Maybe this will be clearer: It looks from the cross sections like the strata in the Gulf, which are not measured any deeper than the Jurassic level, are the same strata as are found on the continents, whereas in the oceans we don't find those strata, as I understand it. If you think we do then fine, that can be part of the argument. But my understand has been that the strata in the oceans are not the same strata. But since those in the Gulf do seem to be the same strata I supposed that they had formed on the land and that the Gulf itself formed after they were all laid down, which seems to be the case with a lot of phenomena. In that sense it is not part of the oceans, even though now it might be right to call it a sea or part of the oceans. It's just not the same sea that was there during the laying down of the strata.