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Dating

Radiometry

Radiocarbon

C14 is continuously generated (UV rays in upper atmosphere +++(hitting what??)+++), and destroyed.
When organic matter dies; C14 absorption stops (no creation). By measuring the fraction of C14 atoms, can figure out age of death.

Works on organic materials up to about 60,000 years of age. material is destroyed during the test. samples are also easily contaminated - so need to clean meticulously.

Potassium-argon dating

date volcanic materials ranging from less than 100,000 to more than 4 billion years old.

Rubidium-strontium dating

date from few million to a few billions of years old

Dendrochronology

Tree ring dating

Genetic dating

Graham Hancock’s theory about lost ancient Pleistocene civilizations which seeded future civilizations - Razib points out that as a geneticist, we would see a record of this in the genomes of domesticated plants or animals. But we don’t see it (except in dog), ruling out “lost civilizations.”