Interesting. As far as this specific Gulf graphic, I find myself wondering about all that water, at least halfway up the Mississippi Valley, and the stress it would exert upon the New Madrid fault, too. As bad as the death and destruction from coastal inundation would be, it's slowly dawning upon me that it would just be the beginning.
Yup. Have you considered the 'cosmic winter' that is sure to follow from all the sulfuric acid droplets blocking the sun for years.
"The six year long volcanic winter and 1000-year-long instant Ice Age that followed Mount Toba's eruption may have decimated Modern Man's entire population. Genetic evidence suggests that Human population size fell to about 10,000 adults between 50 and 100 thousand years ago. "
That reflects the shorelines 65 Myears ago.