A complicated sequence of marine ingression and isostatic rebound flooded and emptied the landscape.

The Mississippian was a period of marine ingression in the Northern Hemisphere: the ocean stood so high only the Fennoscandian Shield and the Laurentian Shield stood above sea level.

An interesting aspect, very poorly studied up to now, is that in coincidence with the regression in the northern hemisphere, southern continents experienced a massive marine ingression, the first related to the Atlantic Ocean, that formed at least three vast epeiric seas in South America.