"Our work at Hueyatlaco has been rejected by most archaeologists because it contradicts that theory [evolution], period." -- Virginia Steen-McIntyre, tephrochronologist, March 30th 1981
"The problem as I see it is much bigger than Hueyatlaco. It concerns the manipulation of scientific thought and the suppression of 'Enigmatic Data,' data that challenges the prevailing mode of thinking." -- Virginia Steen-McIntyre, tephrochronologist, March 30th 1981
Renne, P.R., et al., Geochronology: Age of Mexican Ash with Alleged 'Footprints', Nature, 438, E7-E8, Dec 2005
A report of human footprints preserved in 40,000-year-old volcanic ash near Puebla, Mexico (http://www.royalsoc.ac.uk/exhibit.asp?id=3616&tip=1), was the subject of a press conference that stirred international media attention. If the claims (http://www.mexicanfootprints.co.uk) of Gonzalez et al. are valid, prevailing theories about the timing of human migration into the Americas would need significant revision. Here we show by 40Ar/39Ar dating and corroborating palaeomagnetic data that the basaltic tuff on which the purported footprints are found is 1.30 +/- 0.03 million years old.Feinberg, J.M., et al., Age Constraints On Alleged "Footprints" Preserved In the Xalnene Tuff Near Puebla Mexico, Geology, Volume 37, Number 3, Pages 267-270, Mar 2009
Impressions in a basaltic tuff located around Valsequillo Reservoir near Puebla, Mexico, have been interpreted as human and animal footprints along an ancient lakeshore, and are cited as evidence of the presence of humans in North America at 40 ka B.P. In this paper, we present new data that challenge this interpretation. Paleomagnetic analyses of the Xalnene Tuff, and lavas from the volcano from which it erupted, yield fully reversed magnetic polarities, indicating that the tuff was deposited prior to the last geomagnetic reversal (the Brunhes-Matuyama ca. 790 ka). 40Ar/39Ar dating of Xalnene lapilli and lava from the source volcano yields indistinguishable ages of ~1.3 Ma, consistent with a period of reversed magnetic polarity (C1r.2r).