I remember an elder giving a talk about the bible's account of the flood can be substantiated by science in that archaeologists found sea shells on the highest parts of the Himalayas surrounding Everest . True but he didn't mention that the sea shells and fossils were feet thick indicating that the ground was once an ocean floor bed.
Take this with a grain of salt as i'm not an expert, but I'm pretty sure that if there was a massive downpour like that, you would not all of a sudden see sea shells on top of mountains. Sea shells don't swim around in that manner. It would most likely take thousands of years for sea shell populations to make their way that high