obsidian imports into this region of North Dakota were more likely driven by the hunter-gatherers that controlled access to obsidian outcrops in the Yellowstone area. An expanded sample of Mandan obsidian artifacts will help refine our understanding of regional trade networks.


1 Baugh, Timothy G. and Fred W. Nelson (1988) Archaeological Obsidian Recovered from Selected North Dakota Sites and Its Relationship to Changing Exchange Systems in the Plains. Journal of the North Dakota Archaeological Association 3:74-94.

A Century of Mapping at Huff Indian Village State Historic Site: How Archaeology Changes Over Time

Archaeologists have a solid understanding of Mandan lifeways at Huff Indian Village State Historic Site, primarily as a result of extensive excavations in 1960 as part of the Smithsonian Institution River Basin Surveys1 and additional geophysical and archaeological testing in 19992. But Huff Village was known to archaeologists prior to this time—in fact, it was first recorded as early as 1904 by Ernst R. Steinbrueck, who worked as a field officer for the State Historical Society. Under the direction of Orin G. Libby, Steinbrueck created a list of sites and produced location maps for villages along the Missouri River. One such map in the archaeology collections is dated December 22, 1906, and titled “Map showing approximate location of the ancient Indian village sites found since 1902” (Figure 1). Some familiar sites appear on this map. On the east side of the river, Double Ditch (No. 40) is visible. Fort Lincoln (No. 2) can be seen on the west side of the river. What we now call “Huff Village” was known by Steinbrueck and his contemporaries as “Arikara Fort,” and is No. 19 on this map.

Map of Missouri River villages - 1906

E.R. Steinbrueck’s 1906 map of Missouri River villages. (State Historical Society of North Dakota, Archaeology and Historic Preservation Division flat files)

Archaeological knowledge changes over time, and in Steinbrueck’s era, archaeologists thought they had identified an Arikara village enclosed by a fortification wall—hence, Arikara Fort. We’ve known for some time that Huff is in fact a Mandan village, based on ceramics and other artifacts. But that isn’t the only thing that has changed: in 1908, Steinbrueck drew a map of “Arikara Fort” with 182 lodges inside the fortification ditch (Figure 2). Eleven of the houses are rectangular, and the rest are circular. Compare that map with one drawn by archaeologist W. Raymond Wood in 1960 (Figure 3). This map shows 102 houses, 101 of which are rectangular. On Wood’s map, there is only one square lodge with rounded corners, which could be interpreted as a circular lodge.

Map of Arikara Fort

E.R. Steinbrueck’s 1908 map of “Arikara Fort.” (State Historical Society of North Dakota, Archaeology and Historic Preservation Division flat files)

Map of Huff Village

W. Raymond Wood’s 1960 map of Huff Village. (Wood 1967: Map 4)

Wood assembled published and unpublished maps of Huff Village to show the variations in village interpretation over time (Figure 4). We now know that among the Mandan, long-rectangular houses preceded round earthlodges. This is evident at Huff, which dates to about AD 1450: the single round lodge shows that people were experimenting with a new form of housing.

Comparative maps of Huff Village

W. Raymond Wood’s comparative maps of Huff Village, 1905-1960. (Wood 1967: Map 3)

So why did early maps of Huff Village show circular lodges? Wood (1967:28) offers the following explanation:

This resume of the history of Huff cartography is particularly interesting in revealing the extent to which preconceptions effect the perception of field data. The first long-rectangular house excavated in North Dakota was House 5 at Huff, dug by Thad. Hecker in 1938-39. Prior to that time there was no hint in the literature of villages composed solely of long-rectangular houses. The local historic earth lodges were circular and, despite the large number of sites available of long-rectangular houses, field workers persisted in “seeing” the circular houses they expected to find.

In other words, people were familiar with the round earthlodges used historically by Mandan Indians and anticipated finding evidence of similar lodges in the archaeological record. This is a form of confirmation bias, or finding results that uphold your existing beliefs. It’s something that archaeologists—and all scientists—must be aware of in their research. The variation in the number of recorded lodges suggests some of the earliest drawings were impressionistic and not created using survey equipment. Improvement in mapping technology has allowed for extensive geophysical survey (including magnetic and electrical resistance surveys) to be performed at Huff. This helps archaeologists “see” underground and pinpoint individual features for excavation (Figure 5).

Comparison of house plans

Comparison of (a) house plans drafted by Wood (1967) and (b) houses identified by magnetic survey. (Ahler and Kvamme 2000: Figure 18)

So what comes next in this second century of research at Huff? Researchers from the University of Texas at Dallas Geospatial Analytics and Innovative Applications Research Lab are using drone technology to take aerial photographs that can be georeferenced down to a centimeter. This precise form of mapping will improve our perception of microtopography (or small landscape features), as well as provide state-of-the-art figures for publication and outreach. There’s still much to learn from this exceptionally-preserved site. Take some time to visit Huff this fall, and observe the lodges and fortification ditch yourself.


1 Wood, W. Raymond. 1967. An Interpretation of Mandan Culture History. River Basin Surveys Papers 39. Smithsonian Institution, Bureau of American Ethnology Bulletin 198. Washington, D.C.
2 Ahler, Stanley A., and Kenneth L. Kvamme. 2000. New Geophysical Research and Archaeological Investigations at Huff Village State Historic Site (32MO11), Morton County, North Dakota. Research Contribution 26. PaleoCultural Research Group, Flagstaff, AZ. Submitted to the State Historical Society of North Dakota, Bismarck.