No single method, applied in isolation, could have achieved this confidence.

Each line of evidence constrained and confirmed the others.

The Arlington Springs individual was not a 10,000-year-old person whose bones had been reworked into older sediments.

He was a person who had lived, died, and been incorporated into those sediments at the end of the Pleistocene, approximately 13,000 calendar years ago.

And he was on an island.

The Water That Had To Be Crossed

The geographic fact that gives the Arlington Springs age its continental significance has been mentioned already, but it requires fuller treatment.