When the dove returned to him in the evening, there in its beak was a freshly plucked olive leaf! Then Noah knew that the water had receded from the earth.
Genesis 8:11 (NIV)
The rabbis wondered about this olive leaf the dove found, because in the already unlikely story of a global flood, it is unlikely that an olive tree should produce leaves so quickly.
They point to Ezekiel and suggest that perhaps the Mount of Olives and Israel (Eden) were never flooded.
Again the word of the Lord came to me: “Son of man, say to the land, ‘You are a land that has not been cleansed or rained on in the day of wrath.’
Ezekiel 22:23-24 (NIV)