Age constraints on alleged "footprints" preserved in the Xalnene Tuff near Puebla, Mexico

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). Additional paleomagnetic measurements of individual millimeter-size lapilli indicate that the pyroclastic grains within the Xalnene Tuff have not been disturbed or rotated since their initial deposition, thereby ruling out the possibility that the tuff was reworked by wave action along the shores of an ancient lacustrine environment. This and other evidence indicate that the marks observed in the stone quarry site are not human ichnofossils.

Are you aware that our magnetic field has almost vanished (comparatively speaking)?

The thing about “models” is they essentially stand in the place of observable, measurable phenomina. When you see the term ‘model’ used it means that there is no empiricity to examine, and someone is extrapolating from gueses to pipe dreams.

Models are unnecessary when there are data to work with.

The models are from measurable historical data. And as far as the magnetic field almost gone what up with that? And what difference does that have to do with a pole flip? Maybe it is what is needed for the poles to flip it weakens to the point that they flip have you considered that and you have yet to give any evidence other than what you claim can and can not happen.

Data to work from

Paleomagnetism is the study of the record of the Earth's magnetic field preserved in various magnetic minerals through time. The study of paleomagnetism has demonstrated that the Earth's magnetic field varies substantially in both orientation and intensity through time. en.wikipedia.org/wiki/Paleomagnetism

paleomagnetic - Of or pertaining to paleomagnetism en.wiktionary.org/wiki/paleomagnetic

1. The fixed orientation of a rock's crystals, based on the Earth's magnetic field at the time of the rock's formation, that remains ... college.cengage.com/geology/resources/geologylink/glossary/p.html

Earth's magnetic field of the past as shown by natural remnant magnetism in rocks; paleomagnetic reversals of polarity are a common feature, and reversals can be used as stratigraphic markers. academic.emporia.edu/aberjame/ice/gloss.htm

The time correlative orientation of magnetic materials within the earth's This has allowed scientists to trace continental drift over the ages. canoesaskatchewan.rkc.ca/geology/glossary.htm

دیرینمغناتیس dirin-meqnâtis Fr.: paléomagnétisme The study of natural remanent magnetization in order to determine the intensity ... aramis2.obspm.fr/~heydari/dictionary/index.php

The record of ancient magnetism preserved in rock. www.wwnorton.com/college/geo/earth2/glossary/p.htm

It seems awfully silly to have all these people studying something that has never happened. Don't ya think?

What would restore the field?

Your “historical data” is assumption, not data, since there is no witness to confirm it, thus the ‘model’ remains imaginative Sci-Fi.

Anyone can make a model say anything they want (vz: global warming).
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“It seems awfully silly to have all these people studying something that has never happened. Don’t ya think?”

It sure does, and we are paying for this clown show, dearly. That is the point. The randomly gathered deep core samples that have been gathered, mostly as routine prep in oil and gas drilling sites, all says no polar changes have happened, since their variation is within the cyclic swing shown in declination tables.

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