During early Late Cretaceous the area of the northern Mississippi Embayment was occupied by a structural and topographic dome standing nearly 1000 feet above sea level. Rocks as old as Cambrian were exposed on its crest.
Downwarping of the dome, which commenced in Late Cretaceous time, resulted in the development of the Mississippi Embayment syncline, now filled with sediments of Cretaceous, Paleocene, and Eocene age. The flanks of the Mississippi Embayment syncline slope uniformly about 30 feet per mile. Most of the bending occurred near the synclinal axis, which generally follows the present course of the Mississippi River. Faults cutting the Paleozoic basement and, in some areas, extending upward into the overlying younger rocks resulted from superposition of the narrow synclinal bend across the now-buried structural high. Adjustment also probably occurred by faulting of Paleozoic rocks along the Tennessee River, where the eastern flank of the syncline was bent downward. As a result of structural movements during the Cretaceous and later periods, the old dome has been depressed beneath the Mississippi Embayment and now forms the Pascola arch connecting the Ozark and Nashville domes.