Palinspastic Map of Devonian Strata of Alabama and Northwest Georgia: Geological Notes

Forty-four published structural sections were used to prepare a 1:500,000-scale palinspastic map of the outcrop traces of Devonian strata in Alabama and Georgia, restored to remove the effects of the late Paleozoic Alleghany orogeny. Preparation of the palinspastic map assumed a décollement under the Valley and Ridge province at the level of the Lower Cambrian Rome Formation. Estimated foreshortening of the deformed outcrop belts ranges from 11 mi (18 km) in the northeast to 53 mi (85 km) at the southwest termination of the Appalachians where they plunge beneath the coastal plain. The foreshortening increases from 17 percent in the northeast to 64 percent in the southwest. This is interpreted as evidence that the Appalachian orogenic trend has begun a deflection toward the west before plunging beneath the coastal plain, and also supports the hypothesis that the Appalachian orogenic belt swings farther westward and merges into the Ouachita orogenic trend.