What Caused the Formation of the Appalachian Mountains?

By Staff WriterLast Updated Mar 27, 2020 7:50:37 AM ET

The Appalachian Mountains were formed when colliding tectonic plates folded and upthrusted, mainly during the Permian Period and again in the Cretaceous Period. The folds and thrusts were then eroded and carved by wind, streams and glaciers. These erosive processes are ongoing, and the topography of the Appalachian Mountains continue to change.