“It is clear that the mountains were once under the ocean because the sedimentary rocks that form the tops of most mountains contain marine fossils. For example, Mount Everest is topped with marine crinoid (sea lily) fossils embedded in limestone.
This means that Mount Everest and the other high mountains in our present world, with their sedimentary rocks and fossils, rose up out of the floodwater during the later stages of the Flood. “ Written by Michael Oard.See article below:
https://creation.com/how-did-the-waters-of-noahs-flood-drain