Answer · confidence: partial

How were 1936 Folsom finds dated, and what did 1944 and 1987 reviews conclude?

Research question: How were the Folsom and first-campground finds described in 1936 dated and revised in later reports, and what did the 1944 and 1987 reviews conclude about them?

The verified facts cover the Folsom site only in part. In 1927, Harold J. Cook judged the Folsom bison beds to be late Pleistocene but said the evidence was not yet enough to fix their exact age ². The bison were later reclassified as Bison antiquus ³, and radiocarbon dates then available placed the Folsom complex at about 10,300 years B.P., replacing looser earlier estimates ⁴. A 2021 Bayesian revision using IntCal20 estimated the tradition lasted 355–510 years at the 68 per cent credible interval ¹. The verified facts do not describe the 1936 reports, the first-campground find, or the 1944 and 1987 reviews ²⁴; the newest fact is from 2021, about five years old as of October 2026 ¹.

Checked 2026-10-21. Only documented and supported facts are used.

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[1] documented

A 2021 study revised the Folsom age range by applying Bayesian modeling with IntCal20 to an updated set of Folsom radiocarbon dates, estimating the tradition lasted 355–510 years at the 68 per cent credible interval.

"We applied Bayesian modeling using IntCal20 to our updated set of Folsom dates and estimate that the Folsom tradition lasted for a period spanning between 355–510 years at the 68 per cent credible interval"

Bayesian Revision of the Folsom Age Range Using IntCal20 - University of Arizona

[2] supported

In 1927, geologist Harold J. Cook judged the Folsom bison beds to be a late Pleistocene deposit, while noting that the evidence was not yet enough to fix their exact age.

""while it is premature to express an opinion as to the exact age of these beds on present evidence ... the writer is of the opinion that this will prove to be a late Pleistocene deposit""

The Folsom site in retrospect

[3] supported

The Folsom bison, first examined by Cook as a Bison occidentalis-like animal, is later classified as Bison antiquus.

"Presently the bison is classified as Bison antiquus."

The Folsom site in retrospect

[4] supported

Radiocarbon dates then available assigned the Folsom complex an age of about 10,300 years B.P., a date that replaced the earlier, looser estimates.

"Radiocarbon dates presently available assign Folsom an age of about 10,300 years B.P. (Judge, in press)."

The Folsom site in retrospect