30 Days of Tennessee Archaeology, Day 22
Ryan M. Parish, PhD and Ellis Durham
University of Tennessee, Memphis
There often exist significant overlapping visual characteristics both within and between chert sources. This fact coupled with our propensity to identify raw materials as exotic potentially causes misidentifications of prehistoric stone artifacts. In turn, the identification or misidentification of chert artifacts leads to conclusions regarding social networks, mobility, and human behavior that may be unsound. Knife River Flint (KRF) was a widely utilized and circulated tool stone in the northern Great Plains throughout the entire prehistoric record. It is a common material type found in artifact assemblages throughout North Dakota and into Canada. KRF is also a material type identified on sites in Maine and Florida and just about every state in between. In Tennessee, KRF is rarely but occasionally identified usually as projectile points and other curated artifacts. Are these artifacts really made from KRF, the source of which is located over 2,000 km (1,400 miles) away?
Visually, KRF is said to be pretty distinctive, a translucent fine grained amber, root beer, beer bottle glass colored material sometimes with small white fossil inclusions.
However, researchers in the source region identify visually similar varieties of chert, chalcedony, petrified wood, and silicified peat. The main prehistoric procurement sites of KRF occur in Dunn and Mercer County, ND as secondary gravel deposits thought to belong to the glaciated/eroded Golden Valley Formation. Glacial and alluvial deposits of KRF extend southeastward from Montana to Iowa. The historically documented Hidatsa and Mandan tribes maintained a broad trade network within which KRF was exported although the true extent of which has yet to be confirmed using analytical techniques in most regions.
As Barbara Luedtke used to assert, ‘assume a local source first’, we must be critical of KRF claims in Tennessee. What, if any chert sources in Tennessee or vicinity could be similar in description? First, before we speculate on possible local look-a-likes let’s briefly recap major toolstone sources in Tennessee. The Central Basin (Nashville) contains older Silurian and Ordovician carbonate sources such as Brassfield (waxy, green/blue/gray/orange) and Bigby Cannon (fine grained, laminated brown/black). Camden chert, Devonian in age, occurs just west of the Central Basin and provides a medium grained white chert with opaque inclusions. The Western and Eastern Highland Rim contains abundant Mississippian epoch aged Fort Payne (coarse to fine grained white/tan/mottled brown/dark gray), Warsaw (fossiliferous blue/gray), St. Louis (waxy, green/blue/gray), and Ste. Genevieve/Monteagle (waxy, blue, gray) sources. Cretaceous gravels; Horse Creek (medium grained tan/red/yellow/gray) exist along the Tennessee River at the edge of the Highland Rim and Coastal Plain of southern Tennessee, northeastern Mississippi, and northwestern Alabama. The Coastal Plain in western Tennessee is dominated by Pliocene Upland Complex gravel (medium grained tan/brown) sources. Finally, the Valley and Ridge of eastern Tennessee has Ordovician sources such as Knox chert (fine grained translucent black/blue) and quartzite (medium grained white/tan).
Though the authors do not claim to have conducted an exhaustive survey of tool stone sources, a fair amount of time visiting, surveying, and sampling various sources allows us to offer up a speculation of local KRF look-a-likes. The extensive and diverse gravel deposits within and along the Mississippi River contain chert that certainly provided prehistoric people with a wide selection of materials. However, we have never observed chert gravels that are fine grained/waxy or translucent. The multi-colored Cretaceous gravels at the northern inflection point of the Tennessee River likewise do not contain material similar to KRF. Neither do the Valley and Ridge sources appear to provide a visual match for KRF despite the range of white/opaque/blue/black translucent varieties present. A match has not currently been observed in the Ordovician, Silurian, and Devonian chert sources of the Central Basin and vicinity.
That leaves the Mississippian aged sources of the Highland Rim, varieties of which overlap visually with KRF. Specifically, the upper Fort Payne and lower Warsaw occasionally produces a root beer translucent chert with white fossil inclusions. Also, both the Upper St. Louis and Ste. Genevieve/Monteagle sources are waxy and occasionally occur as tan/dark brown materials. Some would refer to these varieties as a chalcedony. I would shy away from the use of the term chalcedony, as the KRF look-a-like materials do not appear to be dominated by a fibrous quartz crystalline structure.
The take away theme is this; that the many varieties of cherts that prehistoric people selected and used may sometimes have significant overlapping visual characteristics. This fact makes identification of exotic material from long distances away appealing but potentially flawed. The 240 lbs. of KRF collected from nine sources in North Dakota this summer may help us for the first time confirm or deny the presence of KRF in Tennessee using reflectance spectroscopy.
*Answer – KRF is the top sample. The bottom two are probably a St. Louis chert variety.