http://cayman.globat.com/~bandstexas.co ... 202008.pdf
Conclusions
All of the proper indicative diatom/cyst fossils associated with the ancient artifacts at Hueyatlaco are present in the correct places (and absent from the places where they should not occur) to be consistent with a Sangamonian Interglacial or older (Illinoian Glacial) age.
Those who would wish to argue against the case for the great antiquity (prior to the Last Ice Age) of humanity in the New World by attacking the veracity of the compelling diatom and chrysophyte evidence have picked the wrong place to make such an argument at Hueyatlaco No other archaeological site in world is associated with such a variety of age diagnostic diatoms and chrysophytes and in such profusion. Moreover, the Valsequillo area has the most complicated non-marine diatomaceous sequence in the world: 22 beds compressed into less than 2 million years and into less than 30 m.