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Knife River Flint (KRF) (North Dakota)

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  • Knife River Flint (KRF) (North Dakota)

    Knife River Flint (KRF)

    Artifacts made of this northern High Plains material are highly sought after because of the aesthetic qualities they exhibit. The following information is a brief description of KRF and its source.

    The generally accepted source of Knife River Flint is in Dunn County in western North Dakota. KRF is an exceptionally high-quality and durable toolstone. It has a wide distribution range throughout the states and provinces adjacent to and even farther removed from its source in North Dakota. It is distinctive in appearance, and identification based on general appearance is usually considered unequivocal (Frison 1982).

    KRF is silicified lignite and is a finely textured, uniform, nonporous, brown to dark brown, translucent chert (flint) with excellent flaking qualities. It occurs in secondary deposits in the form of subangular, tabular, and blocky pieces that can range in size from gravel to small boulders.

    The presence of white fossil plant fragments in the brown translucent flint help distinguish it from other look-alike materials such as Scenic chalcedony and others sources from the White River group silicates found in western South Dakota and northwestern Nebraska. Ultraviolet (UV) fluorescence can be useful in distinguishing KRF from the similar look-alike materials.

    Patination of KRF artifacts can vary from absent to a very intense cream-white patina. Patination is caused by dissolution of silica from the surface of the artifact and the patina is almost always the most intense on the upper facing surface of a buried artifact. Variables important to the amount of patination include time, pH, moisture, and temperature and will vary greatly from one region to another. However, lack of patination is not an indicator of age as unpatinated artifacts may date from the Paleoindian through Late Prehistoric periods (Root et al. 1986). The majority of the KRF artifacts that I have seen or found from south central Nebraska have a near absence of white patina due to the neutral soils but oftentimes they exhibit a very light lustrous haze or a light bluish surface haze.

    Because KRF is such a high quality lithic it is not unusual to find artifacts made from it at great distances from its source. This is especially true of artifacts made by Paleoindian cultures. These early cultures were very mobile and long distance transport of high quality lithics was not an uncommon practice. A number of Paleoindian artifacts made of KRF have been found in southern Nebraska at an approximate distance of 500 miles from the lithic source.

    The artifacts in the images are examples from southern Nebraska. It can be a challenge to photograph KRF on a black background, therefore those images have had the background Photoshoped. The image of the backlit Pelican Lake point is a good example showing the fossil plant fibers however not all KRF artifacts will have these fossil inclusions.

    The last image is a natural (unmodified) piece of tabular nodule of KRF with an orangish colored cortex covering much of its surface.

    Map showing source location and the general distribution of KRF in the Great Plains region compliments of Jeb Taylor. KRF artifacts are found beyond the boundaries of this map, especially such as those found on Hopewell sites in the Midwest.

    Prehistoric Hunters of the High Plains (G.C. Frison, 1978)
    Projectile Points of the High Plains (Jeb Taylor, 2006)
    The Archaeology of the Bobtail Wolf Site (M.J. Root, 2000)

  • #2
    Example from S. Iowa.


    • #3
      From North Dakota

      Photo courtesy of Ron Kelley
      Searching the fields of NW Indiana and SW Michigan


      • #4
        From South Dakota Click image for larger version

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        South Dakota


        • #5
          Here is a Pelican lake point made from Knife River Flint, that is heavily patinated. You can see a tiny bit of the lithic sticking out on the shoulder. Click image for larger version  Name:	003.JPG Views:	2 Size:	131.8 KB ID:	241055

          South Dakota