[colorado tanker]

That seems like a good guess. By the time the Mississippi formed, the Ouachitas would have eroded to their modern height, making it fairly easy for the huge amount of water coming available at the end of the ice age to break through.

[blam]

With that same thought in mind, I'm beginning to wonder if the Gulf Of Mexico became fresh water at one time.

I've speculated before, on other threads, that the Gulf Of Mexico may have been blocked (to the world's oceans) from the Yucatan across Cuba and to Florida and had dessicated to low water levels during the Ice Age. This surge of fresh water may have flooded the Gulf Of Mexico and broke the 'dams'.

[Bernard Marx]

I can't speak to the whole issue but the snippet mentions the Missouri earthquakes and diamonds in Arkansas. I know there are plenty of volcanic/contact metamorphic indications in western North Carolina too.

All those indicate substantial tectonic activity: plate movement and some event that allowed plutonic rocks in the form of diatremes (Arkansas) and pegmatite dikes (N.C.) to surge upward from very deep levels. Sounds to me like there was lots of rockin' and rollin' in that area long before Elvis's time.