Great share, @Paraleptopecten!
Well, the AIG answer to that question is that this ordered nature of the geological column reflects the order (as in sequence) that habitats were subsumed and then buried by the global floodwaters. Personally, I find this confusing… AIG likes to emphasise the dramatic and catastrophic nature of the flood, but at the same time wants to assert that it produced neat geological layers. That strikes me as having one’s cake and eating it.
I’ve also heard the argument that more complex life was able to make it to higher ground and thus were buried last. However, one would expect slower complex lifeforms would be consumed by the flood before faster ones. Thus, I would expect to see sloths buried alongside brachiosaurs and diplodocus on a lower level to cheetahs and velociraptors. How fast is the average antediluvian human when trying to escape a global tsunami?