'MYSTERY QUEST'- Drs. Greg & Lora Little's Series On History Channel

It's the sea level studies by Michael Faught of FSU as well as Toscano & McIntyre that allow us to deduce that it was one large island during the Pleistocene era. Sub-bottom profiling only tells us what the shape of the seafloor is underneath sedimentary accretion -i.e. -what's under the the sandy bottom.  I think what Greg is talking about is definitive, archeological/artifactual proof, but IMO that's been found via sidescan sonar in 1998 and 2006 at the correct depth which automatically places these structures into the antediluvian timeframe.