The layers are as flat as the floor of a series of shallow seas covering the area with intervening periods of erosion, which is what the papers I’ve linked say.
What flat sea floors are being referred to?
We see parallel layers in all the sedimentary strata covering vast areas across the world. So, at all of these places, they must’ve had flat sea floors. Yet, we do not see flat sea floors covering vast areas across the globe now.
https://debatingchristianity.com/forum/viewtopic.php?p=1056804#p1056804