 Currently, specific species of corals and mollusks that can be demonstrated to lack any recrystallisation using petrographic and X-ray diffraction techniques are the preferred samples for dating.Any limestone sample that shows the least amount of recrystallisation is now regarded as incapable of yielding a scientifically valid date and not even worth an attempt at dating.Finally, it is well documented that about 15,000 calendar years ago, sea level in this region was between below present sea level.