In 1959, Ruth Dee Simpson showed stone fragments from California's Calico Hills to Louis Leakey. He argued that they were human-made tools more than 100,000 years old, reasoning from Indigenous American linguistic diversity. Leakey studied the site in 1963; National Geographic-supported excavations ran from 1964 to 1970. The resulting dates concern surrounding deposits, not the stones themselves. The controversial “Calico Early Man Site” remains disputed, with most archaeologists treating the pieces as geofacts rather than tools.
Louis Leakey's disputed claim of 100,000+ year-old tools at Calico, California
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Key facts
- In 1959, Ruth Dee Simpson showed stone fragments from Calico Hills to Louis Leakey; 1963 was when Leakey studied the site.
- Leakey argued that the fragments were human-made tools more than 100,000 years old, using Indigenous American linguistic diversity and an estimated 35,000–100,000-year development period rather than directly dating the stones.
- National Geographic-supported excavations ran from 1964 to 1970 and yielded roughly 70,000 fractured stone specimens.
- The fractured stones included chalcedony, chert, jasper and quartz, materials suitable for toolmaking.
- Thermoluminescence results of about 135,000 years, uranium-series results of about 200,000 years and a beryllium-10 result of 197,000 ± 20,000 years date the associated deposits, not the stones directly.
- Most archaeologists reject the human-made-artifact interpretation and regard the Calico pieces as geofacts; the site remains disputed.
Sources
sapiens.org
Linked in video description
On and Off the Beaten Path: Calico Early Man sitedvidshub.net
With the help of world-renowned archaeologist Dr. Louis Leakey, the Early Man Site was established in 1964 and has been actively excavated for ...
Calico Mountains Archaeological Site Overviewdesertmoon.net
This is the only New World site where Dr. Louis Leakey managed and supervised the excavations. The three Master Pits containing the original excavations are ...
San Bernardino County history: Calico Early Man Sitemain.sbcounty.gov
In 1963, Leakey studied the site and concluded that the pieces of rock found at Calico “unquestionably” were human-made artifacts. The area ...
BLM to reopen Calico Early Man Siteblm.gov
Made famous by the world-renowned paleoanthropologist, Louis Leakey's work at the site between 1964 and 1970,
Calico Early Man Siteen.wikipedia.org
In the 1960s, anthropologist, Louis Leakey, proposed the site contained artifacts created by early man, however, this proposal is not accepted by most ...
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