Great Flood of Noah
The Great Flood of Noah, or Flood of Noah, is a Biblical event narrated in the book of Genesis and later witnessed as both historical and allegorical in the New Testament and in Church Tradition. This event was a cataclysm which took place in the 600th year of Noah's life; according to a plane reading of the Septuagint this catastrophe should have flooded the entire earth some time around 3250 BCE exterminating all civilizations and animals except for eight people, two couples of all impure animals and seven pure animals who survived on board of the Ark of Noah. The Masoretic Text gives for the Deluge a date around 2300 BC (which seems inconsistent with the data on the most ancient civilizations such as Ancient Egypt) and the Samaritan Pentateuch places it around 2900 BC.
The Biblical Premise to the Flood
The Bible states in Genesis 7-8 that in the 10th generation from Adam, God found the earth completely corrupted by sin. Violence was so dominant because of the "nephilim" (hybrids of the "sons of God" and the "daughters of man"). Since all humans in that generation were evil, God decided to wipe out all flesh with a catastrophic flood. Noah, son of Lamech, was appointed by God as the one who will save mankind and animalkind, being "just in his generation". For that reason, Noah was instructed to build a gigantic ship, named an Ark, on which Noah, together with his three sons Shem, Ham and Japheth with their respective wives were to find a refuge. Noah was also instructed to collect representatives of pure and impure terrestrial animals and birds so that they could reproduce anew on the planet after the cataclysm.
The Flood Narrative
The Ark was prepared with gopher wood (possibly acacia) and bitumen and was some 300 m long. We don't know how much it took for Noah and his sons to built this huge timber vessel, though.
The flood began on the 17th of the first month, but we don't know which calendar the Author refers in the text. After Noah and the others entered the Ark, God sent the water from two different sources: the "windows" in heaven (rain) and the "fountains of the deep", maybe tsunamis or gysers. Anyway, the water submersed the entire planet for 40 days, the waters remained for 150 days and then began to decrease. After sanding out of the Ark two birds (a raven and a dove) Noah verified that the waters had receded: he is now ready to leave the vessel.
After the Deluge
The Ark is said to have landed in the mountains of Ararat, in Armenia. Although this territory is extended, tradition ascribes the landing site on what is now known as Mt Ararat. Noah at this time sealed the so-called Noahide Covenant with God, sacrificing some of the animals on an altar. God gave a rainbow as a sign so that God might remember of his promise not to flood the earth again as a punishment for humanity.
What can be noticed in the Biblical Genealogies is a sensible shortening of the lifespans of the Patriarchs starting with Arphaxad. Probably God wants to reveal that a change in the climate and nature of our world after the deluge took place so that health was now compromised.
The Flood and Church Tradition
The event of the flood had a great allegorical importance for the Apostles and the Church Fathers, since Peter himself indicates the Ark as a type for Christ and the Church, and the flood as a type for baptism.
Jewish authors Philo and Flavius Josephus as well as many Church Fathers (such as Justin Martyr, Theophilus of Antioch, Tertullian, Gregory of Nazianzus, John Chrysostom and Augustine of Hippo) firmly believed in a global extent of the flood  The dimensions of the Ark were speculated as allegorical by Hippolitus, who understood them as a sign for the timing of Christ's coming after 5500 years from Adam, while Origen invented or reconstructed a pyramidal form for the vessel.
Many Christian authors identified the landing place somewhere in Armenia or Arabia: Mt.Qardu seemed to be favoured by Hippolytus of Rome and Ephrem the Syrian while Epiphanius identified it with Mt. Lubar.
Historicity of the text
Creationists and biblical literalists tend to recognize this passage as historical and accurate. Proofs from Tradition and from the words of the Old and New Testament give credit to some historicity of the account, but many varying opinions have grown to speculate on the why's and how's of the Deluge.
The main two categories of interpretation are the global flood theory and the local flood theory. The first exegetical school teaches that a catastrophic world-wide submersion of the dry lands really occured, so that no survivors escaped the cataclysm except for those on the Ark. The second position states that either humanity was concentrated in Mesopotamia so that a local flood in the Tigris-Euphrates valley would have wiped out all humans, or on the contrary that by "all the earth" the Bible understands "all the region" requiring the extinction of only one civilization. That some planetary flood or dramatic climatic changed brought many civilizations to extinction is indeed possible. There are lots of independent flood myths around the world, with a variety of data which doesn't separate these texts from the Biblical narrative too much, so that a common origin for this myth is to be looked for in the geological history of the earth.
- The Epic of Gilgamesh