The Appalachian Mountains formed due to tectonic plate collisions during the Paleozoic era.

The Appalachian Mountains were primarily formed through tectonic plate collisions that occurred over hundreds of millions of years, particularly during the Paleozoic era. These collisions involved the convergence of ancient landmasses, which caused the crust to fold, uplift, and create mountain ranges. The process is part of a series of orogenies (mountain-building events), including the Taconic, Acadian, and Alleghanian orogenies, which led to the complex geological structure we see today.