The antediluvian (or pre-diluvian) period – meaning "before the deluge" – is the period referred to in the Bible between the Creation of the Earth and the Deluge (flood) in the biblical cosmology. The narrative takes up chapters 1-6 (excluding the flood narrative) of Genesis. The term found its way into early geology and lingered in science until late Victorian era. Colloquially, the term is used to refer to any ancient and murky period.
Timing the antediluvian period 
The biblical flood 
In the Christian Bible and Hebrew Torah, the antediluvian period begins with the Creation according to Genesis and ends with the destruction of all life on the earth except those saved with Noah in the Ark. According to Bishop Ussher's 17th-century chronology, the antediluvian period lasted for 1648 years, from creation at 4004 BC and the flood at 2348 BC. The elements of the narrative include some of the best-known stories in the Bible—the Creation itself, Adam and Eve, and Cain and Abel—followed by the genealogies tracing the descendants of Cain and Seth, the third son of Adam and Eve. (These genealogies provide the framework for the biblical chronology, in the form A begat B in his Xth year).
The Bible speaks of this era as being a time of great wickedness. There were Gibborim (giants) in the earth in those days as well as Nephilim; some translations identify the two as one and the same. The Gibborim were unusually powerful; Genesis calls them "heroes of old, men of renown;" (Enoshi Ha Shem). The antediluvian period ended when God sent the Flood to wipe out all life except Noah, his family, and the animals they took with them. Nevertheless, the Nephilim (literally meaning 'fallen ones', from the Hebrew root n-f-l 'to fall') reappear much later in the biblical narrative, in Numbers 13:31-33 (where the spies sent forth by Moses report that there were Nephilim or "giants" in the Promised Land).
In early geology 
Early scientific attempts at reconstructing the history of the Earth were founded on the biblical narrative and thus used the term Antediluvian to refer to a period understood to be essentially similar to the biblical one. Early scientific interpretation of the biblical narrative divided the Antediluvian into sub-periods:
- Pre-Adamitic (the first 5 days, Gen 1:1 to Gen 2:3)
- Primary (the formation of the physical universe and the earth)
- Secondary (creation of plants and animals)
- Adamitic (or Tertiary, from the creation of man to the Great Flood; Gen 2:5 to Gen 7.8), corresponding to St. Agustine's First Age of his Six Ages of the World
Prior to the 19th century, rock was classified into three main types: primary or primitive (igneous and metamorphic rock), secondary (sedimentary rock) and tertiary (sediments). The primary rocks (like granite and gneiss) are void of fossils and were thought to be associated with the very creation of the world in the primary Pre-Adamitic period. The secondary rocks, often containing copious fossils, though human remains had not been found, were thought to have been laid down in the secondary Pre-Adamitic period. The tertiary rocks (sediments) were thought to have been put down after Creation and possibly in connection to a flood event, and were thus associated with the Adamitic period. The post-flood period was termed the Quaternary, a name still in use in geology.
As mapping of the geological strata progressed in the early decades of the 19th century, the estimated lengths of the various sub-periods were greatly increased. The fossil rich Secondary Pre-Adamitic period was divided up into the Coal period, the Lias and the Chalk period, later expanded into the now-familiar geologic time scale of the Phanerozoic. The term antediluvian was used in natural science well into the 19th century and lingered in popular imagination despite increasingly detailed stratigraphy mapping the Earth's past, and was often used for the Pleistocene period, where humans existed alongside now extinct megafauna.
The antediluvian world 
Creationist interpretation 
- People lived much longer than those alive today, typically between 700–950 years, as reported in the genealogies of Genesis;
- The Earth contained many more people than the Earth contained in 1696. Whiston calculated that as many as 500 million humans may have been born in the antediluvian period, based on assumptions about lifespans and fertility rates;
- There were no clouds or rain. Instead, the Earth was watered by mists which rose from the Earth. (Another interpretation is that the Earth was covered completely by a global cloud layer; the upper waters mentioned in the Creation. This is commonly called the Canopy view).
In 19th-century science 
During the late 18th and early 19th centuries, the understanding of the nature of early Earth went through a transformation from a biblical or deist interpretation to a scientific one. Even back in the early 18th century, Plutonists had argued for an ancient Earth, but the full impact of the depth of time involved in the Pre-Adamitic period was not commonly accepted until uniformitarianism as presented in Charles Lyell's Principles of Geology of 1830. While vast aeons of time were involved, the narrative of the pre-Adamitic world was still influenced by the biblical story of creation in this transition. A striking example is a description from "Memoires of Ichtyosauri and Plesiosauri", 1839:
An "ungarnished and desolated world which echoed the flapping of [pterodactyl] leathern wings" was lit by "the angry light of supernatural fire", shining on a "sunless and moonless" world, before the creation of these heavenly "lights".
The antediluvian monsters 
From antiquity, fossils of large animals were often quoted as having lived together with the giants from the Book of Genesis: e.g. the Tannin or "great sea monsters" of Gen. 1,21. They are often described in later books of the Bible, especially by God Himself in the Book of Job: e.g. Re'em in verse 39,9, Behemoth in chapter 40 and Leviathan in chapter 41. With the advent of geological mapping in the early 19th century, it became increasingly obvious that much of the fossils associated with the "secondary" (sedimentary) rock, notably large animals like Ichthyosaurs, Mosasaurs, Pliosaurs and the various giant mammals found when excavating the Catacombs of Paris, were neither those of giant humans nor of any extant animals. The geologists of the day increasingly came to use the term Antediluvian only for the younger strata containing fossils of animals resembling those alive today.
Other uses 
- The term is also used in the field of Assyriology for kings, according to the Sumerian king list, supposed to have reigned before the great flood.
- The adjective antediluvian is sometimes used figuratively to refer to anything that is of great age and/or outmoded. H. P. Lovecraft was particularly fond of the term, using it frequently in his horror stories.
- In Charles Stross's Saturn's Children the religious order who believe in evolution refer to the antediluvian period as the time in which man lived alongside Tyrannosaurs.
- Atlantis: The Antediluvian World is a 1882 book by Ignatius L. Donnelly that attempted to establish that all known ancient civilizations were descended from Atlantis. Many theories mentioned in the book are the source of modern-day concepts about Atlantis.
- The Antediluvian Steampunk / Biblical Fantasy series by C.D. Sutherland: The Dragoneers (2011): Book One of the Chronicles of Susah,  and The Lost Dragoneer (2013): Book Two of the Chronicles of Susah.  is set eighty years before the great flood. The series is built around the daughter of Noah, in a world with technologies equal to or better than modern times awaiting eventually destruction by the deluge. Most interesting is a presence of an external ice shield, frozen water, surrounding the Earth at low Earth orbit altitudes.
- In the tabletop role-playing game Vampire: The Masquerade the Antediluvians are the early vampires that lived in the pre-flood world and the supposed progenitors of the original clans.
See also 
- Abbott, W. M. (1990). "James Ussher and "Ussherian" episcopacy, 1640–1656: the primate and his Reduction manuscript." Albion xxii: 237-59.
- Ussher, J, 1650. Annals of the World: James Ussher's Classic Survey of World History ISBN 0-89051-360-0 (Modern English republication, ed. Larry and Marion Pierce, Green Forest, AR: Master Books, 2003)
- Rudwick, M.J.S (1992): Scenes from Deep Time: Early Pictorial Representations of the Prehistoric World, University of Chicago Press, 280 pages. Except from Google Books
- Graeme Dunphy (2010). "Six Ages of the World". In Graeme Dunphy. Encyclopedia of the Medieval Chronicle. Leiden: Brill. pp. 1367–1370. ISBN 90 04 18464 3.
- Gohau, G. (1991) A History of Geology (Revised edition). Rutgers University Press. 259 pages ISBN 0-8135-1666-8
- Whiston, William (1696). A New Theory of the Earth, From its Original, to the Consummation of All Things, Where the Creation of the World in Six Days, the Universal Deluge, And the General Conflagration, As laid down in the Holy Scriptures, Are Shewn to be perfectly agreeable to Reason and Philosophy. London: Benjamin Tooke.
- Morris, H.M & Whitcomb, J.C. (1961): The Genesis Flood: The Biblical Record and Its Scientific Implications, Presbyterian & Reformed Publishing, Philadelphia, (ISBN 0-8010-6004-4)
- Sutherland, C.D (2011): The Dragoneers: The Chronicles of Susah: Book One, Narrow Way Press LLC, Bossier City (ISBN 978-1-9373-6603-2
- Uniformitarianism: World of Earth Science
- Hawkins, T. (1834): Memoires of Ichtyosauri and Plesiosauri: Extinct Monsters of the Ancient Earth. Cited in Rudwick, 1992
- Genesis Park: Dinosaurs in the Bible
- Mechon-Mamre: A Hebrew - English Bible According to the Masoretic Text and the JPS 1917 Edition
- Rudwick, M.J.S (1989): Encounters with Adam, or at least the hyaenas: Nineteenth-century Visual Representation of Deep Past. In History, humanity and evolution: Essay for John C. Greene (ed. Moore, J.R), Cambridge University Press, pp 231-251
- The Dragoneers (2011) ISBN/EAN13: 1937366030 / 9781937366032 http://www.amazon.com/dp/B006GDWQZ2
- The Lost Dragoneer (2013) ISBN/EAN13: 1937366049 / 9781937366049 http://www.amazon.com/dp/B00AWJW0O8