Notes on a Donated Collection

Recently, the Historical Society of Saginaw County received a donation of ten flaked stone tools collected from the surface of archaeological site 20SA789. These items supplement a collection of five stone tools from this site previously donated to the museum. For those unfamiliar with the site numbering system used in Michigan, 20 stands for Michigan, SA for Saginaw County, and 789 is the sequential number of sites recorded in the county.

Site 20SA789 is located near the Cass River in Bridgeport Township, Saginaw County, Michigan. It is situated on a terrace adjacent to an intermittent stream and a relict channel of the Cass River at an elevation between ca. 600 and ca. 615 feet (182.9-187.5 meters) above mean sea level (amsl). Given the elevation, at least a portion of the site would have been available for human habitation even during the highest mid-holocene level of the Great Lakes. The Nipissing I lake stage reached an elevation of ca. 605 feet (184.4 m) amsl sometime between 4500 and 4800 BP (Monaghan and Lovis 2005).

Note: BP, or B. P., stands for Before Present. By convention, “present” is considered to be A.D. 1950. Note also that radiocarbon years are not exactly equivalent to calendar years and as you go back in time they become progressively too young. For example, 4000 radiocarbon years BP is roughly equivalent to 2500 B.C. and 5000 radiocarbon years BP is roughly equivalent to 3700 B.C. For this reason, radiocarbon years need to be calibrated to match “calendar years” and a variety of calibration curves have been devised to do just that. Uncalibrated dates are often presented using the lower case b.p.

The recent donation, pictured here, includes six bifacial projectile points/knives (A-F), three unifacially retouched flakes (G-I), and a bipolar core (J). Only the projectile points/knives are temporally diagnostic.

20SA789 artifacts

Artifact A, in the above photo, is made of Bayport chert. Although the base is damaged, it appears to be one of the Early Archaic bifurcate types. This assessment is based on the overall shape of the blade and the flattened lenticular cross-section. Unfortunately the base, much of which is missing in this example, is the diagnostic element of bifurcates so this determination must remain tentative. If it is indeed a bifurcate it likely fits in with the LeCroy, Lake Erie and Kanawha Stemmed group, thus dating to around 8500-7800 BP (Justice 1987). With a dearth of radiocarbon dates from sites/components yielding bifurcate points in Michigan these dates are necessarily based on similar-looking material from other states. One of the blade edges of this specimen (left edge in the photo) exhibits moderate grinding/usewear, perhaps indicating use as a knife on a hard surface.

Artifacts B and C are Raddatz-like points diagnostic of the Middle Archaic (ca. 6200-4500 BP) Dehmel Road Phase (Lovis 1989). They are made of Bayport chert (B) and Norwood chert (C). The pinkish color of the Norwood chert example likely indicates the stone was heat-treated to enhance its knapping properties. The Dehmel Road Phase was defined on the basis of material excavated at the Weber I site (20SA581) located less than 10 km (6 miles) upstream along the Cass River. A Raddatz-like point was also recovered from Stratum 4 at the Bear Creek site (20SA1043), which has been dated to ca. 4250 BP (Branstner and Hambacher 1994). The Bear Creek occupation may mark the transition from the Middle Archaic Dehmel Road Phase into the Late Archaic period. Similar large side-notched points with heavily ground bases have been found in small numbers at many sites in the Saginaw Valley.

Specimens D-F are examples of corner-notched Feeheley or Brewerton-like points. There is some ambiguity about the temporal placement of this type in Michigan. Similar broad-bladed, corner to side-notched points assigned to the Feeheley or Brewerton constructs in Michigan encompass a great deal of morphological variability and seem to span much of the Late Archaic period from ca. 5000 BP to 3600 BP (Justice 1987). To further complicate matters, certain corner-notched Middle Woodland points may be nearly indistinguishable from Late Archaic specimens (Lovis and Robertson 1989:233).

Specimens G-I are unifacially retouched flakes/scrapers. Each is made of Bayport chert. The final artifact in this collection, specimen J, is a bipolar core or wedge (sometimes referred to with the term piece esquillee). This specimen is likewise made of Bayport chert. These items are not diagnostic of any particular time period, but are not uncommon on Middle or Late Archaic period sites.

This newly donated material is a welcome addition to our extant collection from 20SA789. None of the five stone tools already present in the museum’s collection from this site is diagnostic. These items, pictured below, consist of a unifacially retouched flake/scraper and four bifacial implements.

20SA789 acc 27

Specimen A in this photo is a unifacially retouched flake, likely used as a scraping or cutting tool. Edge retouch is present on the dorsal surface of the top, bottom and left edge and on the ventral surface along the right edge (as oriented in the photo). This tool is made on a Bayport chert flake.

Specimen B is a bifacial tool that closely resembles certain “end scrapers” frequently found in terminal Archaic Meadowood assemblages. The rounded point of this artifact is actually the ground striking platform of the flake from which this biface was manufactured. The raw material is an unidentified, banded chert (possibly a pebble chert). It appears to have been heat-treated.

Artifacts C and E respectively are stage 2 and 3 bifaces made of Bayport chert. These represent stages along the continuum of an artifact manufacturing process that starts with a core or flake “blank” and ends with the finished tool.

Artifact D is a well-made biface with a constricted, parallel-sided (and snapped off) blade that likely served as a drill. The edges of the constricted blade exhibit heavy usewear/grinding. The yellowish-orange patina of the Bayport chert and the semi-collateral flaking pattern hint that this may be an early (Early Archaic?) piece. However, neither trait is definitive.

It is only because we have the crucial provenience information that this assemblage of artifacts from 20SA789 is an important piece of Saginaw’s archaeological record. Without this information, these objects would be little more than curiosities, or pretty stones. Diagnostic artifacts among the recently donated specimens span much of the Archaic Period. As we continue to refine our knowledge of the local Archaic chronology collections such as this will become even more important markers of the changing distribution of people across the landscape through time. The Historical Society of Saginaw County is grateful that these items were preserved and entrusted to our care.

More information and examples of Archaic Period artifacts can be found here on the Castle Museum website and in the Museum’s archaeology exhibit Revealing our Buried Past: Archaeology of the Saginaw Valley. Sources cited in this post are listed on the References page of this blog.



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