I saw that too. One thing I found interesting was the 2 or 3 foot layers of sediment left over from the Younger-Dryas period, covering the Clovis evidence.
This makes me wonder how deep/far should scientist dig to uncover evidence of past civilizations. Seems most are satisfied with shallow digs that only go back a few tens of thousands of years or looking for specimens uncovered in more ancient rock by erosion.
It's possible, with all the catastrophic events through history, evidence of man past may be lost forever. Aside from the fragments found now and then, we may never know how advanced man became between mass extinction events.
“We may never know how advanced man became between mass extinction events.”
My thought for a long time exactly. Also, what was the trigger for the change from 40 ky ice events to 100 ky ice events starting about a million years ago. Could there be a cometary long orbit cycle responsible? And have scientists or interested amateurs examined maps to detect other subtle comet type craters?