The observed patterns take too long to form to be possible within the time
scale envisioned in any scenario that tries to cram a large portion of the
geologic record into the Flood.
I am most familiar with the issue of isotopic ratios. Samples from around
the world show changes in such ratios as 13C to 12C, 87Sr to 86Sr, 16O to
18O, etc. These changes can be seen in marine and, depending on the
behavior of the element, often in terrestrial or fresh-water deposits. For
such changes to occur, there must be enough time for the global input
patterns to change and for the new ratio to be mixed throughout the oceans.
Also, there must be enough time for sediment to be deposited and isolated
from the new, changed ratio. The consistancy of the ratio shifts with
other lines of evidence such as biostratigraphy, magnetostratigraphy,
Milankovitch cycles, and radiometric dating also supports the accuracy of
the geologic column.
David Campbell