The Cooper’s Ferry site, Idaho, USA; evidence that humans were present in the Americas ~16,000 years ago

This post is a summary of information on the exciting discoveries from the Cooper’s Ferry site in western Idaho, USA.

Stone tools and other artifacts unearthed from an archeological dig at the Cooper’s Ferry site in western Idaho suggest that people lived in the area 16,000 years ago, more than a thousand years earlier than scientists previously thought.

The artifacts would be considered among the earliest evidence of people in North America.

The findings, published in Science, add weight to the hypothesis that initial human migration to the Americas followed a Pacific coastal route rather than through the opening of an inland ice-free corridor, said Loren Davis, a professor of anthropology at Oregon State University and the study’s lead author.

“The Cooper’s Ferry site is located along the Salmon River, which is a tributary of the larger Columbia River basin. Early peoples moving south along the Pacific coast would have encountered the Columbia River as the first place below the glaciers where they could easily walk and paddle in to North America,” Davis said. “Essentially, the Columbia River corridor was the first off-ramp of a Pacific coast migration route.

“The timing and position of the Cooper’s Ferry site is consistent with and most easily explained as the result of an early Pacific coastal migration.”

Cooper’s Ferry, located at the confluence of Rock Creek and the lower Salmon River, is known by the Nez Perce Tribe as an ancient village site named Nipéhe. Today the site is managed by the U.S. Bureau of Land Management.

Davis first began studying Cooper’s Ferry as an archaeologist for the BLM in the 1990s. After joining the Oregon State faculty, he partnered with the BLM to establish a summer archaeological field school there, bringing undergraduate and graduate students from Oregon State and elsewhere for eight weeks each summer from 2009 to 2018 to help with the research.

The site includes two dig areas; the published findings are about artifacts found in area A. In the lower part of that area, researchers uncovered several hundred artifacts, including stone tools; charcoal; fire-cracked rock; and bone fragments likely from medium- to large-bodied animals, Davis said. They also found evidence of a fire hearth, a food processing station and other pits created as part of domestic activities at the site.

Over the last two summers, the team of students and researchers reached the lower layers of the site, which, as expected, contained some of the oldest artifacts uncovered, Davis said. He worked with a team of researchers at Oxford University, who were able to successfully radiocarbon date a number of the animal bone fragments.

The results showed many artifacts from the lowest layers are associated with dates in the range of 15,000 to 16,000 years old.

“Prior to getting these radiocarbon ages, the oldest things we’d found dated mostly in the 13,000-year range, and the earliest evidence of people in the Americas had been dated to just before 14,000 years old in a handful of other sites,” Davis said. “When I first saw that the lower archaeological layer contained radiocarbon ages older than 14,000 years, I was stunned but skeptical and needed to see those numbers repeated over and over just to be sure they’re right. So we ran more radiocarbon dates, and the lower layer consistently dated between 14,000-16,000 years old.”

The dates from the oldest artifacts challenge the long-held “Clovis First” theory of early migration to the Americas, which suggested that people crossed from Siberia into North America and traveled down through an opening in the ice sheet near the present-day Dakotas. The ice-free corridor is hypothesized to have opened as early as 14,800 years ago, well after the date of the oldest artifacts found at Cooper’s Ferry, Davis said.

“Now we have good evidence that people were in Idaho before that corridor opened,” he said. “This evidence leads us to conclude that early peoples moved south of continental ice sheets along the Pacific coast.”

Davis’s team also found tooth fragments from an extinct form of horse known to have lived in North America at the end of the last glacial period. These tooth fragments, along with the radiocarbon dating, show that Cooper’s Ferry is the oldest radiocarbon-dated site in North America that includes artifacts associated with the bones of extinct animals, Davis said.

The oldest artifacts uncovered at Cooper’s Ferry also are very similar in form to older artifacts found in northeastern Asia, and particularly, Japan, Davis said. He is now collaborating with Japanese researchers to do further comparisons of artifacts from Japan, Russia and Cooper’s Ferry. He is also awaiting carbon-dating information from artifacts from a second dig location at the Cooper’s Ferry site.

“We have 10 years’ worth of excavated artifacts and samples to analyze,” Davis said. “We anticipate we’ll make other exciting discoveries as we continue to study the artifacts and samples from our excavations.”


The Cooper’s Ferry site

From the paper titled “Geoarchaeological context of late Pleistocene and early Holocene occupation at the Cooper’s Ferry site, western Idaho, USA“, by Loren G. Davis & Charles E. Schweger (2004) we read:

“Abstract Archaeological excavations at the Cooper’s Ferry site (10IH73), located in the lower Salmon River canyon of western Idaho, revealed a stratified sequence of cultural occupations that included a pit feature containing stemmed points. However, radiocarbon ages determined on charcoal and bone in the pit feature range between ca. 12,000 yr B.P. and 7300 yr B.P. By considering the effects of postdepositional processes on dated samples, and by comparing the lithostratigraphy, pedostratigraphy, and stable isotope geochemistry of pedogenic carbonates from Cooper’s Ferry with other well‐dated stratigraphic sections in the canyon, site geochronology is clarified. Based on the presence of key radiocarbon ages and distinctive stratigraphic criteria, we argue that the initial occupation and interment of lithic artifacts in a pit feature at Cooper’s Ferry occurred during the late Pleistocene, between ca. 11,410 and 11,370 yr B.P., and not during the early Holocene. Records of geomorphic change and paleoenvironmental proxy data from the site reveal that early occupation in the lower Salmon River canyon corresponds with evolving riparian ecosystems, which must be considered as a contextual aspect of local prehistoric cultural ecology.”

From the paper titled “Context, Provenance and Technology of a Western Stemmed Tradition Artifact Cache from the Cooper’s Ferry Site, Idaho“, by Loren G. Davis, Alex Nyers & Samuel Willis (2014) we read:

“Abstract The discovery of an artifact cache containing Western Stemmed Tradition (WST) projectile points in a clearly defined pit feature at the Cooper’s Ferry site offers a unique perspective on early lithic technology and logistical organization in western North America. A description and analysis of the cache feature reveals several new insights, including: a rocky cairn capped the surface of the pit feature; some of the artifacts were made from cryptocrystalline silicates found 16 km away; debitage analysis, including aggregate and attribute based measures, identified two distinct lithic reduction stages present in the cache; new radiocarbon assays suggest that the cache is probably not early Holocene in age and may date to associated age estimates of 11,410–11,370 radiocarbon years before present (B.P.). Unlike Clovis caches, the Pit Feature A2 cache at Cooper’s Ferry appears to be a generalized toolkit that was probably placed at the site for future use. If the 11,410–11,370 radiocarbon years B.P. assays date the creation of the Pit Feature A2 cache, then its creators were probably not pioneers in the lower Salmon River canyon but possessed local knowledge about the landscape and raw material sources; these patterns suggest greater time depth for WST foragers.”

The Cooper’s Ferry site on the map

From the paper titled “Late Upper Paleolithic occupation at Cooper’s Ferry, Idaho, USA, ~16,000 years ago“, by Loren G. Davis et al. (2019) we read:

“Archaeological evidence predating the appearance of the Clovis Paleoindian tradition (CPT) in the Americas by ~13,250 calibrated years before the present (cal yr B.P.) is found at a small number of reliably dated sites. These sites share technological attributes similar to Late Upper Paleolithic (LUP) sites in northeastern Asia, including flake- and blade-based stone tool traditions, use of informal lithic tools, lack of fluted bifacial technology, and use of stemmed and lanceolate projectile points.”

“The Cooper’s Ferry site is located within an alluvial terrace at the confluence of Rock Creek and the lower Salmon River of western Idaho.”

“The Cooper’s Ferry site radiocarbon chronology for LU5 to LU3 is based on 21 ages from charcoal and bone samples recovered in situ outside of cultural pit features. AMS dating indicates that LU5 dates from ~9250 to 9000 cal yr B.P., LU4 dates from ~11,930 to 10,410 cal yr B.P., and LU3 dates between ~15,660 and 13,260 cal yr B.P. Optically stimulated luminescence (OSL) analysis of potassium feldspar grains sampled from LU5, LU4, and upper LU3 sediments dated to 12,170 ± 2320 years ago (±1 SD), 12,730 ± 2400 years ago, and 13,710 ± 2620 years ago, respectively.”

NovoScriptorium: LU stands for “lithostratigraphic unit”

“We uncovered and mapped 189 lithic artifacts in situ within LU3, including 161 pieces of debitage, 27 stone tools, and 1 piece of fire-cracked rock (FCR), and also 86 faunal bone fragments and 1 river mussel shell fragment.”

“Three pit features were excavated into the LU3 surface, including pit feature A2 (PFA2), F134, and F135. Pit feature A2 originates from the surface of LU3, as evidenced by a gravel cairn that marks its top. It contains 4 WST projectile points, 1 core, 1 hammerstone, 3 blades, 2 unifaces, 2 modified flakes, 724 debitage pieces, and 65 bone fragments.”

“The artifacts contained within LU3 and PFA2 temporally precede and partially overlap with the CPT but represent a separate technological tradition distinguished by flake- and macroblade based lithic tool production, including but not limited to stemmed, lanceolate, and foliate projectile point forms; Levallois-like and discoidal unidirectional and multidirectional core design; predetermined flake and macroblade blanks; and flake and blade tools. These technological attributes are seen among North and South American sites that predate the CPT, most recently discovered in stratified context beneath Clovis artifacts at the Gault and Friedkin sites in Texas.”

“A small number of reliably dated archaeological sites now provide evidence that humans were present in the Americas by at least 14,500 cal yr B.P. and even before 15,000 cal yr B.P.”

“Cooper’s Ferry provides direct evidence for human settlement south of Late Wisconsinan ice sheets in the upper Columbia River basin before the earliest hypothesized opening of the IFC at ~14,800 cal yr B.P. This evidence refutes the IFC hypothesis* and leads us to deduce that humans initially migrated into the Americas along the Pacific coast. This does not preclude subsequent human migrations through the IFC at a later time, as suggested by paleogenomics, but such possible population movements do not represent the initial peopling of the Americas.”

*NovoScriptorium: IFC stands for “ice-free corridor” and refers to the hypothesis of human migration from eastern Beringia southward through a deglaciated ice-free corridor.

Artifacts from the Cooper’s Ferry site

Research-Selection for NovoScriptorium: Philaretus Homerides & Maximus E. Niles

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