Index map
Sequences of folded Paleozoic rocks in the southern Appalachians of Alabama and Tennessee match those in the eastern Ouachita Mountains of Arkansas, across the deep Mississippi River Embayment. Because these crustal wrinkles date to the same period of continental-scale collision, the two ranges once were almost certainly continuous. The gap, a 160-million-year-old structural trough, is a legacy from the time when the collided masses of North and South America parted company and opened the Gulf of Mexico. |
