The question they raise is that there is not enough mud on the sea floor. It is a classic example of how the leadership in Biblical Christianity and Biblical Creationism con the gullible public, of the dishonesty of Biblical Christian Leadership.
First off, they make the assumption that "seas" are those we are familar with today.
That is of course, patently false, demonstrably false, and frankly, the "Creation Scientists" know that and just lie to the public.
We can identify many ancient oceans. For example, the summit of Mount Everest, the lowest exposed layers of the Grand Canyon, all of central North America, the Sahara Desert, the Gobi Desert, and quite frankly, a significant part of all the land we live on are the very sediments that they say are missing.
Subduction is a force that removes evidence. Those areas that do get subducted are then melted and eventually return to the surface as magma.
Biblical Creation Scientists simply lie.
There is no other way to explain it.
The missing mud is everywhere.
Aslan is not a
Tame Lion