Chronology of the Flood


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The Overall Chronology

Chapters 7-8 of Bereshit describe the flood at length, providing a detailed dating of many of its stages.  The event took place over a period of about twelve months, with the flood beginning on the 17th of the second month and ending a little over a year later, on the 27th of the second month.  The text shares other significant dates and time periods as well:

  • Dates – The ark landed on the 17th of the seventh month (8:4), the mountain tops appeared on the 1st of the tenth month (8:5), and the land dried on the 1st of the first month (8:13).
  • Time frames – The chapters mention 40 days of rain (7:12, 17), 150 days of increasing waters (7:24) and 150 days in which they decreased (8:3), a 40 day wait before Noach opens his window (8:6) and then 14 or 21 days worth of sending the birds (8:7-11).1

It is not clear, though, how all these dates work together and how the various events fit into the time frames allotted for them.

The table below summarizes the dates and time frames:

תאריכים ומערכת של זמנים המאורע
י"ז לחודש השני התחלת המבול (ז:יא)
40 יום גשם (ז:יב,יז)
150 יום "ויגברו המים על הארץ" (ז:כד)
150 יום "ויחסרו המים מקצה 150 יום" (ח:ג)
י"ז לחודש השביעי התבה נחה על הררי אררט (ח:ד)
א' לחודש העשירי "נראו ראשי ההרים" (ח:ה)
40 יום לפני שפתח נח את חלון התיבה (ח:ו)
7 יום (ב' או ג' פעמים) שליחות העורב והיונים (ח:ז-יב)
א' לחודש הראשון "חרבו המים מעל הארץ" (ח:יג)
כ"ז לחודש השני "יבשה הארץ" (ח:יד)
Dates and Time-frame Event
17th of the second month Beginning of flood (7:11)
40 days Rain (7:12, 17)
150 days "The waters were strong upon the earth" (7:24)
150 days "And the waters decreased after 150 days..." (8:3)
17th of seventh month Landing of the ark (8:4)
1st of tenth month Appearance of mountain tops (8:5)
40 days Before opening the window (8:6)
7 days (x2 or 3)
Sending of raven and doves (8:7-12)
1st of first month Removing of ark's cover and drying of the land (8:13)
27th of second month Land dries and Noach leaves ark (8:14)

Overlapping events

If all of the various time frames mentioned represent distinct periods of time, they do not fit into the allotted year,2 suggesting that some of them must overlap.  However, the text does not clarify which might overlap:

  • Are the 40 days of rain included in the 150 days of strong waters, or do they precede them, as might be assumed if the verses are sequential?
  • Were there really two distinct sets of 150 days, or does the text simply mean that the waters decreased after the initial 150 days?  If the former, one would have expected the end of the second set to coincide either with the drying of the land on the 1st of the first month or the end of the flood on 27th of the second month. However, neither date works with the chronology given in the verses.

Specific events

  • Landing of the Ark – As the ark could not land until the waters began to recede, how do 150 days, let alone 190,3 fit into the period between 17th of the second month (the start of the flood) and the 17th of the seventh month (when the ark landed)?  In a fixed Hebrew lunar calendar, where months alternate between 29 and 30 days, there is at most 147-149 days in any five month period,4 so neither option would seem to work with the text!
  • Sending of the birds – The text (8:6) states that the birds were sent "after forty days", and the immediately aforementioned event is the appearance of the mountains tops on the 1st of the tenth month (8:5). However, if they were sent forty days after the mountain summits were already visible, why could the first dove not find a resting place?  In addition, this dating would leave about a month after their return before Noach removed the cover of the ark and the drying of the land on the 1st of the first month (8:13), making one wonder why he waited.5
The Approaches page will lay forth several possible reconstructions of the chronology of the flood in an attempt to answer the above questions.