Antediluvian:
The Antediluvian (alternatively Pre-Diluvian or Pre-Flood, or even Tertiary) period (meaning “before the deluge”) is the time period referred to in the Bible between the fall of humans and the Noachian Deluge (the Genesis Flood) in the biblical cosmology. The narrative takes up chapters 1–6 (excluding the flood narrative) of the Book of Genesis. The term found its way into early geology and lingered in science until the late Victorian era. Colloquially, the term is used to refer to any ancient and murky period. [Wikipedia]
Used in this 9 Chickweed Lane comic.