Month and Day of The Flood?

[MarkyMark7]

Ok, I recently started re-reading Genesis and while reading Genesis 7 I read some very interesting things.
Genesis 7:11- In the six hundredth year of Noah's life, in the second month, on the seventeenth day of the month, on the same day all the fountains of the great deep burst open, and the floodgates of the sky were opened.
Before Exodus 12:2 the second month was Bul (or Marcheshvan) which in the equivalent to October.So, the Flood happened October 17, approximately (b/c many of us disagree on the Genesis geneologies) 1656 AAC (After Adam's Creation)?

Another thought:
From Genesis 7:11- "...on the the same day all the fountains of the great deep burst open..." So the flood waters came from rain and underground waters? Never heard that before.

[oscarsiziba]

There is this school of thought that says at creation there was no rain,but just dew from under the ground,so this made it somehow unbelievable to Noah's generation to say rain would fall from above.It is said it was the first time fro rain to come down from heaven(time of flood) and that combined with the readily available fountains in the earth to work the destruction of the disobedient.