I talked to one geologist who is mentioned in the awake about creation a few years ago. He is an elder too.
I asked him that I find it hard to believe in a global flood and if there are some geological signs or proofs for a global flood. He said he asks himself the same questions because there is no geological evidence for a global flood 2400 bc. So he tends to believe it was a local flood.
The bible does not speak against a local flood. The hebrew word for 'earth' means actually land (the people of that time did not think of a round blue planet when they thought about earth), the hebrew word for 'mountains' can also mean 'hills'.
Scientists Pitman and Ryan proved that the black sea was flooded about 7000 years ago. Flood myths could have started when the ice caps of the ice age melted.