On my reading, Genesis does not stipulate a 6000 year old earth. Genesis 1 is not even in the same time order that we, as humans, experience. As for a global flood, I don't see how present-day science can claim to have ruled out such a thing beyond a reasonable doubt. We know there have been cataclysmic events on this planet in its history, some of which have been associated with comet/meteor strikes. It is thought that the dinosaurs met their demise as the result of global climate change occasioned by the latter. A massive comet or meteor landing in the ocean could cause a catastrophic rise in sea levels. Present-day science is not in a position to rule this possibility in, nor rule it out.
Science has falsified neither of these two points.
I was most specific: "A global flood 4350 years ago."
Comets and meteors 65 million years ago do not apply. Neither does the Cambrian 500+ million years ago.
All it takes to rule out a global flood at 4350 years ago is something that persists across that time period. That can be DNA, culture (Egypt), soil layers, fauna and flora, etc.
There are many cases where there is continuity across the 4350 time period. As far as science is concerned, this disproves a global flood at that time period. (The early geologists seeking to prove the flood gave up about 1830.)
She blinded me with science.