The Appalachian Mountains were primarily formed by the collision of tectonic plates during the Paleozoic Era.

The Appalachian Mountains were shaped by a series of tectonic events, including the collision of the North American, African, and European plates during the Paleozoic Era around 300-480 million years ago. This collision caused the Earth's crust to fold and uplift, forming the ancient mountain range. Over time, erosion has played a secondary role, wearing down the peaks and creating the rounded shapes seen today. The Appalachians are among the oldest mountain ranges in the world, with geological evidence of their origins dating back hundreds of millions of years. These tectonic processes, coupled with ongoing erosion, have given the region its unique topography and geological diversity.