Last paragraphs of chapter 2

The empirical grounds of Cuvier’s theory have, by now, largely been disproved. The physical evidence that convinced him of a “revolution” just prior to recorded history (and that the English interpreted as proof of the Deluge) was, in reality, debris left behind by the last glaciation. The stratigraphy of the Paris basin reflects not sudden “irruptions” of water but rather gradual changes in sea level and the effects of plate tectonics. On all these matters Cuvier was, we now know, wrong. At the same time, some of Cuvier’s most wild-sounding claims have turned out to be surprisingly accurate. Life on earth has been disturbed by “terrible events,” and “organisms without number” have been their victims. Such events cannot be explained by the forces, or “agents,” at work in the present. Nature does, on occasion, “change course,” and at such moments, it is as if the “thread of operations” has been broken. Meanwhile, as far as the American mastodon is concerned, Cuvier was to an almost uncanny extent correct. He decided that the beast had been wiped out five or six thousand years ago, in the same “revolution” that had killed off the mammoth and the Megatherium. In fact, the American mastodon vanished around thirteen thousand years ago. Its demise was part of a wave of disappearances that has come to be known as the megafauna extinction. This wave coincided with the spread of modern humans and, increasingly, is understood to have been a result of it. In this sense, the crisis Cuvier discerned just beyond the edge of recorded history was us.

In the last paragraph of chapter 2,( Elizabeth Kohlbert says that the paleontologist was right - that there was a great event just before recorded time. What caused this great event? (Type on word in the blank - the one thing that caused the event. Spell the word correctly!)