Him: The story of Noah’s flood is a myth. I can see no evidence on Earth for a global flood. It’s unscientific.
Me: I see. What is your degree in?
Me: I love geology.
Him: It is pretty cool.
Me: So you know what sedimentary rock is, I assume.
Him: Sedimentology, certainly. Sedimentary rock are rocks formed the by deposition of material in bodies of water.
Me: So water is the mechanism by which sedimentary rock is formed.
Me: So, what percentage off the surface is sedimentary rock?
Him: Well over 75%.
Me: And the other 25%?
Him: Well, the remaining 25% are igneous and metamorphic rocks, but even they are likely ruptures, up-thrust through previous sedimentary layers in later ages.
Me: So, these igneous and metamorphic formations pushed up through or erupted over sedimentary formations?
Him: In some cases, yes.
Me: How much of the world is covered in water?
Him: Over 75% of the world is covered in water.
Me: So, just to make sure I understand your point: on a world that still has 75% of its surface covered in water… and of the 25% that is dry land, 75% of that surface area is covered in sedimentary rock—rock laid down in great bodies of water—you still can’t see any evidence for a world flood? Taken together, on a planetary surface that has 93.75% of its surface directly formed by water, the idea of a world flood is “unscientific”. You choose to affix your skepticism to a mere 6.25% of igneous and metamorphic land formations, which even you admit may have pushed up through sedimentary formations—right? Is that what your PhD in geology taught you—to bank on 6.25%?
He didn’t say anything for the rest of lunch.