OK, here goes...The land on top of those seashells and such was NOT caused by the Flood, but by the separation of the continents in Peleg's time. This split occurred down the middle of the Atlantic primarily and in shoving the two hemispheres apart, also caused the enormous young mountain chains along the Pacific rim and the Pacific ring of fire. The tsunamis this movement caused moved immense amounts of earth and other materials.The shells themselves were fossilized after Noah's flood, as the Flood strata is far below them:Yes the earth is very young, but no, the Deluge did not cause all the strata we see today. If it did, how on earth can anyone explain the fact that in Europe we have enormous coal seams covered by an in situ fossilized sponge reef which stretches across about a third of the continent, and on top of which are multiple layers of dinosaur nests? The one flood did everything model is strongly refuted by the geological evidence as well as the Biblical mention of Peleg's time. To see what went on when the continents were separating, look for the catastrophes mentioned in the book of Job. Job was Jobab, Peleg's nephew, the thirteenth son of Joktan, Genesis 10 . He mentions, by the way, that a watch was kept on the sea. Why? Because of the giant tsunamis which went on for several hundred years. Because the waves pull far back before one comes in, keeping watch was the only way they could get to safety in time. You will find quite a few references to things they experienced during that time if you read the book looking for them.