| Answer | Crossword Clue |
|---|---|
| AEON | Part of the earth's history |
| EON | Period in the earth's history |
| EON | Phanerozoic ... (current period in the earth's history) |
| PERMIAN | Period marked by the largest mass extinction in earth's history |
| catastrophism | The theory that changes in the earth's crust during geological history have resulted chiefly from sudden violent and unusual events |
| geology | The science that deals with the earth's physical structure and substance, its history, and the processes that act on it |
